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Nanoparticles (NPs) are tiny – around 1 to 100 billionths of a meter – and can have different chemistries and behaviours than the same material of larger size. This property has led to advances in a wide range of industries, but it can also confer toxicity. Size measurements are the main way NPs are identified but a lack of standardised methods for identifying ones with complex shapes has hindered evaluation of their potential harm.
The progress of the VAMAS interlaboratory comparison Project P13 "Lateral size of graphene oxide flakes by SEM" within the Technical Working Area 41 "Graphene and Related 2D Materials" is presented. The challenges at sample preparation on substrates for accurate measurement and image analysis as well as two different analysis approaches, containing exact guidance how to measure the main descriptors for the lateral size measurement of the imaged graphene oxide flakes with Scanning Electron Microscopy are highlighted. The implementation of the results into the corresponding ISO technical specification AWI/TS 23879 is also discussed and planned, in relation with the AFM part.
Functionalized Ti3C2Tx nanosheets based biosensor for point-of-care detection of SARS-CoV‑2 antigen
(2023)
MXenes are considered a promising class of two-dimensional materials with extraordinary physical and electrochemical properties. Distinguished features like high specific surface area and outstanding electrical conductivity make them suitable for electrochemical biosensing applications. Here, we report the development of a biosensor involving the functionalized MXene−titanium carbide nanosheets (Ti3C2Tx-NS) and monoclonal antibodies against the SARS-CoV-2 nucleocapsid protein (anti-SARS-CoV-2 mAb) to design a point-of-care device for detection of the SARS-CoV-2 nucleocapsid protein (SARS-CoV-2 NP) antigen. Few-layered titanium carbide nanosheets (denoted as FL-Ti3C2Tx-NS) have been synthesized using a single-step etching and delamination method and characterized using optical and electron microscopy techniques revealing the suitability for immunosensing applications. Binding studies revealed the excellent affinity between the biosensor and the SARS-CoV-2 NP. Electrochemical detection of SARS-CoV-2 NP is performed using differential pulse voltammetry and read by a smartphone-based user interface. The proposed FL-Ti3C2Tx-NS based biosensor offers the detection of SARS-CoV-2 NP with a limit of detection of 0.91 nM in a wide detection range in spiked saliva samples. Additionally, there is no cross-reactivity in the presence of potential interferants like SARS-CoV-2 spike glycoprotein and bovine serum albumin. These findings demonstrate the potential of MXenes in developing a rapid and reliable tool for SARS-CoV-2 NP detection. While we report the biosensing of SARS-CoV-2 NP, our system also paves the way for the detection of other SARS-CoV-2 antigens like spike protein or other biomolecules based on antigen−antibody interactions.
Accurate characterisation of the morphology (size) and chemistry of graphene-related 2D materials (GR2M) is key in understanding their extraordinary functionalities. Hence, not only the tailoring of these functionalities aiming at applications of increased-performance becomes possible, but also the correlation of the physico-chemical properties with the understanding of the potential toxicity eventually enables a safe and sustainable development of the GR2M for new applications. Whilst AFM and Raman Spectroscopy are recommended to measure the thickness of GO flakes, Scanning Electron Microscopy (SEM) is the most suited method to assess their lateral size, which varies between tens of µm down to below 100 nm. In this paper, procedures for the accurate determination of lateral size of graphene oxide (GO) flakes by SEM are presented. The prerequisite for accurate flake size analysis is the proper sample preparation, i.e. deposition of ideally isolated flakes on a substrate, with the flakes being unfolded, non-overlapped, parallel with the substrate, and having a high coverage density. Examples of optimum image caption conditions and image analysis procedures will be presented. The size descriptors and their measurement are described in the context of the corresponding analysis approach: i) length and width of the flakes with a quick and rough, but robust procedure, and ii) exact contouring of the flakes as part of a highly accurate, but more time-consuming measurement approach. The possibility of application of automated image analysis is discussed as the alternative to the manual flakes analysis.
The datasets from (Hard Energy) X-ray photoelectron spectroscopy, X-ray diffraction and Scanning Electron Microsopy are related to the publication
G. Chemello, X. Knigge, D. Ciornii, B.P. Reed, A.J. Pollard, C.A. Clifford, T. Howe, N. Vyas, V.-D. Hodoroaba, J. Radnik
"Influence of the morphology on the functionalization of graphene nanoplatelets analyzed by comparative photoelectron spectroscopy with soft and hard X-rays"
Advanced Materials Interfaces (2023), DOI: 10.1002/admi.202300116.
Quantitative Microstructural Analysis - VAMAS TWA 37 & Liaison with ISO/TC 202 Microbeam Analysis
(2023)
The progress in activities on Microbeam Analysis under VAMAS/TWA 37 is reviewed. Particularly the liaison with the new projects within the ISO technical committee TC 202 is presented and discussed with respect to the identification and launching corresponding VAMAS projects. The ongoing project "FIB sample processing for TEM" is presented in detail.
Regional standardisation activities and how VAMAS can help in any way to promote activities are reported.
Activities related to organisational updates, government initiatives/priorities (especially related to Materials), details of any strategy documents publicly available, networks within Germany and how we engage are presented.
In the present paper we show an approach of measuring large numbers of nanoparticles in a single scan TKD. TiO2 anatase nanoparticles (NP) of bipyramidal shape were deposited on standard carbon grid used for TEM. The procedure used promoted formation of NP ‘monolayer’ islands with uniform distribution of NPs on the carbon surface which allowed mapping of large number of nanoparticles in the single island.
Collection of whole map covering ~2800 nanoparticles took nearly 20 minutes. Inverse pole figure color coded map indicates that the NPs are either lying on a {101} facet (within 10° range around perfect {101} parallel to the carbon surface orientation) on the carbon film or are lying on a {100} facet (within 10° range around the perfect {100} parallel to the carbon surface orientation). Very unlikely was the NP orientation standing on a {001} face. The NPs size distribution described as equivalent circle diameter (ECD) has been also evaluated and the mean NP ECD was 59 nm with standard deviation of 15 nm, i.e. in good agreement with electron microscopy or AFM results.
This study shows high potential of the technique for crystalline NPs analysis with respect to geometrical orientation of the particles on the substrate. With known orientation, the 3D dimensional characterisation of such non-spherical NPs becomes possible from 2D projection electron micrographs. Moreover, the NP size distribution can be easily extracted. Superior accuracies down to 1-2 nm are achievable. The approach is applicable also on thin lamellae extracted from particulate (or mesoporous) layers.
Newly developed methodical approaches with an emphasis on correlative imaging analysis of morphology and chemistry of nanomaterials will be presented. Correlative imaging by high-resolution SEM with STEM-in-SEM as well as with EDS, and further with AFM, or with the new technique TKD (Transmission Kikuchi Diffraction) will be explained on various examples of nanostructures, both as starting materials and as embedded/functionalized nanoparticles in products. The unique analytical benefits of the Auger electron probe as a veritable nano-tool for the local surface chemistry will be highlighted. Examples of hybrid analysis of the bulk of nanomaterials by X-ray Spectroscopy and the highest surface-sensitive methods XPS and ToF-SIMS as advanced surface characterization methods available in the Competence Centre nano@BAM will be showed. Particularly for the spatially resolved analysis of the chemistry of nanostructures, such in-depth and lateral gradients of chemistry within mesoporous thin layers, or the completeness of the shells of core-shell nanoparticles, the latter methods are inherent.
Other dedicated developments like approaches for the quantitative determination of the porosity of thin mesoporous layers by electron probe microanalysis (EPMA) with SEM or the quantitative determination of the roughness of particle surface by high-resolution imaging with electron microscopy will be also presented.
An overview on the VAMAS technical working areas (TWA) and projects where Germany is active has been given. The role of VAMAS as an international pre-standardisation platform, including its intense collaboration with international bodies ISO, CEN, OECD and CCQM and national organizations like DIN has been highlighted.
(Pre)Standardisation and Metrology in Microbeam Analysis – Ongoing Activities and Opportunities
(2023)
The presentation addresses the current ongoing projects as well as the gaps and opportunities in microbeam analysis within ISO/TC 202 Microbeam Analysis standardisation body and in-liaison Technical Working Areas (TWAs) at the pre-standardization platform of VAMAS (Versailles Project on Advanced Materials and Standards).
Electron probe microanalysis (EPMA)is a non-destructive technique which assumes a sample of homogenous (bulk) chemical composition and can, therefore, not be used for thin film samples. However, in combination with one of the possible thin film software packages, STRATAGEM, the thickness as well as the composition of such films on a substrate can be determined.
This has been demonstrated for FeNi on Si and SiGe on Al2O3 film systems. For both systems five samples with different elemental composition and a reference were produced and characterised by the Korean research institute KRISS using inductively coupled plasma mass spectrometry (ICP-MS), Rutherford backscattering (RBS), and transmission electron microscopy (TEM).
In 2021, a new and open source thin film evaluation programme called BADGERFILM has been released. It can also be used to determine thin film composition and thickness from intensity ratios of the unknown sample and standards (k-ratios).
In this contribution, we re-evaluated the data acquired for the FeNi and SiGe systems using the BADGERFILM software package and compared the resulting composition and thickness with the results of the established STRATAGEM software and other reference methods. With the current evaluation, the BADGERFILM software shows good agreement with the composition and thickness calculated by STRATAGEM and provided by the KRISS.
These results between two well-known layered material systems analysed with available conventional EMPA approaches (STRATAGEM and direct thickness measurement by TEM) and a new one (BADGERFILM) proves that reliable non-destructive thin film analysis is possible. In this way, we validate the performance of the new software, which is not at all self-explanatory for such
complex quantification algorithms lying behind the final quantified results.
Following points are presented and discussed: i) nPSize as an EMPIR project on the nanoparticle size and shape distribution of (more) complex particles including sample preparation and machine learning approaches; ii) parallel development of ISO 21363 (PSSD by TEM), ISO 19749 (PSSD by SEM), ISO 22292 (3D TEM), ISO 52408 (NP Prep for AFM and EM), iii) VAMAS and pre-standardisation, TWA 34 „Nanoparticle Populations“ with two nPSize ILC projects P15 & P16 – results to be published and integrated in ISO 21363 (PSSD by TEM); iv) Remaining challenges: platelets, 2D materials (TiO2 and GR2M); v) Reference data sets as part of a complete Characterisation Workflow.
Die Bestimmung der Nanopartikelgrößen- und -formverteilung nach OECD TG 125 mit der Transmission and Scanning Electron Microscopy (SEM/TEM) wird punktuell vorgestellt:
- Generelles Messprinzip
- Beispiele
- Korrelative Mikroskopie
- Welchen Durchmesser misst die Methode?
- Welche Partikel kann diese Methode messen?
- Welche Informationen kann diese Methode liefern?
- Wo stößt die Methode an ihre Grenzen?
- Implementierung und Datenauswertung,
- Reporting.
Anschließend wurde eine Q&A-Session für die Imaging-Methoden organisiert.
