TY - CONF A1 - Radnik, Jörg A1 - Hodoroaba, Vasile-Dan T1 - Morpho-Chemical Characterisation of Me-TiO2 Nanoparticles for Enhanced Photocatalytical Activity N2 - 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. T2 - ECASIA 2022 CY - Limerick, Ireland DA - 29.05.2022 KW - Titania nanoparticles KW - Photocatalysis KW - Scanning electron microscopy KW - Energy dispersive X-ray spectroscopy PY - 2022 AN - OPUS4-54977 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mrkwitschka, Paul T1 - Standardized Chemical Characterisation of Graphene Oxide Flakes by X-Ray Photoelectron Spectroscopy and Energy-Dispersive X-Ray Spectroscopy N2 - Reliable quantification of the chemical composition of graphene-related 2D materials as powders and liquid suspensions is a challenging task. Analytical methods such as XPS, ICP-MS, TGA and FTIR are recommended to be used in ongoing projects at standardisation bodies. The specific parameters to be measured are also defined, e.g. the oxygen-to-carbon (O/C) concentration ratio, the trace metal impurities, or the functional groups present [1]. In this contribution, for the first time, the results of a systematic study on the capability of SEM/EDS to reliably quantify the O/C ratio in a well-defined and well-characterized graphene oxide material [2] are presented. It is expected that the quantitative EDS analysis of light elements emitting characteristic X-ray lines below 1 keV to be provided with significantly larger measurement uncertainties than the analysis of elements with an atomic number of 11 (Na) or above [3]. The robustness of the SEM/EDS results obtained at various measurement conditions (various excitation energies) is tested by comparing the results to the established XPS analysis [4], which has been carried out on the same samples. A crucial step in sample preparation from liquid suspension with graphene oxides flakes onto a substrate for analysis with both XPS and EDS. It is demonstrated that if a closed and enough thick drop-cast deposited spot is succeeded to be deposited on a substrate, both surface-sensitive XPS analysis and bulk-characterising EDS result in very similar elemental composition of oxygen and carbon. Hence, theoretical, expected O/C atomic ratio values for pure graphene oxide of ~0.5 [1] are achieved (with both methods), see Figure 1. Further, the effect of untight deposited material enabling co-analysis of the (silicon) substrate, is evaluated for both methods, XPS and EDS. To note that all the EDS results in this study have been quantified standardless. The results of this study demonstrate the reliability of the reference measurement protocol for SEM/EDS to be introduced into ISO/DTS 23359, including the dedicated sample preparation, particularly for the cases when the concentration of the GO flakes in stock liquid suspension is low. Further, also the consideration of this GO material as one of the very few available as a commercial material on the market as the very first GO reference material with regard to its morphology as well as chemical composition. Both the standard measurement procedure and the candidate reference material will immensely contribute to characterise reliably the chemical composition of graphene-related 2D materials with SEM/EDS as one of the most widely used methods in analytical laboratories T2 - EMAS 2025 Workshop CY - Mataró, Spain DA - 11.05.2025 KW - Advanced Materials KW - Graphene KW - Chemical Quantification KW - EDX KW - XPS PY - 2025 AN - OPUS4-64082 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pellegrino, F. A1 - Hodoroaba, Vasile-Dan A1 - Radnik, Jörg T1 - Unveiling Order in Graphene Oxide Synthesis Through A Design of Experiment and Chemometric Strategy Based on Tour’s Method N2 - Graphene oxide (GO), a derivative of graphene containing oxygen functional groups, shows significant potential for a wide range of applications due to its unique electrical, mechanical, and chemical properties. Traditional synthesis methods, such as Tour's method, often rely on trial-and-error, leading to variations in product quality and yield. To address these challenges, we applied Design of Experiments (DoE) to systematically investigate the effects of key synthesis parameters, including reaction temperature, reaction time, and oxidant concentration. We identified the most significant factors influencing GO characteristics using a Plackett-Burman design and chemometric analysis. Our results