Filtern
Erscheinungsjahr
Dokumenttyp
Sprache
- Englisch (153)
Referierte Publikation
- ja (153) (entfernen)
Schlagworte
- Nanoparticles (29)
- EDX (23)
- SEM (21)
- EDS (12)
- Electron microscopy (11)
- XRF (10)
- EPMA (8)
- CCQM (7)
- Titanium dioxide (7)
- ToF-SIMS (6)
- Transmission (6)
- XPS (6)
- Elemental composition (5)
- Modelling (5)
- Sample preparation (5)
- T-SEM (5)
- TiO2 (5)
- High-resolution (4)
- Nanomaterials (4)
- Shape (4)
- Size (4)
- Spectroscopic ellipsometry (4)
- Thin films (4)
- WDX (4)
- X-ray scattering (4)
- X-rays (4)
- AES (3)
- Bisphenol A (3)
- CIGS (3)
- CRM (3)
- Calibration (3)
- Characterization (3)
- ED-EPMA (3)
- Image analysis (3)
- Interlaboratory comparison (3)
- Key comparison (3)
- Nano (3)
- Nanomaterial (3)
- Nanoparticle (3)
- Nanotechnology (3)
- Particle size (3)
- Porosity (3)
- Quantification (3)
- Quantum dots (3)
- Reference material (3)
- SEM/EDX (3)
- Size distribution (3)
- Standardization (3)
- TEM (3)
- X-ray optics (3)
- X-ray spectroscopy (3)
- X-ray tube (3)
- (mu-)XRF (2)
- Acceptance area (2)
- Advanced materials (2)
- Atomic force microscopy (2)
- Auger Electron Spectroscopy (2)
- Characterisation (2)
- Composites (2)
- Concentration (2)
- Decision support (2)
- Energy dispersive X-ray spectroscopy (EDX) (2)
- Energy-dispersive X-ray spectrometer (EDS) (2)
- FWHM (2)
- Fenton (2)
- Film thickness (2)
- Focal distance (2)
- GDS (2)
- Geometrical collection efficiency (2)
- Imaging (2)
- Ionic liquids (2)
- K-values (2)
- Katalysator (2)
- Micro-focus-XRF (2)
- Micropollutants (2)
- Monte-Carlo simulation (2)
- Morphology (2)
- Multi-sample analysis (2)
- Nanomaterial classification (2)
- Parallelising mode (2)
- Particle (2)
- Performance check (2)
- Photooxidation (2)
- Pilot study (2)
- Polycapillary X-ray optics (2)
- Porous materials (2)
- Quantum yield (2)
- Regulation (2)
- Roughness (2)
- SAXS (2)
- SEM/EDS (2)
- STRATAGem (2)
- Scanning electron microscope (SEM) (2)
- Scanning electron microscopy (SEM) (2)
- Semi-lens (2)
- SiO2 (2)
- Size measurement (2)
- Spectrometer efficiency (2)
- Standardisation (2)
- Standards (2)
- Surface analysis (2)
- Surface chemical analysis (2)
- Surface functionalization (2)
- Test material (2)
- Thin film (2)
- VAMAS (2)
- WD-EPMA (2)
- Wastewater (2)
- X-ray photoelectron spectroscopy (2)
- X-ray tube spectrum (2)
- ACEnano (1)
- AFM (1)
- Absolute X-ray spectrum (1)
- Absorption spectrometry (1)
- Abwasser (1)
- Advanced material (1)
- AgInS (1)
- Agglomeration/aggregation (1)
- Alloy films (1)
- Amorphous phases (1)
- Amperometry (1)
- Analytical SEM (1)
- Anti-corrosion (1)
- Anti-corrosion coatings (1)
- Apatite (1)
- Aqueous synthesis (1)
- Artificial intelligence (1)
- Auger Electron Spectroscopy (AES) (1)
- Austenitic phase (1)
- Automated image analysis (1)
- Automation (1)
- BAM-L200 (1)
- Bearing steel (1)
- Benchmarking (1)
- Biofilms (1)
- Biomedical application (1)
- Bipyramid (1)
- Bisphenol A degradation (1)
- Blue pigment (1)
- Boehmite (1)
- Boehmite nanoparticles (1)
- Brunauer-Emmett-Teller (1)
- CEN (1)
- Caenorhabdtis elegans (1)
- Calcium monofluoride (1)
- Calcium titanium phosphate (1)
- Calibrated SEM/EDS (1)
- Carbamazepine (1)
- Catalysis (1)
- Catalytic wet peroxide oxidation (1)
- Cationic photocuring (1)
- Cerium oxide (1)
- Certification (1)
- Certified reference material (1)
- Certified reference nanomaterials (1)
- Characterisation techniques (1)
- Characterization of catalysts (1)
- Charge (1)
- Chemistry (1)
- Classification (1)
- Coated/Layered Reference Materials (1)
- Coating (1)
- Coatings (1)
- Coimbra (1)
- Complementary methodology and metrology (1)
- Complex-shape (1)
- Composition (1)
- Compton scattering (1)
- Controlled morphology (1)
- Controlled periodic illumination (1)
- Controlled-shape (1)
- Core-shell nanoparticles (1)
- Core-shell particles (1)
- Core–shell particles (1)
- Correlative analysis (1)
- Crater shape (1)
- Cross-sectioning (1)
- Crosslinking density (1)
- Crystal growth (1)