The progress in the VAMAS Project #15" Measurement of particle size and shape distribution of bipyramidal titania including deposition from liquid suspension" within TWA 34 Nanoparticle Populations is presented with highlight of the following points:
- Determine and compare particle size and shape distribution by means of:
• electron microscopy (SEM, TEM, STEM-in-SEM)
• atomic force microscopy (AFM)
• small angle X-ray scattering (SAXS)
- Determine uncertainty induced by deposition protocol from liquid suspension with comparison to known values from a prior ILC with already deposited nanoparticles on TEM grids.
- Provide comparative validation of protocols for the techniques other than TEM.
The progress of the VAMAS Project 16 "Measurement of (relative) number concentration of bimodal silica nanoparticles including deposition from liquid suspension" in TWA 34 Nanoparticle Populations is presented. Follwowing points are discusssed:
- Validate the performance of imaging methods to measure the relative number concentration
• electron microscopy (SEM, TEM) and atomic force microscopy (AFM)
• two modes of bimodal (30 and 60 nm) silica nanoparticles
- Validate the performance of small angle X-ray scattering (SAXS) for the traceable measurement of the number concentration of the two modes.
Titanium and its alloys are known to allow the straightforward laser-based manufacturing of ordered surface nanostructures, so-called high spatial frequency laser-induced periodic surface structures (HSFL). These structures exhibit sub-100 nm spatial periods – far below the optical diffraction limit. The resulting surface functionalities are usually enabled by both, topographic and chemical alterations of the nanostructured surfaces. For exploring these effects, multi-method characterizations were performed here for HSFL processed on Ti–6Al–4V alloy upon irradiation with near-infrared ps-laser pulses (1030 nm, ≈1 ps pulse duration, 1–400 kHz) under different laser scan processing conditions, i.e., by systematically varying the pulse repetition frequency and the number of laser irradiation passes. The sample characterization involved morphological and topographical investigations by scanning electron microscopy (SEM), atomic force microscopy (AFM), tactile stylus profilometry, as well as near-surface chemical analyses hard X-ray photoelectron spectroscopy (HAXPES) and depth-profiling time-of-flight secondary ion mass spectrometry (ToF-SIMS). This provides a quantification of the laser ablation depth, the geometrical HSFL characteristics and enables new insights into the depth extent and the nature of the non-ablative laser-induced near-surface oxidation accompanying these nanostructures. This allows to answer the questions how the processing of HSFL can be industrially scaled up, and whether the latter is limited by heat-accumulation effects.
The main objective was to assess homogeneity of two bimodal gold materials, namely nPsize1 and nPSize2, containing approximately 1:1 and 10:1 particle number-based ratio of ~30nm and ~60nm particles. Particle number-based concentration within the two size fractions was determined with spICP-MS using the particle frequency method of calibration.
Liaison of ISO/TC 202 Microbeam Analysis with VAMAS/TWA 37 Quantitative Microstructural Analysis
(2023)
The progress in activities on Microbeam Analysis under VAMAS/TWA 37 is reviewed. Particularly the liaison with the new projects within the ISO technical committee TC 202 is presented and discussed with respect to the identification and launching corresponding VAMAS projects. The ongoing project "FIB sample processing for TEM" is presented in detail.
Liaison activities within ISO/TC 202 'Microbeam Analysis' which are relevant to ISO/TC 229 'Nanotechnologies' are reported acoording to the structure defined by ISO/TC229 Nanotechnologies Liaisons Coordination Group (NLCG): new standards/documents, coordination issues, and further detailed specific information, e.g. publications, events, comments.
The basic principles of generation of electrons and X-rays and the operation of SEM/EDS instruments are presented. Examples, recent successes and challenges in the analysis of nano-structures are given. Multi-method analytical approaches with the focus on imaging the nanoscale are highlighted. Details on the sample preparation and persepective on the automated analysis (sample preparation, measurement, data analyis and storage) are given. Metrological aspects, standardisation, and reference materials are also emphasized by examples.
The VAMAS/TWA 45 Project 2 “Development of standardized methodologies for characterisation of microplastics with microscopy and spectroscopy methods” involving 85 participants around the world is primarily discussed with respect to the results received and a first data evaluation. Status of the Project "Guidelines for defining reference materials for plastic degradation in marine environment" is reported and two new project proposals are presented: "Development of standardized methodologies for characterisation of nanoplastics (starting soon, BAM as leader?) and "Development of analytical protocols for the identification and quantification of microplastics of fibrous shape (still in negotiation)".
microscopy (AFM), or X-ray reflectometry. For the additional determination of thin film composition, techniques like X-ray photoelectron spectroscopy (XPS) or mass spectrometry-based techniques can be used. An alternative non-destructive technique is electron probe microanalysis (EPMA). This method assumes a sample of homogenous (bulk) chemical composition, so that it cannot be usually applied to thin film samples. However, in combination with the thin film software StrataGEM, the thickness as well as the composition of such films on a substrate can be determined.
This has been demonstrated for FeNi on Si and SiGe on Al2O3 film systems. For both systems five samples with different elemental composition and a reference were produced and characterised by Korean research institute KRISS using inductively coupled plasma mass spectrometry (ICP-MS), Rutherford backscattering (RBS), and transmission electron microscopy (TEM). These samples were used for an international round robin test.
In 2021, a new and open-source thin film evaluation programme called BadgerFilm has been released. It can also be used to determine thin film composition and thickness from intensity ratios of the unknown sample and standards (k-ratios).
In this contribution, we re-evaluated the data acquired for the FeNi and SiGe systems using the BadgerFilm software package and compared the resulting composition and thickness with the results of the established StrataGEM software and other reference methods. With the current evaluation, the BadgerFilm software shows good agreement with the composition and thickness calculated by StrataGEM and as the reference values provided by the KRISS.
Morpho-Chemical Characterisation of Me-TiO2 Nanoparticles for Enhanced Photocatalytical Activity
(2022)
The conversion of solar energy into electricity and solar fuels is of crucial importance for a green and sustainable future. Water splitting using semiconductor photo-catalysts is considered a sustainable method to produce clean hydrogen (H2) fuel. Nevertheless, H2 photo-production efficiency remains still low, although extensive research works to understand better the mechanisms of the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER) are being carried out. In this respect, TiO2 is a key photoactive material, usually employed with a co-catalyst deposited onto the surface to enhance charge carriers’ separation and catalyze surface charge transfer reactions. The deposition of a co-catalyst on the TiO2 nanoparticle surface represents one successful way to enhance the activity of the photocatalyst through a modification of its surface and redox properties. In this context, high-resolution scanning electron microscopy coupled with elemental analysis by energy-dispersive X-ray spectroscopy (EDS) is fundamental for studying and understanding the effect of the nanoparticle morphology on the functional properties of shape-controlled TiO2 crystals (bipyramides, platelets, and elongated particles). Different types of metal-semiconductor combinations, TiO2 shapes and dopant metals (Ag, Pt, etc) and metal concentrations will be discussed.
In the present talk the basics of the Raman spectroscopy and particularly of Raman microscopy are explained. Advantages and disadvantages of the method are highlighted through selected case studies. In the second part of the lecture examples of correlative imaging with electron, X-ray, ion and optical microscopies from micro- to the nanoscale are highlighted.
Nanoparticle Populations
(2022)
Two new projects P15 Measurement of particle size and shape distribution of bipyramidal titania including deposition from liquid suspension and P16 Measurement of (relative) number concentration of bimodal silica nanoparticles including deposition from liquid suspension have been started at VAMAS/TWA 34 under the lead of BAM. First results are presented and discussed.
Quantitative Microstructural Analysis - VAMAS TWA 37 & Liaison with ISO/TC 202 Microbeam Analysis
(2022)
The progress in activities on Microbeam Analysis under VAMAS/TWA 37 is reviewed. Particularly the liaison with the new projects within the ISO technical committee TC 202 is presented and discussed with respect to the possibility of identifying and launching related VAMAS projects. The recently started project FIB sample processing for TEM is highlighted. Need of more promotion for the engagement of more participants from industry and academia at national, European and international level is highlighted. Also, the competition with the other technical working areas (on 'nano' or materials-related) is critically discussed. Further, a short overview of the VAMAS areas of activities is given where Germany is involved. Planed regional VAMAS Workshops in Germany in 2023 are announced.
Core-shell (CS) particles have been increasingly used for a wide range of applications due to their unique properties by merging individual characteristics of the core and the shell materials. The functionality of the designed particles is strongly influenced by their surface roughness. Quantitative evaluation of the roughness of CS microparticles is, however, a challenging task for Scanning Electron Microscopy (SEM).
The SEM images contain two-dimensional (2D) information providing contour roughness data only from the projection of the particle in the horizontal plane. This study presents a practical procedure to achieve more information by tilting the sample holder, hence allowing images of different areas of a single particle to be recorded at different orientations under the same view angle. From the analysis of these images, quasi three-dimensional (3D) information is obtained.
Three types of home-made particles were investigated: i) bare polystyrene (PS) particles, ii) PS particles decorated with a first magnetic iron oxide (Fe3O4) nanoparticle shell forming CS microbeads, iii) PS/Fe3O4 particles closed with a second silica (SiO2) shell forming core-shell-shell (CSS) microbeads. A series images of a single particle were taken with stepwise tilted sample holder up to 10° by an SEM with high-resolution and surface sensitive SE-InLens® mode.
A reliable analysis tool has been developed by a script in Python to analyze SEM images automatically and to evaluate profile roughness quantitatively, for individual core-shell microparticles. Image analysis consists of segmentation of the images, identifying contour and the centre of the particle, and extracting the root mean squared roughness value (RMS-RQ) of the contour profile from the particle projection within a few seconds.
The variation in roughness from batch-to-batch was determined with the purpose to set the method as a routine quality check procedure. Flow cytometry measurements provided complementary data. Measurement uncertainties associated to various particle orientations were also estimated.
The main outcomes of the EMPIR project nPSize are presented and the suitability of the new capabilities, e.g. reference materials, sample preparation protocols, measurement procedures, and data analysis, to be standardized and implemented in accredited analytical laboratories is discussed. Complementation and/or filling gaps of published and ongoing standardisation projects on size, shape and number concentration measurements under ISO/TC 229/JWG 2 are offered.
The two VAMAS inter-laboratory comparisons resulted from the nSPize project and just started under TWA 34 Nanoparticle Populations (Projects #15 and #16) of bipyramidal TiO2 anatase and bimodal SiO2 nanoparticles are presented in detail.