highlight that the oxidation level is the most critical factor, impacting outcomes observed through various characterization techniques, such as UV-Vis spectroscopy and X-Ray Diffraction. Principal Component Analysis (PCA) and Multiple Linear Regression (MLR) provided insights into the synthetic parameters most strongly affecting material properties. While some findings aligned with expectations, others were counterintuitive. For instance, oxidation temperature had a minimal effect on the final material characteristics and may not need to be prioritized in the synthesis process. On the other hand, stirring was found to enhance the homogeneity of the material and promote more uniform oxidation. This study demonstrates the effectiveness of DoE in the controlled production of graphene oxide, offering a reliable framework for manufacturing high-quality GO tailored to specific applications. By minimizing time and resource consumption, this approach is increasingly relevant in the context of materials science, which demands higher quality, safety and sustainability standards. T2 - Joint Regulatory Risk Assessors Summit – Advancing Safety & Sustainability Assessments of Advanced Materials CY - Paris, France DA - 19.06.2025 KW - Graphene oxide KW - Chemometry KW - UV-Vis KW - XRD KW - XPS KW - EDX PY - 2025 UR - https://macrame-project.eu/macrame-meetings-workshops/jointrras/#Agenda AN - OPUS4-63676 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Miliūtė, Aistė A1 - Bustamante, Joana A1 - Mieller, Björn A1 - Stawski, Tomasz A1 - George, Janine A1 - Knoop, F. T1 - High-quality zirconium vanadate samples for negative thermal expansion (NTE) analysis N2 - Zirconium vanadate (ZrV2O7) is a well-known negative thermal expansion (NTE) material which exhibits significant isotropic contraction over a broad temperature range (~150°C < T < 800°C). The linear thermal expansion coefficient of ZrV2O7 is −7.1×10-6 K-1. Therefore, it can be used to create composites with controllable expansion coefficients and prevent destruction by thermal shock. Material characterization, leading to application, requires pure, homogenous samples of high crystallinity via a reliable synthesis route. While there is a selection of described syntheses in the literature, it still needs to be addressed which synthesis route leads to truly pure and homogenous samples. Here, we study the influence of the synthesis methods (solid-state, sol-gel, solvothermal) and their parameters on the sample's purity, crystallinity, and homogeneity. The reproducibility of results and data obtained with scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry, and thermogravimetric analysis (DSC/TGA) were analyzed extensively. The sol-gel method proves superior to the solid-state method and produces higher-quality samples over varying parameters. Sample purity also plays an important role in NTE micro and macro-scale characterizations that explain the impact of porosity versus structural changes. Moreover, we implement ab-initio-based vibrational computations with partially treated anharmonicity (quasi-harmonic approximation, temperature-dependent effective harmonic potentials) in combination with experimental methods to follow and rationalize the negative thermal expansion in this material, including the influence of the local structure disorder, microstructure, and defects. Khosrovani et al. and Korthuis et al., in a series of diffraction experiments, attributed the thermal contraction of ZrV2O7 to the transverse thermal motion of oxygen atoms in V-O-V linkages. In addition to previous explanations, we hypothesize that local disorder develops in ZrV2O7 crystals during heating. We are working on the experimental ZrV2O7 development and discuss difficulties one might face in the process as well as high-quality sample significance in further investigation. The obtained samples are currently used in the ongoing research of structure analysis and the negative thermal expansion mechanism. T2 - TDEP2023: Finite-temperature and anharmonic response properties of solids in theory and practice CY - Linköping, Sweden DA - 21.08.2023 KW - NTE KW - Sol-gel KW - Solid-state KW - Ab-initio KW - TDEP PY - 2023 AN - OPUS4-58135 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Miliūtė, Aistė A1 - Bustamante, Joana A1 - Mieller, Björn A1 - Stawski, Tomasz A1 - George, Janine A1 - Knoop, F. T1 - High-quality zirconium vanadate samples for negative