- Crystallinity (1)
- Cu-Au alloy (1)
- Cyclic voltammetry (1)
- Cycloaliphatic epoxy oligosiloxane (1)
- Cyclometalated iridium (III) complexes (1)
- Cytotoxicity (1)
- DSSC (1)
- Data correlation (1)
- Data readiness level (1)
- Definition (1)
- Density (1)
- Depth profiling (1)
- Depth resolution (1)
- Detection efficiency (1)
- Detection limits (1)
- Detector efficiency (1)
- Dodecanethiol (1)
- Duplex stainless steel (1)
- EC nanomaterial definition (1)
- EDS detector (1)
- EDS performance test (1)
- EDS-TM001 (1)
- EDS-TM002 (1)
- ESR (1)
- Effective area (1)
- Effective solid angle (1)
- Electrocatalysis (1)
- Electrochemical catalysts (1)
- Electrochemistry (1)
- Electrolysis (1)
- Electron probe microanalysis (1)
- Electrospary (1)
- Electrospun nanocomposite fiber (1)
- Emission spectroscopy (1)
- Endocrine disruptor (1)
- Energy dispersive (1)
- Energy dispersive X-ray spectrometry (1)
- Energy dispersive X-ray spectroscopy (1)
- Energy dispersive electron probe microanalysis (ED-EPMA) (1)
- Energy resolution (1)
- Energy-dispersive X-ray spectroscopy (EDX, XEDS) (1)
- Environment (1)
- Epoxy (1)
- Epoxy conversion degree (1)
- Epoxy nanocomposites (1)
- European Centre (1)
- Expert system (1)
- F- doping (1)
- FAIRification (1)
- Fe-Ni (1)
- Fe-Ni alloy (1)
- Fe-Ni alloy film (1)
- Fe-based highly active ionic liquids (1)
- FeNi (1)
- Fenton oxidation (1)
- Ferritic phase (1)
- Films (1)
- Firing temperature (1)
- Five iron oxalate core–shell magnetite nanoparticles catalysts are evaluated as magnetic heterogeneous (1)
- Fluoride (1)
- Focused ion beam tomography (1)
- Functionalized graphene (1)
- GD-OES (1)
- GDMS (1)
- GDOES (1)
- Genotoxic and oxidative damage (1)
- Governance (1)
- Graphite furnace (1)
- Grimm type glow discharge (1)
- HFM plasma SNMS (1)
- HR-CS-MAS (1)
- Hard-energy X-ray photoelectron spectroscopy (1)
- High-resolution scanning electron microscope (SEM) (1)
- High-resolution transmission in SEM (TSEM) (1)
- Hollow cathode (1)
- Homogeneity (1)
- Hybrid metrology (1)
- Hybrid metrology measurement (1)
- Hydrogen (1)
- Hydrogen evolution reaction (1)
- Hydrogen photoproduction (1)
- ISO (1)
- ISO 15632 (1)
- Identification (1)
- Image segmentation (1)
- Imaging surface analysis (1)
- Imaging surface chemical analysis (1)
- Immunoassay (1)
- In-situ SAXS/WAXS (1)
- Infrared nano AFM (1)
- Inter-laboratory comparison (1)
- Intermediate phases (1)
- Intermodulation (1)
- Intermodulation AFM (1)
- Interphase (1)
- Intrinsic OER activity (1)
- Iron oxide (1)
- K-rich Birnessite (K0.45MnO2) (1)
- Kramers background (1)
- Large area SDD (1)
- Large-area EDS (1)
- Laser ablation in liquid (1)
- Lateral resolution (1)
- Layer-by-layer deposition (1)
- Lifetime analysis (1)
- Ligand exchange (1)
- Limits of detection (1)
- Line scan (1)
- Lisbon (1)
- Low energy (1)
- Lubricated contact (1)
- Luminescent lifetime (1)
- Machine learning (1)
- Magic-sized cluster (1)
- Magnetic coreshell nanocatalysts (1)
- Magnetic nanocatalyst (1)
- Magnetische Nanopartikel (1)
- Magnetpartikel (1)
- Manufacturing (1)
- Mapping (1)
- Mass coverage (1)
- Mass deposition (1)
- Measurement uncertainty (1)
- Mechanical properties (1)
- Mesoporosity (1)
- Mesoporous iridium oxide films (1)
- Method development (1)
- Metrological traceability (1)
- Metrology (1)
- Micro- and nanocapsules (1)
- Micro-Raman imaging (1)
- Micro-XRF (1)
- Microanalysis (1)
- Microbially influenced corrosion (MIC) (1)
- Microcapsules (1)
- Microfocus x-ray source (1)
- Microwave-assisted synthesis (1)
- Mitigation (1)
- Mixed metal oxide (1)
- Monochromatic excitation (1)
- Multilayer (1)
- Nano-safety (1)
- NanoValid (1)
- Nanocapsules (1)
- Nanocatalysts (1)
- Nanocomposite (1)
- Nanocomposites (1)
- Nanomaterial analysis (1)
- Nanomaterial categorisation (1)
- Nanomaterial definition (1)
- Nanomaterial legislation (1)
- Nanomaterial regulation (1)
- Nanomechanical charecteisation (1)
- Nanomechanical properties (1)
- Nanometrology (1)
- Nanoparticle concentration (1)