Both essential aspects of the surface of solid matter, its morphology and chemistry, are studied traditionally at BAM starting in the 60’s with different cyclical research focus areas, mostly related either to applicative research or method development. In the recent years, the focus has shifted almost exclusively to the nano-analytics of advanced materials such as complex nanoparticles, (ultra)thin films/coatings, nanocomposites, 2D materials, energy materials, etc. This is also the reason why BAM has established recently the new Competence Center nano@BAM (www.bam.de/Navigation/DE/Themen/Material/Nanotechnologie/sichere-nanomaterialien.html) with the five sub-fields nanoCharacterisation, nanoMaterial, nanoSafety, nanoData and nanoTechnology. The link to the BAM central guidelines to the safety in technology and chemistry is given by the development of reference products such as reference measurement procedures, reference (nano)materials, and newly reference data sets. Thus, an internationally well-networked group in surface analysis has been established @BAM, with regular contributions to integral analytical characterization with metrological and standardization background.
Examples of newly developed methodical approaches will be given with an emphasis on correlative nano-analysis of morphology and chemistry of nanomaterials. Correlative imaging by STEM-in-SEM with high-resolution SEM and EDX, and further with AFM or the new technique TKD (Transmission Kikuchi Diffraction) will be explained on various examples of nanostructures, both as starting materials and embedded/functionalized nanoparticles in products. The unique analytical benefits of the Auger electron probe as a veritable nano-tool for surface chemistry will be highlighted. The panoply of advanced surface characterization methods @BAM is completed by discussing examples of hybrid analysis of the bulk of nanomaterials by X-ray Spectroscopy with the highest surface-sensitive methods X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). Particularly for the analysis of the surface chemistry of nanostructures, such as the completeness of the shells of core-shell nanoparticles or in-depth and lateral gradients of chemistry within mesoporous thin layers, the latter methods are inherent.
Other special developments like approaches for the quantitative determination of the roughness of particle surface by electron microscopy or for the quantitative determination of the porosity of thin mesoporous layers by electron probe microanalysis (EPMA) with SEM will be presented.
Experience gained at BAM within the European project ISGScope on the accurate measureemnt of graphene oxide flakes by electron microscopy is presented. Particularly, factors such as the type of solvent, substrate temperature, but also proper, gentle measurement parameters and image analysis conditions towards automation are highlighted. The measurement procedures in develeopment are being prepared to launch an inter-laboratory comparison under VAMAS (TWA41) as preparatory guidance for future standardisation at ISO.
The progress in the activities on Microbeam Analysis under VAMAS/TWA 37 is reviewed. Particularly the liaison with the new projects within the ISO technical committee TC 202 is presented and discussed with respect to the possibility of identifying and launching related VAMAS projects/inter-laboratory comparisons. The recently started project FIB sample processing for TEM is presented. Next projects in the pipeline involving EBSD and TKD are shortly announced. The need of more promotion for the engagement of more experts from industry and academia at national, European and international level is highlighted. Also, the competition with the other technical working areas (on 'nano' or materials-related) is critically discussed.
he main objective of the nPSize project is to improve the measurement capabilities for nanoparticle size based on both measurement methods traceable to SI units and new reference materials. Two basic approaches have been used in order to develop measurement procedures resulting in traceable results of the nanoparticle size distribution: physical modelling for the methods used in the project (TSEM, SEM, AFM and SAXS) and machine learning.
Physical modelling: In this part, the physical models associated with different shape measurements for the techniques TSEM, SEM, AFM and SAXS have been collected and further developed with the aim to simulate the resulting signal as measured by the individual methods. Uncertainties and traceability associated with each model were investigated and evaluated. In the following, the progress on these physical models is reported for each individual method.
Machine Learning modelling: The aim of this part is to use machine learning to enable automatic measurement of nanoparticle shape from expert a-priori information only. No physical model will be used as a-priori information in this task.
The accuracy and traceability of the size results obtained by each technique will be analyzed and compared with the physical modelling. A machine learning database will then be used to create automatic detection algorithms.
The Competence Centre nano@BAM is presenting a new X-ray Photoelectron Spectrometer – the HAXPES (XPS at hard energy) – for researching advanced materials at the nanoscale. With HAXPES detailed chemical information can now be gained not only from the first outermost nanometres of the sample surface, but also from deeper regions.
Top international experts will share their knowledge and key findings on how to utilise HAXPES for exploring the surface of various advanced materials. Following the lectures, we will show you a short demo of the new instrument and answer your questions.
Water splitting using semiconductor photo-catalysts is considered a sustainable method to produce clean hydrogen fuel. Nevertheless, H2 photo-production efficiency remains still low, although extensive research works to understand better the mechanisms of the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER) are being carried out. In this respect, TiO2 is a key photoactive material, usually employed with a co-catalyst deposited onto the surface to enhance charge carriers’ separation and catalyze surface charge transfer reactions. The deposition of a co-catalyst on the TiO2 nanoparticle surface represents one successful way to enhance the activity of the photocatalyst through a modification of its surface and redox properties. In this context, high-resolution scanning electron microscopy (SEM) coupled with elemental analysis by energy-dispersive X-ray spectroscopy (EDS) is fundamental for studying and understanding the effect of the nanoparticle morphology on the functional properties of shape-controlled TiO2 crystals (bipyramides, platelets, and elongated particles). Different types of metal-semiconductor combinations, TiO2 shapes and dopant metals (Ag, Pt, Au, Rh, Pd) and metal concentrations are discussed.
In order to bridge the gap between lab-scale and industrial-scale production of graphene it is necessary to develop processes, equipment and measurement procedures to control the material features. One of the crucial reasons of graphene’s limited commercialization is the lack of standard procedures to properly characterize and define the material chemical and structural properties down to the nanometer level. This leads to many issues regarding material synthesis repeatability, inappropriateness choice of measurands and measurement reproducibility which heavily affect the consistency of the material performance.
In our study, a comparative analysis is performed on two different series (G5 and G6) of industrial graphene powders, each series produced with four types of functionalization: raw graphene, oxygen-functionalized, nitrogen-functionalized and fluorine-functionalized. All the 8 sample variants were analyzed from a chemical and morphological point of view in the form of powders prepared as slightly pressed in metallic sample holders.
The results of the comparative chemical analyses XPS and EDS show a good agreement in the concentration values for all the elements present in the samples, despite the different analysis volumes addressed by the two techniques. For this reason, the samples can be considered homogeneous in both lateral and vertical direction.
A clear influence of the morphology on the composition is evident. Therefore, such correlative measurements of morphology and composition are necessary for a comprehensive characterization of industrial graphene flakes.
One aim of the EMPIR nPSize project 17NRM04 was to develop and validate three classes of candidate reference (test) materials (RTMs), with i) well-defined non-spherical shape, ii) relatively high polydispersity index, and iii) accurate particle concentrations.
To fulfil the requirements of the project, 11 different types of materials were prepared. Following the initial assessment of the materials suitability, nPSize5_PT_UNITO, nPSize6_AC_UNITO and nPSize7_GN_CEA materials were found unsuitable for the project, due to various reasons. PT material was deemed unsuitable due to its predominantly agglomerated nature. AC material contained relatively high amount of impurities (other particle forms). GN material was found too heterogeneous in both the length and width for the purpose of the project. The remaining 8 candidate RTMs were assessed for their homogeneity and stability and used for successful delivery of the associated activities within the nPSize project.
Electron Probe Microanalysis (EPMA) provides a non-destructive approach in the dedicated thin film analysis mode with the commercial StrataGem software. Recently, the open-source programme BadgerFilm by Moy and Fournelle became available. Similarly to StrataGem, it is based on the algorithm of Pouchou and Pichoir and needs intensity ratios of the unknown sample and standards (k-values). We have evaluated the k-values measured for the FeNi and SiGe film systems using the BadgerFilm software package and compared the thickness and composition with the results obtained with the established StrataGem software and other reference methods. The thicknesses of the SiGe films obtained by the BadgerFilm software agree within 20% with the StrataGem and TEM results; the elemental compositions BadgerFilm-StrataGEM agree within 2% with one exception (9%).
Nanosafety is becoming increasingly important as nanomaterials are widely used in industrial processes and consumer products. For nanotoxicity measurements prior sterilization of the samples is necessary, but as structure activity relationships are made with properties of pristine particles, the question arises, if the sterilization process has an impact on the physico-chemical properties of nanoparticles and thus on the biological behavior.
This question will be addressed in this talk. For this purpose, results from SEM and EDS measurements are combined with those of a novel lab-based HAXPES spectrometer in order to obtain a more complete picture. At the end, an influence of sterilization will be evident, which indicates a restructuring of the nanoparticles owing to sterilization.
CS particles show unique properties by merging individual characteristics of the core and the shell materials. An alteration particularly in their surface roughness affects the final performance of the particles in the targeted application. Quantitative evaluation of the roughness of CS microparticles is, however, a challenging task employing microscopic techniques being scarce and showing large differences in terms of methodology and results.
In our previous work, we have reported a systematic study with a reliable analysis tool, which evaluates profile roughness quantitatively, for individual core-shell microparticles using electron microscopy (EM) images of both types, Scanning Electron Microscopy (SEM) and transmission mode SEM (or TSEM). The SEM images contain two-dimensional (2D) information, therefore, provide profile roughness data only from the projection in the horizontal plane (in other words, from the “belly”) of a spherical particle. The present study offers a practical procedure to give access to more information by tilting the sample holder and hence allowing images of a single particle to be recorded at different orientations under the same view angle. From the analysis of these images, extended information on surface roughness of the particle can be extracted. Thus, instead of obtaining 2D information from a single SEM image, three-dimensional (3D) information is obtained from 2D projections recorded at different particle orientations.
For test laboratories operating under accreditation schemes like ISO/IEC 17025 (ISO/IEC 17025), as the international reference for testing and calibration laboratories wanting to demonstrate their capacity to deliver reliable results, a periodical control of the critical instrumental parameters of an Energy-Dispersive X-ray Spectrometer (EDS) is required.
This periodical check of an EDS is specified with exact procedures and materials in the ISO 15632:2021 ”Microbeam Analysis – Selected instrumental performance parameters for the specification and checking of energy-dispersive X-ray spectrometers for use in electron probe microanalysis” (ISO 15632). The EDS check can be simplified to the acquisition of only one 10 kV spectrum from a dedicated test material, EDS-TM002, which is made available by BAM since 2009 (https://webshop.bam.de/webshop_en/). The optional BAM software “EDX spectrometer check” is destined to automatically evaluate this spectrum and determine the performance of the EDS in terms of energy resolution and calibration, as well as possible alteration of low-energy efficiency due to detector contamination. Nearly 200 laboratories have the EDS-TM and associated software package in use.
Practical examples based on various types of artifacts occurred in the EDS spectra and a long-term (>10 years) meticulous observation of the own spectrometers will be discussed. Different types of EDS spectrometers are considered, e.g. Si(Li) and SDD, of various window types (AP, the recent one Si3N4 or even windowless), and with different front contact layers (Au and Ni) (Hodoroaba and Procop, 2014). Evaluation of other parameters or effects such as the deadtime at different count rates or pileup effects is also explained with examples.
The thickness of thin films can be measured by various methods, e.g., profilometry, ellipsometry, atomic force microscopy (AFM), or X-ray reflectometry. For the additional determination of thin film composition, techniques like X-ray photoelectron spectroscopy (XPS) or mass spectrometry-based techniques can be used. An alternative non-destructive technique is electron probe microanalysis (EPMA). This method assumes a sample of homogenous (bulk) chemical composition, so that it cannot be usually applied to thin film samples. However, in combination with the thin film software StrataGEM, the thickness as well as the composition of such films on a substrate can be determined.
This has been demonstrated for FeNi on Si and SiGe on Al2O3 film systems. For both systems five samples with different elemental composition and a reference were produced and characterised by Korean research institute KRISS using inductively coupled plasma mass spectrometry (ICP-MS), Rutherford backscattering (RBS), and transmission electron microscopy (TEM). These samples were used for an international round robin test.
In 2021, a new and open-source thin film evaluation programme called BadgerFilm has been released. It can also be used to determine thin film composition and thickness from intensity ratios of the unknown sample and standards (k-ratios).
In this contribution, we re-evaluated the data acquired for the FeNi and SiGe systems using the BadgerFilm software package and compared the resulting composition and thickness with the results of the established StrataGEM software and other reference methods. With the current evaluation, the BadgerFilm software shows good agreement with the composition and thickness calculated by StrataGEM and as the reference values provided by the KRISS.
The conversion of solar energy into electricity and solar fuels is of crucial importance for a green and sustainable future. Water splitting using semiconductor photo-catalysts is considered a sustainable method to produce clean hydrogen (H2) fuel. Nevertheless, H2 photo-production efficiency remains still low, although extensive research works to understand better the mechanisms of the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER) are being carried out. In this respect, TiO2 is a key photoactive material, usually employed with a co-catalyst deposited onto the surface to enhance charge carriers’ separation and catalyze surface charge transfer reactions. The deposition of a co-catalyst on the TiO2 nanoparticle surface represents one successful way to enhance the activity of the photocatalyst through a modification of its surface and redox properties. In this context, high-resolution scanning electron microscopy coupled with elemental analysis by energy-dispersive X-ray spectroscopy (EDS) is fundamental for studying and understanding the effect of the nanoparticle morphology on the functional properties of shape-controlled TiO2 crystals (bipyramides, platelets, and elongated particles). Different types of metal-semiconductor combinations, TiO2 shapes and dopant metals (Ag, Pt, etc) and metal concentrations will be discussed.
The liaison report from the ISO Technical Committee ISO/TC 202 'Microbeam Analysis' for the November 2022 ISO/TC 229 Nanotechnologies Plenary Meeting Nanotechnologies Liaison Coordination Group (NLCG) is provided. Essential Information such as newly published standards and projects in develeopment relevant for ISO/TC 229 resulted from the progress within the last year and additional comments on behalf of ISO/TC 202 are included in the report.
BAM is currently building up a platform of novel nanoRMs relying on iron oxide nanoparticles of different shape, size and surface chemistry. Iron oxide was chosen as a core material because of its relevance to the material and life sciences.
As a first candidate of this series, we present cubic iron oxide nanoparticles with a nominal edge length of 8 nm. These particles were synthesized by thermal decomposition of iron oleate in high boiling organic solvents adapting well-known literature procedures. After dilution to a concentration suitable for electron microscopy (TEM and SEM) as well as for small-angle X-ray scattering (SAXS) measurements, the candidate nanoRM was bottled and assessed for homogeneity and stability by both methods following the guidelines of ISO 17034 and ISO Guide 35.
The particle sizes obtained by both STEM-in-SEM and TEM are in excellent agreement with a minimum Feret of 8.3 nm ± 0.7 nm. The aspect ratio (AR) of the iron oxide cubes were extracted from the images as the ratio of minimum Feret to Feret resulting in an AR of 1.18 for TEM to 1.25 for SEM. Alternatively, a rectangular bounding box was fitted originating from the minimum Feret and the longest distance through the particle in perpendicular direction. This led to AR values of 1.05 for TEM and 1.12 for SEM, respectively. The results confirm the almost ideal cubic shape.
International standardisation network VAMAS is calling for participants in two studies on the measurement of (relative) number concentration of bimodal silica nanoparticles including deposition from liquid suspension and the measurement of particle size and shape distribution of bipyramidal titania including deposition from liquid suspension.
Both essential aspects of the surface of solid matter, its morphology and chemistry, are studied traditionally at BAM starting in the 60’s with different cyclical research focus areas, mostly related either to applicative research or method development. In the recent years, the focus has shifted almost exclusively to the nano-analytics of advanced materials such as complex nanoparticles, (ultra)thin films/coatings, nanocomposites, 2D materials, energy materials, etc. This is also the reason why BAM has established recently the new Competence Center nano@BAM (www.bam.de/Navigation/DE/Themen/Material/Nanotechnologie/sichere-nanomaterialien.html) with the five sub-fields nanoCharacterisation, nanoMaterial, nanoSafety, nanoData and nanoTechnology. The link to the BAM central guidelines to the safety in technology and chemistry is given by the development of reference products such as reference measurement procedures, reference (nano)materials, and newly reference data sets. Thus, an internationally well-networked group in surface analysis has been established @BAM, with regular contributions to integral analytical characterization with metrological and standardization background.
Examples of newly developed methodical approaches will be given with an emphasis on correlative nano-analysis of morphology and chemistry of nanomaterials. Correlative imaging by STEM-in-SEM with high-resolution SEM and EDX, and further with AFM or the new technique TKD (Transmission Kikuchi Diffraction) will be explained on various examples of nanostructures, both as starting materials and embedded/functionalized nanoparticles in products. The unique analytical benefits of the Auger electron probe as a veritable nano-tool for surface chemistry will be highlighted. The panoply of advanced surface characterization methods @BAM is completed by discussing examples of hybrid analysis of the bulk of nanomaterials by X-ray Spectroscopy with the highest surface-sensitive methods X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). Particularly for the analysis of the surface chemistry of nanostructures, such as the completeness of the shells of core-shell nanoparticles or in-depth and lateral gradients of chemistry within mesoporous thin layers, the latter methods are inherent.
Other special developments like approaches for the quantitative determination of the roughness of particle surface by electron microscopy or for the quantitative determination of the porosity of thin mesoporous layers by electron probe microanalysis (EPMA) with SEM will be presented in conjunction with the corresponding advanced materials studied.
Current research projects, promising ideas, including ongoing (pre-)standardization activities in the field of the challenging nano/surface analysis will be touched systematically, with the open goal of identifying future bilateral cooperation possibilities between EMPA and BAM.
In order to assess new nanomaterials and nanoparticles for potential risks to health and the environment, they need to be well-characterised. The measurement of constituent nanoparticle size, shape, and size distribution are important factors for the risk evaluation process.
EMPIR project Improved traceability chain of nanoparticle size measurements (17NRM04, nPSize) is working to assess a range of traceable nanoparticle measurement approaches, including Electron Microscopy (SEM, TEM, STEM-in-SEM), Atomic Force Microscopy and Small Angle X-ray Scattering, and deliver improved calibration methods to users. For the techniques under investigation, physical models of their response to a range of nanoparticle types are developed. Validated reference materials are also used for inter-comparisons of measurement systems, with an evaluation of the associated measurement uncertainty. With project contributions to standards development work, manufacturers will be better placed to assess the human and environmental risks posed by nanomaterials across a whole range of products.
The presentation is structured in the following three parts:
i) Report of the Working Group 4 X-Ray Spectroscopy including the publication of ISO 15632:2021 Microbeam analysis — Selected instrumental performance parameters for the specification and checking of energy-dispersive X-ray spectrometers for use in electron probe microanalysis,
ii) Liaison activities between ISO/TC202 Microbeam Anaylsis and VAMAS/TWA34 Quantitative Microstructural Analysis, and
iii) Liaison activities from ISO/TC202 Microbeam Analysis for ISO/TC229 Nanotechnologies.
Most relevant projects are highlighted for information and further discussions. New initiatives and better promotion of strategic projects are addressed.
A case study on the TEM analysis of the size and shape distribution of TiO2 bipyramidal nanoparticles prepared on TEM grids was included in the recently published ISO standard ISO 21363. It was agreed to organize at a later stage a second inter-lab comparison with the nanoparticles distributed to the participants as a liquid suspension. Protocols for uniform nanoparticle deposition on suited supports developed and optimized within the EMPIR nPSize project are also prepared to be distributed. For this, we have chosen the VAMAS platform (www.vamas.org) which offers an excellent international infrastructure of laboratories with high competence in nanoparticle measurement. The VAMAS technical working area dedicated to nanoparticle measurement is TWA 34 ‘Nanoparticle populations’. For this type of nanoparticles, the size and shape distributions are the primary parameters to be reported. Due to the good deposition protocols developed, an automated image analysis is enabled (in contrast to the manual analysis of irregular TiO2 nanoparticles.
In parallel with the TiO2 nanoparticle exercise, two spherical SiO2 nanoparticle samples with bi-modal size distributions (nominal relative number concentrations of 1:1 and 10:1) are prepared for a second VAMAS inter-lab comparison. Here, the nanoparticle concentration is the primary parameter to be measured. For the imaging methods it is targeted to measure the relative nanoparticle concentrations of the two modes. For the absolute nanoparticle concentration to be measured by imaging methods it is necessary to control the volume of the liquid suspension deposited on the substrate and to obtain such a homogeneous nanoparticle deposition on the substrate which allows to count (or extrapolate) all the deposited particles.
A particle roughness analysis tool, based on electron microscopy images (SEM and TEM). The influence of various parameters on the calculated roughness was also investigated: the setting of the proper threshold, accelerating voltage, etc. The samples were gradually tilted to extend imaging information of more than only one projection. Furthermore, the measurement uncertainty of the profile roughness of particles associated to various orientations was estimated.
A case study on the TEM analysis of the size and shape distribution of TiO2 bipyramidal nanoparticles prepared on TEM grids was included in the recently published ISO standard ISO 21363. It was agreed to organize at a later stage a second inter-lab comparison with the nanoparticles distributed to the participants as a liquid suspension. Protocols for uniform nanoparticle deposition on suited supports developed and optimized within the EMPIR nPSize project are also prepared to be distributed. For this, we have chosen the VAMAS platform (www.vamas.org) which offers an excellent international infrastructure of laboratories with high competence in nanoparticle measurement. The VAMAS technical working area dedicated to nanoparticle measurement is TWA 34 ‘Nanoparticle populations’. For this type of nanoparticles, the size and shape distributions are the primary parameters to be reported. Due to the good deposition protocols developed, an automated image analysis is enabled (in contrast to the manual analysis of irregular TiO2 nanoparticles.
In parallel with the TiO2 nanoparticle exercise, two spherical SiO2 nanoparticle samples with bi-modal size distributions (nominal relative number concentrations of 1:1 and 10:1) are prepared for a second VAMAS inter-lab comparison. Here, the nanoparticle concentration is the primary parameter to be measured. For the imaging methods it is targeted to measure the relative nanoparticle concentrations of the two modes. For the absolute nanoparticle concentration to be measured by imaging methods it is necessary to control the volume of the liquid suspension deposited on the substrate and to obtain such a homogeneous nanoparticle deposition on the substrate which allows to count (or extrapolate) all the deposited particles.
This dataset accompanies the following publication, first published in Scientific Reports (www.nature.com/articles/s41598-021-84287-6):
B. Ruehle, J. Krumrey, V.-D. Hodoroaba, Scientific Reports, Workflow towards Automated Segmentation of Agglomerated, Non-Spherical Particles from Electron Microscopy Images using Artificial Neural Networks, DOI: 10.1038/s41598-021-84287-6
It contains electron microscopy micrographs of TiO2 particles, the corresponding segmentation masks, and their classifications into different categories depending on their visibility/occlusion. Please refer to the publication and its supporting information for more details on the acquisition and contents of the dataset, as well as the GitHub repository at https://github.com/BAMresearch/automatic-sem-image-segmentation
The publicly available document encapsulates the first version of the Catalogue of Services of the future EC4Safenano Centre (CoS 2019).
The CoS 2019 is structured in 12 Service Categories and 27 Service Topics, for each of the 12 categories considered. This architecture configures a 12 x 27 matrix that allows ordering the potential EC4Safenano offer in 324 types of services/groups of services.
Each type of service/group of services is described, in a simple and friendly way, by means of a specific service sheet: the EC4Safenano - Service Data Sheet (EC4-SDS). These EC4-SDSs allow structuring and summarizing the information of each service, providing the customer with a concise view of characteristics of the service and also the contact details with the service provider.
The CoS 2019 deploys a map of services consisting of a set of 100 EC4-SDSs, covering 7 of the 12 Service Categories and 17 of the 27 Service Topics.
The harmonization of services is visualized as a future necessary step in EC4Safenano, in order to strengthen the offer and provide added value to customers with a growing offer of harmonized services in future versions of the CoS.
The information contained in this document is structured in 3 main sections, as follows:
• Catalogue structure. This section describes in short the main characteristics of the CoS 2019.
• Catalogue content. This section represents the core part of the document and encapsulates the set of 100 SDSs displaying the offer proposed by the CoS 2019.
• Online Catalogue. This section describes the resources implemented by EC4Safenano to facilitate the on-line consultation of the CoS 2019 by customers and other interested parties.
The progress in activities on Microbeam Analysis under VAMAS/TWA 37 is reviewed. Particularly the liaison with the new projects within the ISO technical committee TC 202 is presented and discussed with respect to the possibility of identifying and launching related VAMAS projects. Need of more promotion for the engagement of more participants from industry and academia at national, European and international level is highlighted. Also, the competition with the other technical working areas (on 'nano' or materials-related) is critically discussed. Further, a short overview of the VAMAS areas of activities is given where Germany is involved.
As part of the development of a library of accurate and efficient methods for measurement of nanoparticle properties, we develop and optimize a method for the efficient analysis of nanoparticle size distribution from suspensions via microprinting and digital analysis of electron microscopy (SEM and TEM) images, with the ultimate aim of automated quantitative concentration analysis (calculated from drop volume). A series of different nanoparticle suspensions (gold, latex, and SiO2 in varying sizes and concentrations) were printed onto TEM grids in a 4 x 4 array in the concentration range 7x10^8 to 1x10^11 nanoparticles/mL and imaged with SEM. Concentrations and printing conditions (temperature, relative humidity) were varied in order to minimize the coffee-ring effect.
By far most of the current nanoparticle (NP) research is dealing with (quasi-) spherical and/or monodisperse particles. However, many NPs used in industrial applications are rather aspherical and polydisperse. This inhomogeneity considerably hampers their characterization and, particularly, the accurate determination of the nanoparticle size. In order to overcome this problem and to promote the availability of standardized size measurement methods, it is crucial to develop and establish (candidate) reference materials with inhomogeneous size (distribution), aspherical shape as well as agglomerated or aggregated particles.
Therefore, a new set of NPs including Au-, SiO2 , and TiO2-particles is investigated. The range of properties comprises polydisperse spherical, bimodal spherical, rod-like, acicular, bipyramidal, sheet-like as well as cubic NPs. With respect to a good traceability of the measurements, size and size distributions of the candidate reference materials are determined using microscopic methods like scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning electron microscopy in transmission mode (STEM-in-SEM), atomic force microscopy (AFM) as well as small angle X-ray scattering (SAXS) as an ensemble technique. The development of protocols for sample preparation is of particular importance to obtain a homogeneous dispersion of the NPs on a substrate. Further, approaches for signal modelling for all the methods above are being developed. The initiation of two VAMAS (www.vamas.org/twa34/index.html) inter-laboratory comparisons on bipyramidal titania and bimodal silica with different modal concentration ratios will be also highlighted.
It sounds like being a simple analytical task, it is definitely not. The way toward accurate measurement of the size distribution of nanoparticles (NPs) with complex shape, having a broad size polydispersity, with inhomogeneous chemistry, and with a high degree of agglomeration/aggregation is very challenging for all available analytical methods. Particularly for the NPs with complex shape, the access to the smallest dimension (as e.g. required for regulatory purposes) can be enabled only by using imaging techniques with spatial resolution at the nanoscale. Moreover, the full 3D-chacterisation of the NP shape can be provided either by advanced characterization techniques like 3D-TEM tomography or by correlative analysis, i. e. synergetic/complementary measurement of the same field-of-view of the sample with different probes. Examples of the latter type of analysis are: i) electron microscopy for the lateral dimensions and AFM for the height of the NPs, ii) SEM with STEM-in-SEM (also called T-SEM), iii) Electron Microscopy with TKD (Transmission Kikuchi Diffraction) for determination of the geometrical orientation of crystalline NPs, iv) Raman and SEM for e.g. thickness of graphen flakes, or v) Electron Microscopy for descriptive NP shape and SAXS for the NP concentration, the latter as a NP property able to be measured with higher and higher accuracy. For all these types of measurement, reference NPs are necessary for the validation of the measured size. Particularly non-spherical reference NPs are still missing. Examples of such new reference NPs as characterized by the correlative analyses enumerated above will be presented in detail in the contribution.
Nanomaterials and nanoparticles are finding applications across a wide range of technology sectors, from medicine and food to transportation and construction. In order to assess these new materials for potential risks to health and the environment, they need to be well-characterised. The measurement of constituent nanoparticle size, shape, and size distribution are important factors for the risk evaluation process.
EMPIR project Improved traceability chain of nanoparticle size measurements (17NRM04, nPSize) is working to assess a range of traceable nanoparticle measurement approaches, including Scanning Electron Microscopy (also in Transmission Mode), Atomic Force Microscopy and Small Angle X-ray Scattering, and deliver improved calibration methods to users. For the techniques under investigation, physical models of their response to a range of nanoparticle types are developed. Validated reference materials will also be used for an inter-comparison of measurement systems, with an evaluation of the associated measurement uncertainty. With project contributions to standards development work, manufacturers will be better placed to assess the human and environmental risks posed by nanomaterials across a whole range of products.
The main outcomes of the EMPIR project nPSize are presented and the suitability of the new capabilities (e.g. reference materials, measurement procedures, inter-laboratory comparisons) as pertinent contributions to normative projects within CEN/TC 352 Nanotechnologies are discussed. E.g. the first technical report of nPSize on full algorithm sequences for nanoparticle detection and size measurement as developed on both a physical basis (SEM, TSEM, AFM and SAXS) and by machine learning is put at disposal.
We present a workflow for obtaining fully trained artificial neural networks that can perform automatic particle segmentations of agglomerated, non-spherical nanoparticles from electron microscopy images “from scratch”, without the need for large training data sets of manually annotated images. This is achieved by using unsupervised learning for most of the training dataset generation, making heavy use of generative adversarial networks and especially unpaired image-to-image translation via cycle-consistent adversarial networks. The whole process only requires about 15 minutes of hands-on time by a user and can typically be finished within less than 12 hours when training on a single graphics card (GPU). After training, SEM image analysis can be carried out by the artificial neural network within seconds, and the segmented images can be used for automatically extracting and calculating various other particle size and shape descriptors.
Results from different methods applied to micro- and nanoplastics (MNPs) analysis show that there are large gaps in harmonisation with respect to terminology, size classes, sample preparation protocols and, finally, to the comparability of the measurands and descriptors.
Within the European research cluster to understand the health impacts of micro- and nanoplastics (CUSP) working group WG3-Inter-Laboratory Comparisons an overview of the existing detection methods revealing advantages and disadvantages regarding the analytical tasks is being compiled. There is a clear need to develop high class characterized reference materials for MNPs in the size ranges of 100-10 µm and smaller than 10 µm, so that these can be used to validate methods and to make results comparable. Inter-laboratory comparisons (ILCs) on model samples with complex matrices regarding mass, or water samples for number-based methods, will help us to advance the process of harmonization as well as to train users early in process of developing new methods.
We plan to keep all five CUSP projects well-connected also with the 'outside' MNP projects and ILCs and to extract the optimum of needs, capabilities, and efforts in order to launch new VAMAS ILCs which should expand already available ones.
In this breakout session first, an introduction is given on the planning and organisation of an inter-laboratory comparison (ILC) under the pre-standardisation plattform VAMAS within the newly formed technical working area TWA 45 Micro and Nano Plastics in the Environment. An update with the ILCs on micro- and nanoplastic performed so far is also given. In the third part, the requirements for a reference materials are presented. The needs from the different H2020 micro- and nanoplastic projects are collected and compiled in an ILC matrix for joint activities as the next steps.
Gold nanocubes with a monodispersed size distribution (edge = 55 nm) deposited on a silicon wafer. These tiny uniform cubes were produced as reference nanoparticles in the frame of the European project nPSize - Improved traceability chain of nanoparticle size measurements. SEM Image acquired at 10 kV with an in-lens secondary electron detector. Image colored in ImageJ using LUT “Orange hot.” Published in Microscopy and Microanalysis 25(S2) (2019) 2328.
Gold nanocubes with a monodispersed size distribution (edge = 55 nm) deposited on a silicon wafer. These tiny uniform cubes were produced as reference nanoparticles within the EMPIR project nPSize - Improved traceability chain of nanoparticle size measurements. SEM image acquired at 10 kV with an in-lens secondary electron detector. Image colored in ImageJ using LUT “Orange hot.” Published in Microscopy and Microanalysis 25(S2) (2019) 2328.
The progress in activities on Microbeam Analysis under VAMAS/TWA 37 is reviewed. Particularly the liaison with the new projects within the ISO technical committee TC 202 is presented and discussed with respect to the possibility of identifying and launching related VAMAS projects. Need of more promotion for the engagement of more participants from industry and academia at national, European and international level is highlighted. Also, the competition with the other technical working areas (on 'nano' or materials-related) is critically discussed.
The present study addresses the capability of measurement of relative particle number concentration by scanning electron microscopy for model bimodal silica and gold samples prepared in the frame of the European research project “nPSize - Improved traceability chain of nanoparticle size measurements” as candidate reference nanoparticles.
In this paper one refined approach is applied to determine the exact orientation of bipyramidal TiO2 nanoparticles prepared with good dispersion as almost isolated particles on a carbon TEM grid. The advantages of the recently developed high-throughput Transmission Kikuchi Diffraction (TKD) are used to identify quickly and reliably the geometrical orientation of the crystalline TiO2 nanoparticle bipyramids (anatase) on a statistically relevant number of particles.
In this contribution different ways are explored with the aim to generate suitable training data for ‘non-ideal’ samples using various approaches, e.g., computer-generated images or unsupervised learning algorithms such as generative adversarial networks (GANs). We used these data to train simple CNNs to produce segmentation masks of SEM images and tested the trained networks on real SEM images of complex nanoparticle samples. The novel use of CNN for the automated analysis of the size of nanoparticles of complex shape and with a high degree of agglomeration has proved to be a promising tool for the evaluation of particle size distribution on a large number of constituent particles. Further development and validation of the preliminary model, respectively larger training and validation data sets are necessary.
This document is a collection of three JRC Technical Reports that together form the “NanoDefine Methods Manual”, which has been developed within the NanoDefine project ‘Development of an integrated approach based on validated and standardized methods to support the implementation of the EC recommendation for a definition of nanomaterial’, funded by the European Union’s 7th Framework Programme, under grant agreement 604347. The overall goal of the NanoDefine project was to support the implementation of the European Commission Recommendation on the definition of nanomaterial (2011/696/EU). The project has developed an integrated empirical approach, which allows identifying a material as a nano- or not a nanomaterial according to the EC Recommendation. The NanoDefine Methods Manual consists of three parts: Part 1: The NanoDefiner Framework and Tools, which covers the NanoDefiner framework, general information on measurement methods and performance criteria, and tools developed by NanoDefine such as a materials categorisation system, a decision support flow scheme and an e-tool. Part 2: Evaluation of Methods, which discusses the outcome of the evaluation of the nanomaterials characterisation methods for measuring size. Part 3: Standard Operating Procedures (SOPs), which presents the 23 Standard Operating Procedures developed within the NanoDefine project. In this combined document, these three parts are included as stand-alone reports, each having its own abstract, table of contents, page, table and figure numbering, and references.
The present series of reports, the NanoDefine Methods Manual, has been developed within the NanoDefine project 'Development of an integrated approach based on validated and standardized methods to support the implementation of the EC recommendation for a definition of nanomaterial', funded by the European Union's 7th Framework Programme, under grant agreement 604347.
In 2011 the European Commission (EC) published a recommendation for a definition of the term 'nanomaterial', the EC NM Definition, as a reference to determine whether an unknown material can be considered as a 'nanomaterial' for regulatory purposes1. One challenge is the development of methods that reliably identify, characterize and quantify nanomaterials (NM) both as substances and in various products and matrices.
The overall goal of NanoDefine was to support the implementation of the EC NM Definition. It can also support the implementation of any NM definition based on particle size. The project has developed an integrated approach, which allows identifying any material as a nano- or not a nanomaterial according to the EC NM Definition. NanoDefine explicitly supported the governance challenges associated with the implementation of legislation concerning nanomaterials by:
- addressing the issues on availability of suitable measuring techniques, reference materials, validated methods, acceptable to all stakeholders (authorities, policy makers, commercial firms),
- developing an integrated and interdisciplinary approach and a close international co-operation and networking with academia, commercial firms and standardization bodies.
Thus, the NanoDefine Methods Manual provides guidance on practical implementation of the EC NM Definition throughout the nanomaterial characterization process, and on the characterization techniques employed as well as their application range and limits. It assists the user in choosing the most appropriate measurement method(s) to identify any substance or mixture for a specific purpose, according to the EC NM Definition of a nanomaterial. The NanoDefine project also explored how to assess a material against the criteria of the definition through proxy solutions, i.e. by applying measurement techniques that indirectly determine the x50. Those findings were developed through empirically based scientific work and are included in Part 1 of this Manual. As they go beyond the text of the EC NM Definition, they may be used as practical approach to indicate whether a material is a nanomaterial or not, but keeping in mind that they should not be taken as recommendation for the implementation of the EC NM Definition in a regulatory context.
The NanoDefine Methods Manual consists of the following three parts:
Part 1: The NanoDefiner Framework and Tools
Part 2: Evaluation of Methods
Part 3: Standard Operating Procedures (SOPs)
Part 1 covers the NanoDefiner framework, general information on measurement methods and performance criteria and tools developed by NanoDefine such as a materials categorisation system, a decision support flow scheme and an e-tool.
Part 2 discusses the outcome of the evaluation of the nanomaterials characterisation methods for measuring size.
Part 3 presents the 23 Standard Operating Procedures developed within the NanoDefine project.
The current document is part 1.
The present series of reports, the NanoDefine Methods Manual, has been developed within the NanoDefine project 'Development of an integrated approach based on validated and standardized methods to support the implementation of the EC recommendation for a definition of nanomaterial', funded by the European Union's 7th Framework Programme, under grant agreement 604347.
In 2011 the European Commission (EC) published a recommendation for a definition of the term 'nanomaterial', the EC NM Definition, as a reference to determine whether an unknown material can be considered as a 'nanomaterial' for regulatory purposes1. One challenge is the development of methods that reliably identify, characterize and quantify nanomaterials (NM) both as substances and in various products and matrices.
The overall goal of NanoDefine was to support the implementation of the EC NM Definition. It can also support the implementation of any NM definition based on particle size. The project has developed an integrated approach, which allows identifying any material as a nano- or not a nanomaterial according to the EC NM Definition. NanoDefine explicitly supported the governance challenges associated with the implementation of legislation concerning nanomaterials by:
- addressing the issues on availability of suitable measuring techniques, reference materials, validated methods, acceptable to all stakeholders (authorities, policy makers, commercial firms),
- developing an integrated and interdisciplinary approach and a close international co-operation and networking with academia, commercial firms and standardization bodies.
Thus, the NanoDefine Methods Manual provides guidance on practical implementation of the EC NM Definition throughout the nanomaterial characterization process, and on the characterization techniques employed as well as their application range and limits. It assists the user in choosing the most appropriate measurement method(s) to identify any substance or mixture for a specific purpose, according to the EC NM Definition of a nanomaterial. The NanoDefine project also explored how to assess a material against the criteria of the definition through proxy solutions, i.e. by applying measurement techniques that indirectly determine the x50. Those findings were developed through empirically based scientific work and are included in Part 1 of this Manual. As they go beyond the text of the EC NM Definition, they may be used as practical approach to indicate whether a material is a nanomaterial or not, but keeping in mind that they should not be taken as recommendation for the implementation of the EC NM Definition in a regulatory context.
The NanoDefine Methods Manual consists of the following three parts:
Part 1: The NanoDefiner Framework and Tools
Part 2: Evaluation of Methods
Part 3: Standard Operating Procedures (SOPs)
Part 1 covers the NanoDefiner framework, general information on measurement methods and performance criteria and tools developed by NanoDefine such as a materials categorisation system, a decision support flow scheme and an e-tool.
Part 2 discusses the outcome of the evaluation of the nanomaterials characterisation methods for measuring size.
Part 3 presents the 23 Standard Operating Procedures developed within the NanoDefine project.
The current document is part 2.
The present series of reports, the NanoDefine Methods Manual, has been developed within the NanoDefine project 'Development of an integrated approach based on validated and standardized methods to support the implementation of the EC recommendation for a definition of nanomaterial'1 funded by the European Union's 7th Framework Programme, under grant agreement 604347.
In 2011 the European Commission (EC) published the recommendation (2011/696/EU) for a definition of the term 'nanomaterial'1, the EC NM Definition, as a reference to determine whether an unknown material can be considered as a 'nanomaterial' for regulatory purposes. One challenge is the development of methods that reliably identify, characterize and quantify nanomaterials (NM) both as substances and in various products and matrices.
The overall goal of NanoDefine was to support the implementation of the EC NM Definition. It can also support the implementation of any NM definition based on particle size. The project has developed an integrated approach, which allows identifying any material as a nano or non-nano material according to the EC NM Definition. NanoDefine explicitly supported the governance challenges associated with the implementation of legislation concerning nanomaterials by:
- addressing the issues on availability of suitable measuring techniques, reference materials, validated methods, acceptable to all - developing an integrated and interdisciplinary approach and a close international co-operation and networking with academia, commercial firms and standardization bodies.
Thus, the NanoDefine Methods Manual provides guidance on practical implementation of the EC NM Definition throughout the nanomaterial characterization process, and on the characterization techniques employed as well as their application range and limits. It assists the user in choosing the most appropriate measurement method(s) to identify any substance or mixture for a specific purpose, according to the EC NM Definition of a nanomaterial. The NanoDefine project also explored how to assess a material against the criteria of the definition through proxy solutions, i.e. by applying measurement techniques that indirectly determine the D50. Those findings were developed through empirically based scientific work and are included in Part 1 of this Manual. As they go beyond the text of the EC NM Definition, they may be used as practical approach to indicate whether a material is a nanomaterial or not, but keeping in mind that they should not be taken as recommendation for the implementation of the EC NM Definition in a regulatory context.
The NanoDefine Methods Manual consists of the following three parts:
Part 1: The NanoDefiner Framework and Tools
Part 2: Evaluation of Methods
Part 3: Standard Operating Procedures (SOPs)
Part 1 covers the NanoDefiner framework, general information on measurement methods and performance criteria and tools developed by NanoDefine such as a materials categorisation system, a decision support flow scheme and an e-tool.
Part 2 discusses the outcome of the evaluation of the nanomaterials characterisation methods for measuring size.
Part 3 presents the 23 Standard Operating Procedures developed within the NanoDefine project. The current document is part 3.
The image designed by Natalia Cano Murillo and colleagues shows the cross section of a ternary composite (boehmite/polycarbonate/epoxy, 80μm x 80μm). The surface was measured by AFM kelvin probe microscopy, yielding the surface potential which is shown as 3D‐surface and contour lines. The sample was further subjected to AFM force spectroscopy with a lateral resolution of 1μm², yielding the local Young's modulus, projected in false colors on the 3D surface. The ternary system, containing boehmite nanoparticles, shows a broad distribution of modulus, desirable for optimized macroscopic mechanical properties, such as high stiffness as well as toughness.
The present study addresses the capability of measurement of relative particle number concentration by scanning electron microscopy for model bimodal silica and gold samples prepared in the frame of the European research project “nPSize - Improved traceability chain of nanoparticle size measurements” as candidate reference nanoparticles.
In this paper one refined approach is applied to determine the exact orientation of bipyramidal TiO2 nanoparticles prepared with good dispersion as almost isolated particles on a carbon TEM grid. The advantages of the recently developed high-throughput Transmission Kikuchi Diffraction (TKD) are used to identify quickly and reliably the geometrical orientation of the crystalline TiO2 nanoparticle bipyramids (anatase) on a statistically relevant number of particles.
In this contribution different ways are explored with the aim to generate suitable training data for ‘non-ideal’ samples using various approaches, e.g., computer-generated images or unsupervised learning algorithms such as generative adversarial networks (GANs). We used these data to train simple CNNs to produce segmentation masks of SEM images and tested the trained networks on real SEM images of complex nanoparticle samples. The novel use of CNN for the automated analysis of the size of nanoparticles of complex shape and with a high degree of agglomeration has proved to be a promising tool for the evaluation of particle size distribution on a large number of constituent particles. Further development and validation of the preliminary model, respectively larger training and validation data sets are necessary.
Based on practical examples of analysis with Electron Microscopy and Energy-Dispersive X-ray Spectroscopy, the minimum information requirements for reliable and reproducible nanomaterial characterization data such as particle size and shape distribution and elemental analysis are presented and discussed.
This presentation is structured in two parts: i) Hybrid metrology by combining SEM with AFM (N. Feltin) and ii) hybridization and corelative microscopy by SEM, STEM-in-SEM, TEM, EDS, Auger Electron Microscopy, TKD and more (D. Hodoroaba).
The first part is focused on the metrological part of the hybrid measurement SEM-AFM, the second part offers some further possibilities of correlative microscopy of nanoparticles based on practical examples.
The main outcomes of the EMPIR project nPSize are presented and the suitability of the new capabilities (e.g. reference materials, measurement procedures, VAMAS inter-laboratory comparisons) to be standardized and implemented in accredited analytical laboratories is discussed. Complementation and/or filling gaps of published and ongoing standardisation projects on size, shape and number concentration measurements under ISO/TC 229/JWG 2 are offered.
You Ask – ACEnano Replies
(2020)
The workshop starts with introductory information about the workshop and the H2020 project ACEnano, followed by two expert round tables, focussing on how the project could address regulator and industry needs, respectively. This is be followed by parallel sessions on tools (based on preferences expressed by those registered to attend, see “Questions”) and finally a question-and-answer session with the attendees.
The experts invited in Round Table 1 have been prepared to answer to questions related to obstacles and advantages for stakeholders such as SMEs to use the ACEnano approaches/tools. Standardisation needs are discussed.
One of the objectives of the EU Project EC4SafeNano (European Centre for Risk Management and Safe Innovation in Nanomaterials & Nanotechnologies) was to test and benchmark the services in order to check their relevance to address identified stakeholder needs, but also to evaluate the governance of the structure delivering the proposed services. The aim is to demonstrate the technical relevance of the services and the overall open structure organisation, including governance rules and operating procedures, by answering relevant identified questions (case studies) selected by a panel of stakeholders. Therefore, a significant part of the project will be devoted to this demonstration of the operational and functional basis of the organized network.
The test material EDS-TM001 together with an accompanying software package, “EDX spectrometer check”, have been made available in 2009 by BAM to be employed by EDS (energy-dispersive X-ray spectrometer) users to check the performance of an EDS attached to the SEM. Particularly for test laboratories operating under accreditation schemes like ISO/IEC 17025, a periodical control of the critical instrumental parameters in end-user laboratories is required. With EDS-TM001 or EDS-TM002 (second generation) test material, this periodical check is simplified to the acquisition of only one 10 kV spectrum. The software “EDX spectrometer check” is destined to evaluate automatically this spectrum and determine the performance of the EDS in terms of energy resolution and calibration, as well as possible alteration of low-energy Efficiency due to detector contamination. Energy resolution can be compared with the specified values according to the international ISO standard ISO 15632:2012. EDS-TM is a synthetic material consisting of a 6 μm thick layer of C, Al, Mn, Cu and Zr deposited on a steel (in case of EDS-TM001) or silicon (in case of EDS-TM002) substrate. The chemical composition of EDS-TM was chosen such as to give nearly equal intensities of the low energy lines in a 10 kV spectrum, thus, making it very sensitive against spectrometer efficiency changes. Meanwhile, about 150 laboratories use the EDS-TM001 or EDS-TM002 test material for the periodical check of their EDS. A detailed description of the test material and software together with examples of application was published recently. New results and gained experiences will be presented as well. When the FWHM of the X-ray lines in the EDS-TM spectrum are determined, the spectrum background must be subtracted accurately. The applied physical background subtraction procedure is robust and takes into account the transmission of the detector window. While the previous version considers only Moxtek AP windows, the new version includes selection of silicon Nitride window and the case of windowless detector. Moreover, the new version allows importing of spectra in Bruker spx-format and EMSA/MSA files from EDAX TEAM software.
Windowless detectors have been also tested demonstrating long-term stability after repeated heating and cooling cycles. In this case, the appropriate Background subtraction is decisive for accurate detector characterization. Detailed results will be presented.
It was demonstrated in the past that the electron probe microanalysis (EPMA) can be applied to determine accurately both elemental composition and thickness of thin films by using the dedicated software package for thin film analysis Stratagem. A relatively small number of film materials such as pure metallic films of platinum and nickel, binary alloys of Fe-Ni, and Pt-Ni-Co ternary alloy films has been reported in literature as working successfully. Further, the software can be applied ‘inversely’, i.e., by feeding it with the thickness of the film and using the determined mass coating, one can easily calculate the film density, which for porous layers leads us to the true film porosity.
The present study repeats measurements on an already tested system of Fe-Ni thin films on silicon and reports for the first-time results of analysis on Si-Ge thin films deposited on a non-conductive aluminium oxide substrate. Standard-based and standardless EPMA (with EDS) results were used in combination with Stratagem for the quantification.
Further, X-ray fluorescence analysis (XRF) can be used for the determination of elemental composition and thickness of such films as well. In this case, XRF with a μ-focus X-ray source (μ-XRF) attached to a SEM was applied. For quantification, a fundamental parameter (FP) approach has been used to calculate standard-based and standardless results. Compared to EPMA, XRF has a larger information depth and a higher elemental sensitivity because of a generally lower background.
Both thin film systems have been chosen as samples of an international round robin test (RRT) organised in the frame of standardisation technical committee ISO/TC 201 ‘Surface chemical analysis’, under the lead of KRISS. The main objective of the RRT is to compare the results of atomic fractions of Fe1-xNix and Si1-xGex alloy films obtained by different surface Analysis techniques, such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and secondary ion mass spectrometry (SIMS) applied in the depth-profiling operation mode.
Five samples of different atomic fractions of each thin film system, i.e., Fe1-xNix and Si1-xGex, have been grown by ion beam sputter deposition on silicon and Al2O3 wafers, respectively. Reference FeNi and SiGe films with well-known elemental composition and thickness have been also supplied for standard-based analysis. The atomic fractions of all the samples including the references have been certified by RBS (Rutherford backscattering spectrometry) and ICP-AES (inductively coupled plasma atomic emission spectroscopy).
Porous materials play an important role in several fields of technology, especially for energy applications like photovoltaics, electrolysis or batteries. The activity of porous films is affected by properties like porosity, film thickness, chemical composition of the material, as well as the crystallinity of the framework. The complex morphology of such porous films constitutes a challenge even for modern analytical techniques and requires new approaches employing the combination/complementation of data of different analytical methods. In this contribution, we characterise thin mesoporous iridium-titanium mixed oxide film properties by electron probe microanalysis (EPMA) with energy-dispersive X-ray spectroscopy (EDS) at an SEM.
Mesoporous iridium oxide - titanium oxide (IrOx-TiOx) films were prepared via dip-coating of a solution containing a triblock-copolymer as structure-directing agent, an iridium precursor as well as a titanium precursor in ethanol. IrOx-TiOx films were synthesized with different amounts of iridium and calcined in air. The SEM micrographs reveal for all films the achievement of a well-ordered mesoporous structure and homogeneous films with thicknesses between 67 nm and 152 nm.
For the determination of film elemental composition and porosity, EPMA can be used as part of a combined SEM/EDS/STRATAGem analysis. Elemental compositions and mass depositions (in μg cm-2) of IrOx-TiOx films were calculated with the thin film analysis Software STRATAGem via k-values measured with SEM/EDS. Pure bulk Ir, TiO2 and Si were measured as references. The average density of the films was obtained from the mass Deposition and the film thickness as measured by cross-section SEM. The porosity was then extracted from the measured average film density divided by a theoretical bulk density. The latter is calculated from the weight fractions of IrOx and TiOx as determined with STRATAGem and the bulk mass densities of IrO2 and TiO2 (rutil) from literature.
The fitting results of the k-values from the STRATAGem software, which are in fair agreement with the measured k-values.
The application of the SEM/EDS/STRATAGem approach for accurate porosity determination on pure mesoporous TiOx films and pure porous IrOx films has been recently demonstrated.
The porosities of pure IrOx, TiOx and mixed IrOx-TiOx films in this study have been determined. The contribution will assess in detail the advantages and limitations of the combined SEM/EDS/STRATAGem analysis for the morphology and porosity of thin metal oxide films. Moreover, the comparison with other measurement techniques and the combination of datasets from multiple measurements will be discussed.
Microbeam analysis data are of continuously improving quality, this owing mainly to developments in instrumentation (hardware and software) and computer performance. The knowledge and skills of the operators must be also kept correspondingly updated. To be deemed as technically competent, the laboratories must be accredited according to an accreditation scheme, mostly following ISO/IEC 17025.
International standards are able to provide requirements, specifications, guidelines or characteristics of methods, instruments or samples with the final goal that these can be used consistently in accredited laboratories. In the field of electron microscopy and microbeam Analysis standardisation and metrology are terms that are encountered rather seldom at major conferences and scientific publications. Several ISO standards already published and used successfully by a large part of the electron microscopy and microbeam analysis community. For example, file formats such as EMSA/MSA for spectral-data exchange or tagged image file format (TIFF) for SEM images; procedures for the specification of X-ray spectrometers, the specification of certified reference materials (CRMs), and for measurement of average grain size by electron backscatter diffraction (EBSD); and guidelines for calibrating image magnification in SEM or TEM. A main task of ISO technical committee TC 202 ‘Microbeam Analysis’ is to identify feasible projects/proposals needed to be developed into new international standards, particularly in respect to recent technology, such the silicon drift detector (SDD).
As far as the metrological aspects are regarded, The International Bureau of Weights and Measures (BIPM) through the Consultative Committee for the Amount of Substance (CCQM) is concerned with the metrological aspect in Chemistry and Biology. In particular, the Surface Analysis Working Group (SAWG) assists in identifying and establishing inter-laboratory work to test the consistency as well as to improve the traceability of spatially resolved chemical surface analysis at the micro and nanoscale. Examples of recent projects on quantitative microbeam analysis at low energies, such as the quantification of light elements such as carbon and nitrogen will be presented.
The significant sources of measurement uncertainty will be emphasized. These are: quality of the unknown and the reference materials used, the quantification model, instrumental parameters like take-off-angle, spectrometer efficiency, and particularly the beam current. The crucial importance of working with uniform and well-defined measurement and data evaluation protocols will be discussed in compliance with the ISO document “Guide to the expression of uncertainty in measurement (GUM)”.
Another international platform where pre-standardisation work can be organised is VAMAS (Versailles Project on Advanced Materials and Standards). International collaborative Projects aim at providing the technical basis for harmonised measurements, testing, specifications, and standards to be further developed at ISO level. One key point of VAMAS activities is constituted by inter-laboratory comparisons for high-quality data. In the field of microbeam analysis, the technical working area (TWA) 37 Quantitative Microstructural Analysis deals with corresponding projects. Good ideas, e.g., on analysis at low energies, are particularly encouraged by directly contacting the author. Support and guidance will be supplied.
Measurement of elemental composition of Fe1-xNix and Si1-xGex alloy thin films by EMPA and µ-XRF
(2019)
It was demonstrated in the past that the electron probe microanalysis (EPMA) can be applied to determine accurately both elemental composition and thickness of thin films by using the dedicated software package for thin film analysis Stratagem. A relatively small number of film materials such as pure metallic films of platinum and nickel, binary alloys of Fe-Ni, and Pt-Ni-Co ternary alloy films has been reported in literature as working successfully. Further, the software can be applied ‘inversely’, i.e., by feeding it with the thickness of the film and using the determined mass coating, one can easily calculate the film density, which for porous layers leads us to the true film porosity.
The present study repeats measurements on an already tested system of Fe-Ni thin films on silicon and reports for the first-time results of analysis on Si-Ge thin films deposited on a non-conductive aluminium oxide substrate. Standard-based and standardless EPMA (with EDS) results were used in combination with Stratagem for the quantification.
Further, X-ray fluorescence analysis (XRF) can be used for the determination of elemental composition and thickness of such films as well. In this case, XRF with a μ-focus X-ray source (μ-XRF) attached to a SEM was applied. For quantification, a fundamental parameter (FP) approach has been used to calculate standard-based and standardless results. Compared to EPMA, XRF has a larger information depth and a higher elemental sensitivity because of a generally lower background.
Both thin film systems have been chosen as samples of an international round robin test (RRT) organised in the frame of standardisation technical committee ISO/TC 201 ‘Surface chemical analysis’, under the lead of KRISS. The main objective of the RRT is to compare the results of atomic fractions of Fe1-xNix and Si1-xGex alloy films obtained by different surface Analysis techniques, such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and secondary ion mass spectrometry (SIMS) applied in the depth-profiling operation mode.
Five samples of different atomic fractions of each thin film system, i.e., Fe1-xNix and Si1-xGex, have been grown by ion beam sputter deposition on silicon and Al2O3 wafers, respectively. Reference FeNi and SiGe films with well-known elemental composition and thickness have been also supplied for standard-based analysis. The atomic fractions of all the samples including the references have been certified by RBS (Rutherford backscattering spectrometry) and ICP-AES (inductively coupled plasma atomic emission spectroscopy).
The 44th Meeting of the Versailles Project on Advanced Materials and Standards (VAMAS) Steering Committee has just taken place at NIST in Boulder (CO, USA). BAM participates with significant contributions in Technical Working Areas on nanoparticle and surface chemistry characterization, but also has positioned itself to new global material challenges and trends in the developement of advanced materials and their characterization, such as thermal properties, self-healing materials, and micro- and nanoplastic.
The test material EDS-TM001 together with an accompanying software package, “EDS spectrometer check”, have been made available in 2009 by BAM to be employed by EDS (energy-dispersive X-ray spectrometer) users to check the performance of an EDS with a SEM. With EDS-TM001/002 test material, this periodical check is simplified to the acquisition of only one 10 kV spectrum. The software “EDS spectrometer check” is destined to evaluate automatically this spectrum and determine the EDS performance in terms of energy resolution and calibration, as well as possible alteration of low-energy efficiency due to detector contamination. Energy resolution can be compared with the specified values according to the international ISO standard ISO 15632:2012.
EDS-TM is a synthetic material consisting of a 6 μm thick layer of C, Al, Mn, Cu and Zr deposited on a steel (EDS-TM001) or silicon (EDS-TM002) substrate. The chemical composition of EDS-TM was chosen such as to give nearly equal intensities of the low energy lines in a 10 kV spectrum, thus, making it very sensitive against spectrometer efficiency changes. New results and gained experiences will be presented.
When the FWHM of the X-ray lines in the EDS-TM spectrum are determined, the spectrum Background must be subtracted accurately. The applied physical background subtraction procedure is robust and considers the transmission of the detector window. While the previous version considers only Moxtek AP windows, the new software version includes selection of silicon nitride window and the case of windowless detector.
Porous materials play an important role in several fields of technology, especially for energy applications like photovoltaics, electrolysis or batteries. The activity of thin porous films is affected by properties like porosity, film thickness, chemical composition of the material as well as the homogenous dispersion of the active species within the porous matrix. The complex morphology of such porous films constitutes a challenge even for modern analytical techniques and requires new approaches employing the combination/complementation of data of different analytical methods. In this contribution we characterize thin mesoporous iridium-titanium mixed oxide film properties by complementary analysis of SEM/EDS, ToF-SIMS, NanoSIMS, AES and spectroscopic ellipsometry.
Mesoporous iridium oxide - titanium oxide (IrOx-TiOx) films can be prepared by a well-established Synthesis route via soft-templating. IrOx-TiOx films are very sensitive to the conditions of synthesis. Analysis by SEM and NanoSIMS imaging suggests IrOx-TiOx films with and without a homogenous dispersion of IrOx within the TiOx film matrix under different synthesis conditions.
Auger electron spectroscopy (AES) analysis in the depth-profile mode as well as cross-section line-scan AES measurements of an inhomogeneous IrOx-TiOx film indicate the presence of an IrOx-rich Phase dispersion both at the surface of IrOx-TiOx film as well as within the film.
The contribution will assess in detail the sensitivity of the synthesis conditions and the characterization of the thin metal oxide films. Moreover, the correlation between and comparison to other measurement techniques will be discussed.
New reference material candidates for traceable size measurement of nonspherical nanoparticles
(2019)
Size measurement of nanoparticles (NP) becomes a challenging analytical problem when non-spherical shapes must be traceably measured. However, most industrial NPs have irregular shapes and broad size distribution making it often more complex to follow European regulatory to identify a material as a nanomaterial according to which accurate measurement of the smallest dimension and its size Distribution is necessary.
The European research project nPSize - Improved traceability chain of nanoparticle size measurements aims to fill this gap by developing potential non-spherical reference nanoparticles, measurement procedures and physical modelling to improve the traceability chain, comparability and compatibility for NP size measurements between different methods. Therefore, new model NP with well-controlled shape has been synthesized and are supposed to be systematically characterized using the traceable methods scanning/transmission electron microscopy, atomic force microscopy and small angle X-ray scattering.
Following NP candidates are under investigation with respect to their homogeneity and stability: (i) titania nanoplatelets (10-15 nm thickness x 50-100 nm lateral), (ii) titania bipyramides (~60 nm length x 40 nm width), (iii) titania acicular particles (100 nm length x 15-20 nm width; aspect ratio 5.5/6), (iv) gold nanorods (~10 nm width x 30 nm length), and (v) gold nanocubes (~55 nm x 55 nm x 55 nm). In addition, sample preparation procedures as well as measurement analysis procedures with evaluation of appropriate measurands and descriptors for each material class and method are being developed to support standardization. To underpin the traceability of the size measurement of nonspherical NP, physical modelling of the signals in e.g. electron microscopy techniques will be used and in combination, the implementation of machine learning is aimed to facilitate measurement Analysis procedures, especially regarding the accurate thresholding/segmentation of the NPs.
Analysis of Elemental Composition of Fe1-xNix and Si1-xGex Alloy Thin Films by EPMA and μ-XRF
(2019)
The present study reports on measurements on thin Fe-Ni films on silicon and first-time results of analysis on Si-Ge thin films deposited on a non-conductive aluminium oxide Substrate by electron probe microanalysis (EPMA). Standard-based and standardless EPMA (with EDS) results were used in combination with the thin film analysis software Stratagem for the quantification.
Further, X-ray fluorescence analysis (XRF) can be used for the determination of elemental composition and thickness of such films as well. In this case, XRF with a μ-focus X-ray source (μ-XRF) attached to a SEM was applied. For quantification, a fundamental parameter (FP) approach has been used to calculate standard-based and standardless results.
Both thin film systems have been chosen as samples of an international round robin test (RRT) organised in the frame of standardisation technical committee ISO/TC 201 ‘Surface chemical analysis’, under the lead of KRISS. The main objective of the RRT is to compare the results of atomic fractions of Fe1-xNix and Si1-xGex alloy films obtained by different surface Analysis techniques, such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and secondary ion mass spectrometry (SIMS) applied in the depth-profiling operation mode.
Five samples of different atomic fractions of each thin film system, i.e., Fe1-xNix and Si1-xGex, have been grown by ion beam sputter deposition on silicon and Al2O3 wafers, respectively. Reference FeNi and SiGe films with well-known elemental composition and thickness have been also supplied for standard-based analysis. An excellent agreement has been obtained between the atomic fractions determined by EPMA and µ-XRF with the KRISS certified values.zeige mehr
There are different ways how to prove the quality of the analytical results obtained in a laboratory, e.g. use of validated standard operation procedures, participation in proficiency testing exercises, use of certified reference materials, etc. International standards provide requirements, specifications, Guidelines or characteristics of methods, instruments or samples with the final goal that these can be used consistently in accredited laboratories. In the field of electron microscopy and microbeam analysis standardization and metrology are terms which are encountered rather seldom at major conferences and scientific publications. Nevertheless, spectra formats like EMSA/MSA for spectral-data exchange or tagged image file format (TIFF) for SEM, guidelines for performing quality assurance procedures or for the specification of X-ray spectrometers as well as of certified reference materials (CRMs) in EPMA, or measurement of average grain size by electron backscatter diffraction (EBSD), or guidelines for calibrating image magnification in SEM or TEM are ISO standards already published and used successfully by a large part of the electron microscopy and microbeam analysis community. A main and continuous task of ISO/TC 202 and its subcommittees is to identify and evaluate feasible projects/proposals to be developed into new international standards, particularly with respect to recent but established technology, such the silicon drift detector (SDD) EDS.
An international platform in the frame of which pre-standardization work can be organized is VAMAS (Versailles Project on Advanced Materials and Standards). International collaborative projects involving aim at providing the technical basis for harmonized measurements, testing, specifications, and standards to be further developed at ISO level. One key point of VAMAS activities is constituted by inter-laboratory comparisons for high-quality data. In the field of microbeam analysis, the technical working area (TWA) 37 Quantitative Microstructural Analysis deals with corresponding projects. Good ideas, e.g. on analysis of low-Z materials/elements and at low energies are particularly encouraged by directly contacting the author. Support and already available guidance will be supplied.