thermal expansion (NTE) analysis N2 - Zirconium vanadate (ZrV2O7) is a well-known negative thermal expansion (NTE) material which exhibits significant isotropic contraction over a broad temperature range (~150°C < T < 800°C). The linear thermal expansion coefficient of ZrV2O7 is −7.1×10-6 K-. Therefore, it can be used to create composites with controllable expansion coefficients and prevent destruction by thermal shock. Material characterization, leading to application, requires pure, homogenous samples of high crystallinity via a reliable synthesis route. While there is a selection of described syntheses in the literature, it still needs to be addressed which synthesis route leads to truly pure and homogenous samples. Here, we study the influence of the synthesis methods (solid-state, sol-gel, solvothermal) and their parameters on the sample's purity, crystallinity, and homogeneity. The reproducibility of results and data obtained with scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry, and thermogravimetric analysis (DSC/TGA) were analyzed extensively. The sol-gel method proves superior to the solid-state method and produces higher-quality samples over varying parameters. Sample purity also plays an important role in NTE micro and macro-scale characterizations that explain the impact of porosity versus structural changes. Moreover, we implement ab-initio-based vibrational computations with partially treated anharmonicity (quasi-harmonic approximation, temperature-dependent effective harmonic potentials) in combination with experimental methods to follow and rationalize the negative thermal expansion in this material, including the influence of the local structure disorder, microstructure, and defects. Khosrovani et al. and Korthuis et al., in a series of diffraction experiments, attributed the thermal contraction of ZrV2O7 to the transverse thermal motion of oxygen atoms in V-O-V linkages. In addition to previous explanations, we hypothesize that local disorder develops in ZrV2O7 crystals during heating. We are working on the experimental ZrV2O7 development and discuss difficulties one might face in the process as well as high-quality sample significance in further investigation. The obtained samples are currently used in the ongoing research of structure analysis and the negative thermal expansion mechanism. T2 - 4th International Symposium on Negative Thermal Expansion and Related Materials (ISNTE-4) CY - Padua, Italy DA - 04.07.2023 KW - NTE KW - Sol-gel KW - Solid-state KW - Ab-initio KW - TDEP PY - 2023 AN - OPUS4-58132 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Miliūtė, Aistė A1 - Bustamante, Joana A1 - Mieller, Björn A1 - Stawski, Tomasz A1 - George, Janine A1 - Knoop, F. T1 - High-quality zirconium vanadate samples for negative thermal expansion (NTE) analysis N2 - Zirconium vanadate (ZrV2O7) is a well-known negative thermal expansion (NTE) material which exhibits significant isotropic contraction over a broad temperature range (~150°C < T < 800°C). The linear thermal expansion coefficient of ZrV2O7 is −7.1×10-6 K-. Therefore, it can be used to create composites with controllable expansion coefficients and prevent destruction by thermal shock. Material characterization, leading to application, requires pure, homogenous samples of high crystallinity via a reliable synthesis route. While there is a selection of described syntheses in the literature, it still needs to be addressed which synthesis route leads to truly pure and homogenous samples. Here, we study the influence of the synthesis methods (solid-state, sol-gel, solvothermal) and their parameters on the sample's purity, crystallinity, and homogeneity. The reproducibility of results and data obtained with scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry, and thermogravimetric analysis (DSC/TGA) were analyzed extensively. The sol-gel method proves superior to the solid-state method and produces higher-quality samples over varying parameters. Sample purity also plays an important role in NTE micro and macro-scale characterizations that explain the impact of porosity versus structural changes. Moreover, we implement ab-initio-based vibrational computations with partially treated anharmonicity (quasi-harmonic approximation, temperature-dependent effective harmonic potentials) in combination with experimental methods to follow and rationalize the negative thermal expansion in this