- Nanoparticle structure (1)
- Nanopowder (1)
- Nanosafety (1)
- Nanoscale EDX analysis (1)
- Nanoscale T-SEM (1)
- Nanosheets (1)
- Nanotoxicology (1)
- Neural networks (1)
- Nitrides (1)
- Non-classical crystallization theory (1)
- Non-conductive layered samples (1)
- Non-destructive ambient analysis (1)
- Number-weighted median size (1)
- OECD (1)
- Ochratoxin A (1)
- One-pot synthesis (1)
- Optically active surfaces (1)
- Oxygen evolution reaction (1)
- Oxygen evolution reaction (OER) (1)
- Particle morphology (1)
- Particle size analysis (1)
- Particle size and shape distribution (1)
- Particle size distribution (1)
- Peak-to-background (1)
- Peak-to-noise (1)
- Perfluorooctanoic Acid (PFOA) (1)
- Phosphates (1)
- Photo-Fenton oxidation (1)
- Photocatalysis (1)
- Photodegradation (1)
- Photoelectrochemistry (1)
- Photon generation yield (1)
- Photoreforming (1)
- Physicochemical characterization (1)
- Platinum (1)
- Polarisation (1)
- Polyethylene glycol (1)
- Porosimetry (1)
- Portuguese glazed ceramics (1)
- Portuguese polychrome glazed pottery (1)
- Pphosphates (1)
- Quality assurance (1)
- Raman spectroscopy (1)
- Rayleigh scattering (1)
- Reactive azo dye degradation (1)
- Real-time infrared spectroscopy (1)
- Reference materials (1)
- Reference-free XRF (1)
- Removal (1)
- Reproducibility (1)
- Rheology (1)
- Risk asessment (1)
- RoHS (1)
- Round Robin (1)
- Ru dye sensitizer (1)
- SIMS (1)
- STEM-in-SEM (1)
- STRATAGEM (1)
- STXM (1)
- Sabatier (1)
- Scanning and transmission electron microscopies (1)
- Scanning electron microscopy (1)
- Scanning mobility particle size spectrometers (1)
- Scanning probe microscopy (1)
- Scattering (1)
- Secondary ion mass spectrometry (1)
- Semiconductor nanocrystals (1)
- Sensitivity (1)
- Sensitized magnetic nanocatalysts (1)
- Setup (1)
- Shape distribution (1)
- Shape-controlled nanoparticles (1)
- Shape-engineered (1)
- Sharpness (1)
- SiGe (1)
- SiO2 nano-aerosol size distribution (1)
- Side-window X-ray tube (1)
- Single nanoparticles (1)
- Singlet oxygen (1)
- Singulettsauerstoff (1)
- Size measurements (1)
- Small-angle X-ray scattering (1)
- Software (1)
- Sol-gel processing (1)
- Solar Cell (1)
- Solar concentrator (1)
- Solar energy (1)
- Solid angle (1)
- Solubility (1)
- Sonochemical synthesis (1)
- Spectral background (1)
- Spectrometer calibration (1)
- Spherical nanoparticles (1)
- Stability (1)
- Standard operation procedures (1)
- Standardless analysis (1)
- Stratagem (1)
- Strength (1)
- Strontium titanate (1)
- Struvite (1)
- Surface (1)
- Synthesis (1)
- TEM grid (1)
- TKD (1)
- TOF-SIMS mappings (1)
- TRL (1)
- TSEM (1)
- Ternary alloys (1)
- Test materials (1)
- Thermal analysis (1)
- Thermoplastics (1)
- Thermosets (1)
- Thickness (1)
- Thin film metrology (1)
- Thin mesoporous films (1)
- Thin-layer analysis (1)
- Thiols (1)
- Threshold (1)
- TiO2 films (1)
- Tiered (1)
- Titania (1)
- Titanium oxide (1)
- Trace elements (1)
- Traceability (1)
- Traceable nanoparticle size measurements; (1)
- Transition metal (1)
- Transition metals (1)
- Transmission Kikuchi diffraction (1)
- Transmission electron microscopy (1)
- Transmission in SEM (1)
- Transmission mode (1)
- Transmission scanning electron microscopy/microscope (TSEM, T-SEM, STEM) (1)
- Transmission-SEM (1)
- Trends (1)
- Uncertainty (1)
- VSSA (1)
- Volcano plot (1)
- Volume specific surface area (1)
- WDS (1)
- Water treatment (1)
- Wear particle analysis (1)
- X-ray Fluorescence (1)
- X-ray detectors (1)
- X-ray emission yield (1)
- X-ray fluorescence (1)
- X-ray fluorescence analysis (1)
- X-ray production yield (1)
- X-ray spectrometer (1)
- X-ray tube spectra (1)
- XANES (1)
- XPEEM (1)
- Xerogel (1)
- Yellow pigment (1)
- Zinc oxide (1)
- Zirconium (1)
- ZnSe (1)
- analytical service (1)
- k-values (1)
- layered system (1)
- mu-XRF (1)
- muXRF (1)
- rf system (1)
- rf-Glow discharge (1)
- silica nanoparticles (1)
- surface and in-depth inspection (1)
- titania nanoparticles (1)
- transmission mode (1)
Organisationseinheit der BAM
- 6 Materialchemie (59)
- 6.1 Oberflächen- und Dünnschichtanalyse (59)
- 1 Analytische Chemie; Referenzmaterialien (15)
- 1.2 Biophotonik (6)
- 1.8 Umweltanalytik (5)
- 6.3 Strukturanalytik (5)
- 6.6 Physik und chemische Analytik der Polymere (5)
- 5 Werkstofftechnik (4)
- P Präsident (4)
- P.0 Präsident und andere (4)
Paper des Monats
- ja (5)
Luminescence lifetimes are an attractive analytical method for detection due to its high sensitivity and stability. Iridium probes exhibit luminescence with long excited-state lifetimes, which are sensitive to the local environment. Perfluorooctanoic acid (PFOA) is listed as a chemical of high concern regarding its toxicity and is classified as a “forever chemical”. In addition to strict limits on the presence of PFOA in drinking water, environmental contamination from industrial effluent or chemical spills requires rapid, simple, accurate, and cost-effective analysis in order to aid containment. Herein, we report the fabrication and function of a novel and facile luminescence sensor for PFOA based on iridium modified on gold surfaces. These surfaces were modified with lipophilic iridium complexes bearing alkyl chains, namely, IrC6 and IrC12, and Zonyl-FSA surfactant. Upon addition of PFOA, the modified surfaces IrC6-FSA@Au and IrC12-FSA @Au show the largest change in the red luminescence signal with changes in the luminescence lifetime that allow monitoring of PFOA concentrations in aqueous solutions. The platform was tested for the measurement of PFOA in aqueous samples spiked with known concentrations of PFOA and demonstrated the capacity to determine PFOA at concentrations >100 μg/L (240 nM).
Reliable measurement of the size of polydisperse, complex-shaped commercial nanopowders is a difficult but necessary task, e.g., for regulatory requirements and toxicity risk assessment. Suitable methods exist for the accurate characterization of the size of non-aggregated, stabilized, spherical and monodisperse nanoparticles. In contrast, industrial nanoscale powders usually require dedicated sample preparation procedures developed for the analysis method of choice. These nano-powders tend to agglomerate and/or aggregate, a behavior which in combination with an innate broad particle size distribution and irregular shape often significantly alters the achievable accuracy of the measured size parameters. The present study systematically tests two commercially available nanoscale powders using different sample preparation methods for correlative analysis by scanning electron microscopy, dynamic light scattering, Brunauer–Emmet–Teller method and differential mobility analysis. One focus was set on the sample preparation by embedding nanoparticles in carbon-based hot-mounting resin. Literature on this topic is scarce and the accuracy of the data extracted from cross sections of these particles is unclearly stated. In this paper systematic simulations on the deviation of the size parameters of well-defined series of nanoparticles with different shapes from the nominal value were carried out and the contributing factors are discussed.
Although the use of noble metal catalysts can increase the efficiency of hydrogen evolution reaction, the process is still limited by the characteristics of the metal-hydrogen (M−H) bond, which can be too strong or too weak, depending on the metal employed. Studies revealed that the hydrogen affinity for the metal surface (i.e. H absorption/desorption) is regulated also by the potential at the metal nanoparticles. Through controlled periodic illumination (CPI) of a series of metal/TiO2 suspensions, here we demonstrated that an increase of the HER efficiency is possible for those photodeposited metals which have a Tafel slope below 125 mV. Two possible explanations are here reported, in both of them the M−H interaction and the metal covering level play a prominent role, which also depend on the prevailing HER mechanism (Volmer-Heyrovsky or Volmer-Tafel).
The new recommended definition of a nanomaterial, 2022/C 229/01, adopted by the European Commission in 2022, will have a considerable impact on European Union legislation addressing chemicals, and therefore tools to implement this new definition are urgently needed. The updated NanoDefiner framework and its e-tool implementation presented here are such instruments, which help stakeholders to find out in a straightforward way whether a material is a nanomaterial or not. They are two major outcomes of the NanoDefine project, which is explicitly referred to in the new definition. This work revisits the framework and e-tool, and elaborates necessary adjustments to make these outcomes applicable for the updated recommendation. A broad set of case studies on representative materials confirms the validity of these adjustments. To further foster the sustainability and applicability of the framework and e-tool, measures for the FAIRification of expert knowledge within the e-tool’s knowledge base are elaborated as well. The updated framework and e-tool are now ready to be used in line with the updated recommendation. The presented approach may serve as an example for reviewing existing guidance and tools developed for the previous definition 2011/696/EU, particularly those adopting NanoDefine project outcomes.
We present how mesoporosity can be engineered in transition metal phosphate (TMPs) materials in a template-free manner. The method involves a transformation of a precursor metal phosphate phase, called M-struvite (NH4MPO4·6H2O, M = Mg2+, Ni2+, Co2+, NixCo1-x2+). It relies on the thermal decomposition of crystalline M-struvite precursors to an amorphous and simultaneously mesoporous phase, which forms while degassing of NH3 and H2O. The temporal evolution of mesoporous frameworks and the response of the metal coordination environment were followed with in-situ and ex-situ scattering and diffraction, as well as X -ray spectroscopy. Despite sharing the same precursor struvite structure, different amorphous and mesoporous structures were obtained depending on the involved transition metal. We highlight the systematic differences in absolute surface area, pore shape, pore size, and phase transitions depending on a metal cation present in the analogous M-struvites. The amorphous structures of thermally decomposed Mg-, Ni- and NixCo1-x-struvites exhibit high surface areas and pore volumes (240 m²g-1 and 0.32 cm-3 g-1 for Mg and 90 m²g-1 and 0.13 cm-3 g-1 for Ni). We propose that the low-cost, environmentally friendly M-struvites could be obtained as recycling products from industrial and agricultural wastewaters. These waste products could be then upcycled into mesoporous TMPs through a simple thermal treatment for further applications, for instance, in (electro)catalysis.
The obvious benefits derived from the increasing use of engineered nano-, new, and advanced materials and associated products have to be weighed out by a governance process against their possible risks. Differences in risk perception (beliefs about potential harm) among stakeholders, in particular nonscientists, and low transparency of the underlying decision processes can lead to a lack of support and acceptance of nano-, new, and other advanced material enabled products. To integrate scientific outcomes with stakeholders needs, this work develops a new approach comprising a nine-level, stepwise categorization and guidance system entitled “Knowledge, Information, and Data Readiness Levels” (KaRLs), analogous to the NASA Technology Readiness Levels. The KaRL system assesses the type, extent, and usability of the available data, information, and knowledge and integrates the participation of relevant and interested stakeholders in a cocreation/codesign process to improve current risk assessment, communication, and governance. The novelty of the new system is to communicate and share all available and relevant elements on material related risks in a user/stakeholder-friendly, transparent, flexible, and holistic way and so stimulate reflection, awareness, communication, and a deeper understanding that ultimately enables the discursive process that is needed for the sustainable risk governance of new materials.
Since its isolation, graphene has received growing attention from academia and industry due to its unique properties. However, the “what is my material” barrier hinders further commercialization. X-ray photoelectron spectroscopy (XPS) is considered as a method of choice for the determination of the elemental and chemical composition. In this work the influence of the morphology of graphene particles on the XPS results is studied and investigated as a function of X-ray energy, using conventional XPS with Al K𝜶 radiation and hard X-ray photoemission spectroscopy (HAXPES) using Cr K𝜶 radiation. Thereby, the information depth is varied between 10 and 30 nm. For this purpose, two commercial powders containing graphene nanoplatelets with lateral dimensions of either ≈100 nm or in the micrometer range are compared. These larger ones exist as stack of graphene layers which is inspected with scanning electron microscopy. Both kinds of particles are then functionalized with either oxygen or fluorine. The size of the graphene particles is found to influence the degree of functionalization. Only the combination of XPS and HAXPES allows to detect the functionalization at the outermost surface of the particles or even of the stacks and to provide new insights into the functionalization process.
Elemental composition and thickness determination of thin films by electron probe microanalysis
(2023)
Electron probe microanalysis (EPMA) applies to solid samples of homogenous (bulk) chemical composition and can usually not be applied to structures which are inhomogeneous in the micrometer range such as thin film systems down to a few nm. However, in combination with the established thin film software Stratagem, the thickness as well as the elemental composition of thin films on a substrate can be determined. This has been recently successfully demonstrated for Fe-Ni on Si and Si-Ge on Al2O3 thin film systems. For both systems five samples of different elemental composition and a reference were produced and characterised by inductively coupled plasma mass spectrometry (ICP-MS), Rutherford backscattering (RBS), and transmission electron microscopy (TEM) as reference values. Last year, 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 reevaluated the data acquired for the Fe-Ni and Si-Ge systems using the BadgerFilm software package and compared the obtained elemental compositions and thickness values with the results of the Stratagem software and the reference methods. The conclusion is that the BadgerFilm software shows good agreement with the elemental composition and thickness calculated by Stratagem (mostly <2% for both composition and thickness) and with the reference values for two representative thin film systems (<1%–2% for composition and <10%–20% for thickness).
The study described in this paper was conducted in the framework of the European nPSize project (EMPIR program) with the main objective of proposing new reference certified nanomaterials for the market in order to improve the reliability and traceability of nanoparticle size measurements. For this purpose, bimodal populations as well as complexly shaped nanoparticles (bipyramids, cubes, and rods) were synthesized. An inter-laboratory comparison was organized for comparing the size measurements of the selected nanoparticle samples performed with electron microscopy (TEM, SEM, and TSEM), scanning probe microscopy (AFM), or small-angle X-ray scattering (SAXS). The results demonstrate good consistency of the measured size by the different techniques in cases where special care was taken for sample preparation, instrument calibration, and the clear definition of the measurand. For each characterization method, the calibration process is described and a semi-quantitative table grouping the main error sources is proposed for estimating the uncertainties associated with the measurements. Regarding microscopy-based techniques applied to complexly shaped nanoparticles, data dispersion can be observed when the size measurements are affected by the orientation of the nanoparticles on the substrate. For the most complex materials, hybrid approaches combining several complementary techniques were tested, with the outcome being that the reliability of the size results was improved.
Here, we elucidate nonclassical multistep crystallization pathways of transition metal phosphates from aqueous solutions. We followed precipitation processes of M-struvites, NH4MPO4·6H2O, and M-phosphate octahydrates, M3(PO4)2·8H2O, where M = Ni, Co, or NixCo1–x, by using in situ scattering and spectroscopy-based techniques, supported by elemental mass spectrometry analyses and advanced electron microscopy. Ni and Co phosphates crystallize via intermediate colloidal amorphous nanophases, which change their complex structures while agglomerating, condensing, and densifying throughout the extended reaction times. We reconstructed the three-dimensional morphology of these precursors by employing cryo-electron tomography (cryo-ET). We found that the complex interplay between metastable amorphous colloids and protocrystalline units determines the reaction pathways. Ultimately, the same crystalline structure, such as struvite, is formed. However, the multistep process stages vary in complexity and can last from a few minutes to several hours depending on the selected transition metal(s), their concentration, and the Ni/Co ratio.
Iron Oxide Nanocubes as a New Certified Reference Material for Nanoparticle Size Measurements
(2023)
The rational design and increasing industrial use of nanomaterials require a reliable characterization of their physicochemical key properties like size, size distribution, shape, and surface chemistry. This calls for nanoscale reference materials (nanoRMs) for the validation and standardization of commonly used characterization methods closely matching real-world nonspherical nano-objects. This encouraged us to develop a nonspherical nanoRM of very small size consisting of 8 nm iron oxide nanocubes (BAM-N012) to complement spherical gold, silica, and polymer nanoRMs. In the following, the development and production of this nanoRM are highlighted including the characterization by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) as complementary methods for size and shape parameters, homogeneity and stability studies, and calculation of a complete uncertainty budget of the size features. The determination of the nanocubes’ edge length by TEM and SAXS allows a method comparison. In addition, SAXS measurements can also provide the mean particle number density and the mass concentration. The certified size parameters, area equivalent circular diameter and square edge length, determined by TEM with a relative expanded uncertainty below 9%, are metrologically traceable to a natural constant for length, the very precisely known (111) lattice spacing of silicon. Cubic BAM-N012 qualifies as a certified nanoRM for estimating the precision and trueness, validation, and quality assurance of particle size and shape measurements with electron microscopy and SAXS as well as other sizing methods suitable for nanomaterials. The production of this new iron oxide nanocube RM presents an important achievement for the nanomaterial community, nanomaterial manufacturers, and regulators.
Electron microscopy (EM) is the gold standard for the characterisation of the morphology (size and shape) of nanoparticles. Visual observation of objects under examination is always a necessary first step in the characterisation process. Several questions arise when undertaking to identify and count particles to measure their size and shape distribution. In addition to challenges with the dispersion and identification of the particles, more than one protocol for counting particles is in use. This paper focuses on precise rules for the counting of particles in EM micrographs, as this influences the measurement accuracy of the number of particles, thus implicitly affecting the size values of the counted particles. We review and compare four different, commonly used methods for counting, which we then apply in case studies. The impact of the selected counting rule on the obtained final particle size distribution is highlighted. One main aim of this analysis is to support the application of a specific, well-defined counting approach in accordance with regulatory
requirements to contribute to achieving more reliable and reproducible results. It is also useful for the new harmonised measurement procedures for determining the particle size and particle size distribution of nanomaterials.
Catalysts are important components in chemical processes because they lower the activation energy and thus determine the rate, efficiency and selectivity of a chemical reaction. This property plays an important role in many of today’s processes, including the electrochemical splitting of water. Due to the continuous development of catalyst materials, they are becoming more complex, which makes a reliable evaluation of physicochemical properties challenging even for modern analytical measurement techniques and industrial manufacturing.
We present a fast, vacuum-free and non-destructive analytical approach using multi-sample spectroscopic ellipsometry to determine relevant material parameters such as film thickness, porosity and composition of mesoporous IrOx–TiOy films. Mesoporous IrOx–TiOy films were deposited on Si wafers by sol–gel synthesis, varying the composition of the mixed oxide films between 0 and 100 wt%Ir. The ellipsometric modeling is based on an anisotropic Bruggeman effective medium approximation (a-BEMA) to determine the film thickness and volume fraction of the material and pores. The volume fraction of the material was again modeled using a Bruggeman EMA to determine the chemical composition of the materials. The ellipsometric fitting results were compared with complementary methods, such as scanning electron microscopy (SEM), electron probe microanalysis (EPMA) as well as environmental ellipsometric porosimetry (EEP).
Whereas the characterization of nanomaterials using different analytical techniques is often highly automated and standardized, the sample preparation that precedes it causes a bottleneck in nanomaterial analysis as it is performed manually. Usually, this pretreatment depends on the skills and experience of the analysts. Furthermore, adequate reporting of the sample preparation is often missing. In this overview, some solutions for techniques widely used in nano-analytics to overcome this problem are discussed. Two examples of sample preparation optimization by au-tomation are presented, which demonstrate that this approach is leading to increased analytical confidence. Our first example is motivated by the need to exclude human bias and focuses on the development of automation in sample introduction. To this end, a robotic system has been de-veloped, which can prepare stable and homogeneous nanomaterial suspensions amenable to a variety of well-established analytical methods, such as dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), field-flow fractionation (FFF) or single-particle inductively coupled mass spectrometry (sp-ICP-MS). Our second example addresses biological samples, such as cells exposed to nanomaterials, which are still challenging for reliable analysis. An air–liquid interface has been developed for the exposure of biological samples to nanomaterial-containing aerosols. The system exposes transmission electron microscopy (TEM) grids under reproducible conditions, whilst also allowing characterization of aerosol composition with mass spectrometry. Such an approach enables correlative measurements combining biological with physicochemical analysis. These case studies demonstrate that standardization and automation of sample preparation setups, combined with appropriate measurement processes and data reduction are crucial steps towards more reliable and reproducible data.
The roughness as a property of core–shell (CS) microparticles plays a key role in their functionality. Quantitative evaluation of the roughness of CS microparticles is, however, a challenging task with approaches using electron microscopy images being scarce and showing pronounced differences in terms of methodology and results. This work presents a generalized method for the reliable roughness determination of nonplanar specimens such as CS particles from electron microscopic images, the method being robust and reproducible with a high accuracy. It involves a self-written software package (Python) that analyzes the recorded images, extracts corresponding data, and calculates the roughness based on the deviation of the identified contour. Images of single particles are taken by a dual mode scanning electron microscopy (SEM) setup which permits imaging of the same field-of-view of the sample with high resolution and surface sensitive in SE InLens mode as well as in transmission mode (TSEM). Herein, a new type of polystyrene core–iron oxide shell–silica shell particles is developed to serve as a set of lower micrometer-sized study objects with different surface roughness; the analysis of their images by the semiautomatic workflow is demonstrating that the particles’ profile roughness can be quantitatively obtained.
Luminescent semiconductor quantum dots (QDs) are frequently used in the life and material sciences as reporter for bioimaging studies and as active components in devices such as displays, light-emitting diodes, solar cells, and sensors. Increasing concerns regarding the use of toxic elements like cadmium and lead, and hazardous organic solvents during QD synthesis have meanwhile triggered the search for heavy-metal free QDs using green chemistry syntheses methods. Interesting candidates are ternary AgInS2 (AIS) QDs that exhibit broad photoluminescence (PL) bands, large effective Stokes shifts, high PL quantum yields (PL QYs), and long PL lifetimes, which are particularly beneficial for applications such as bioimaging, white light-emitting diodes, and solar concentrators. In addition, these nanomaterials can be prepared in high quality with a microwave-assisted (MW) synthesis in aqueous solution. The homogeneous heat diffusion and instant temperature rise of the MW synthesis enables a better control of QD nucleation and growth and thus increases the batch-to-batch reproducibility. In this study, we systematically explored the MW synthesis of AIS/ZnS QDs by varying parameters such as the order of reagent addition, precursor concentration, and type of stabilizing thiol ligand, and assessed their influence on the optical properties of the resulting AIS/ZnS QDs. Under optimized synthesis conditions, water-soluble AIS/ZnS QDs with a PL QY of 65% and excellent colloidal and long-term stability could be reproducible prepared.
Binary photoluminescent semiconductor nanocrystals (quantum dots, QDs) are one of the best studied fluorescent nanomaterials, and their unique optoelectronic properties paved the road to many applications in (bio)nanophotonics, optoelectronics, and photovoltaics. However, concerns related to their toxic constituents like cadmium or lead and the emerging interest in greener chemistry synthesis approaches hamper their future applicability. Interesting alternatives for some applications like biosensing or bioimaging are heavy-metal-free ternary QDs like AgInS2 (AIS), CuInS2 (CIS), and quaternary QDs such as AIS-ZnS (ZAIS). In this context, we explored the effect of ligand denticity on the organic-to-aqueous phase transfer of oleylamine-stabilized ZAIS QDs with the hydrophilic ligands mercaptopropionic acid (MPA), dihydrolipoic acid (DHLA), and 3-mercapto-2,2-bis(mercaptomethyl)propanoic acid (3MPA), bearing mono-, bi-, and trialkyl thiol groups. Spectroscopic studies of the resulting water-dispersible ZAIS QDs revealed a considerable influence of ligand denticity and ligand-to-QD ratio on the spectral position and width (FWHM; full width at half-maximum) of the photoluminescence (PL) bands, the PL quantum yields (PL QY), and the PL decay kinetics. Thiol capping and phase transfer resulted in a loss in PL by at least a factor of 2. The ligand-induced PL quenching observed particularly for ligands bearing two or three thiol groups was attributed to the facilitated formation of surface-bound disulfides. The best colloidal stability under high dilution conditions was observed for 3MPA.
In this paper, the accurate determination of the size and size distribution of bipyramidal anatase nanoparticles (NPs) after deposition as single particles on a silicon substrate by correlative Scanning Electron Microscopy (SEM) with Atomic Force Microscopy (AFM) analysis is described as a new measurement procedure for metrological purposes. The knowledge of the exact orientation of the NPs is a crucial step in extracting the real 3D dimensions of the particles. Two approaches are proposed to determine the geometrical orientation of individual nano‐bipyramides: (i) AFM profiling along the long bipyramid axis and (ii) stage tilting followed by SEM imaging. Furthermore, a recently developed method, Transmission Kikuchi Diffraction (TKD), which needs preparation of the crystalline NPs on electron‐transparent substrates such as TEM grids, has been tested with respect to its capability of identifying the geometrical orientation of the individual NPs. With the NPs prepared homogeneously on a TEM grid, the transmission mode in a SEM, i.e., STEM‐in‐SEM (or T‐SEM), can be also applied to extract accurate projection dimensions of the nanoparticles from the same sample area as that analysed by SEM, TKD and possibly AFM. Finally, Small Angle X‐ray Scattering (SAXS) can be used as an ensemble technique able to measure the NPs in liquid suspension and, with ab‐initio knowledge of the NP shape from the descriptive imaging techniques, to provide traceable NP size distribution and particle concentration.
Ellipsometry-based approach for the characterization of mesoporous thin films for H2 technologies
(2021)
Porous thin layer materials are gaining importance in different fields of technology and pose a challenge to the accurate determination of materials properties important for their function. In this work, we demonstrate a hybrid measurement technique using ellipsometry together with other independent methods for validation. Ellipsometry provides information about the porosity of different mesoporous films (PtRuNP/OMC = 45%; IrOx = 46%) as well as about the pore size (pore radius of ca. 5 nm for PtRuNP/OMC). In addition, the electronic structure of a material, such as intraband transitions of a mesoporous IrOx film, can be identified, which can be used to better understand the mechanisms of chemical processes. In addition, we show that ellipsometry can be used as a scalable imaging and visualization method for quality assurance in production. These require accurate and traceable measurements, with reference materials playing an important role that include porosity and other related properties. We show that our novel analytical methods are useful for improving analytical work in this entire field.