material, including the influence of the local structure disorder, microstructure, and defects. Khosrovani et al. and Korthuis et al., in a series of diffraction experiments, attributed the thermal contraction of ZrV2O7 to the transverse thermal motion of oxygen atoms in V-O-V linkages. In addition to previous explanations, we hypothesize that local disorder develops in ZrV2O7 crystals during heating. We are working on the experimental ZrV2O7 development and discuss difficulties one might face in the process as well as high-quality sample significance in further investigation. The obtained samples are currently used in the ongoing research of structure analysis and the negative thermal expansion mechanism. T2 - 16th International conference on materials chemistry (MC16) CY - Dublin, Ireland DA - 03.07.2023 KW - NTE KW - Sol-gel KW - Solid-state KW - Ab-initio KW - TDEP PY - 2023 AN - OPUS4-58134 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yu, C.-H. T1 - Distribution of subsurface residual stress as a function of wall thickness in stainless steel 316L LPBF structures N2 - The subsurface residual stress in laser powder bed fused 316L structures was analyzed using X-ray diffraction (XRD) and layer removal. The influence of varying structure thicknesses was investigated. In this study the importance of combining surface roughness measurements with XRD was shown. Moreover, a clear relation between the structure thickness and the subsurface residual stress profiles was observed. T2 - The 11th International Conference on Residual Stress CY - Nancy, Frankreich DA - 28.03.2022 KW - AGIL KW - Residual Stress KW - X-ray Diffraction KW - Additive Manufacturing PY - 2022 AN - OPUS4-54581 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Serrano-Munoz, Itziar T1 - Residual stress analysis in selective laser melted parts of superalloy IN718 N2 - Additive Manufacturing by Selective Laser Melting (SLM) offers an ample scope for producing geometrically complex parts as compared to the traditional subtractive manufacturing strategies. However, the residual stresses (RS) developed during the processing can reduce the load bearing capacity as well as induce unwanted distortion, limiting the life time and the application of SLM parts. T2 - BESSY II User meeting CY - BESSY II Photon Source, Adlershof Berlin, Germany DA - 06.12.2018 KW - Laser Beam Melting KW - AM IN718 KW - Residual stress measurements PY - 2018 AN - OPUS4-47179 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Serrano-Munoz, Itziar T1 - Synchrotron X-Ray Refraction detects microstructure and porosity evolution during in-situ heat treatments N2 - The complexity of any microstructural characterization significantly increases when there is a need to evaluate the microstructural evolution as a function of temperature. To date, this characterization is primarily performed by undertaking elaborative ex-situ experiments where the material’s heating procedure is interrupted at different temperatures or times. Moreover, these studies are often limited to a region smaller than the representative elementary volume, which can lead to partial or even biased interpretations of the collected data. This limitation can be greatly overcome by using in-situ synchrotron X-ray refraction (SXRR). In this study, SXRR has been combined with in-situ heat treatment to monitor the porosity evolution as a function of temperature. It is shown that SXRR is a robust and straightforward method for time-resolved (3-5 min required per scan) evaluation of thermally induced microstructural changes over macroscopically relevant volumes. T2 - SNI2022, German conference for research with synchrotron radiation, neutrons and ion beams at large facilities CY - Berlin, Germany DA - 05.09.2022 KW - Synchrotron X-Ray Refraction KW - In situ heating KW - AlSi10Mg KW - Laser powder bed fusion KW - Thermally induced porosity PY - 2022 AN - OPUS4-55778 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hodoroaba, Vasile-Dan A1 - Terborg, R. A1 - Boehm, S. T1 - Analysis of elemental composition of Fe1-xNix and Si1-xGex alloy thin films by EPMA and µ-XRF N2 - 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. T2 - Microscopy & Microanalysis 2019 CY - Portland, OR, USA DA - 03.08.2019 KW - Thin films KW - EPMA KW - µ-XRF KW - Elemental composition KW - Atomic fraction KW - Fe-Ni KW - Si-Ge PY - 2019 AN - OPUS4-48709 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -