TY - JOUR A1 - Roy, Arkendu A1 - Kumar, Sourabh A1 - de Oliveira Guilherme Buzanich, Ana A1 - Prinz, Carsten A1 - Götz, Emilia A1 - Retzmann, Anika A1 - Hickel, Tilmann A1 - Bhattacharya, Biswajit A1 - Emmerling, Franziska T1 - Synergistic Catalytic Sites in High‐Entropy Metal Hydroxide Organic Framework for Oxygen Evolution Reaction N2 - AbstractThe integration of multiple elements in a high‐entropy state is crucial in the design of high‐performance, durable electrocatalysts. High‐entropy metal hydroxide organic frameworks (HE‐MHOFs) are synthesized under mild solvothermal conditions. This novel crystalline metal–organic framework (MOF) features a random, homogeneous distribution of cations within high‐entropy hydroxide layers. HE‐MHOF exhibits excellent electrocatalytic performance for the oxygen evolution reaction (OER), reaching a current density of 100 mA cm−2 at ≈1.64 VRHE, and demonstrates remarkable durability, maintaining a current density of 10 mA cm−2 for over 100 h. Notably, HE‐MHOF outperforms precious metal‐based electrocatalysts despite containing only ≈60% OER active metals. Ab initio calculations and operando X‐ray absorption spectroscopy (XAS) demonstrate that the high‐entropy catalyst contains active sites that facilitate a multifaceted OER mechanism. This study highlights the benefits of high‐entropy MOFs in developing noble metal‐free electrocatalysts, reducing reliance on precious metals, lowering metal loading (especially for Ni, Co, and Mn), and ultimately reducing costs for sustainable water electrolysis technologies. KW - Electrocatalysis KW - Green Hydrogen PY - 2024 DO - https://doi.org/10.1002/adma.202408114 SP - 1 EP - 14 PB - Wiley AN - OPUS4-61739 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hickel, Tilmann T1 - Solute induced defect phase transformations in Mg alloys N2 - The study of defect phases is important for designing nanostructured metals and alloys. Grain boundaries (GBs) form one class of defects that directly influence materials properties, such as deformability and strength. At the same time, alloying can introduce GB phase transformations and can therewith alter mechanical performance. In this work, we will discuss the concept of GB phase diagrams for several examples. The focus will be on the defect phases of a Σ7 (12¯30) [0001] 21.78◦ symmetric tilt GB in hcp Mg. Ab-initio simulations as a function of stress and temperature (using quasi-harmonic approximation) are performed, and different types of phase transformations are revealed. To this end, the influence of the chemical degree of freedom on the defect phases is studied for the example of Ga addition, using an efficient screening approach that combines empirical potentials and accurate ab-initio calculations. By exploiting the concept of defect phase diagrams, a phase transformation from the T to the A structural type and as well as a systematic transition of the segregation site preference is revealed. The results qualitatively agree well with experimental observations from scanning transition electron microscopy. The underlying physical mechanisms have an impact on grain-boundary engineering in metallic alloys. T2 - Calphad 2024 Conference CY - Karlsruhe, Germany DA - 26.05.2024 KW - Ab initio simulations KW - Grain boundaries KW - Defect phase diagram KW - Segregation PY - 2024 AN - OPUS4-62719 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hickel, Tilmann T1 - Research data infrastructures as enablers for materials design N2 - Suitable material solutions are of key importance in designing and producing components for engineering systems – either for functional or structural applications. Materials data are generated, transferred, and introduced at each step along the complete life cycle of a component. A reliable materials data space is therefore crucial in the digital transformation and an important prerequisite for machine learning in materials science. Therefore, the consortium NFDI MatWerk aims to develop a sustainable infrastructure for the standardized digital representation of materials science and engineering (MatWerk). The goal is to seamlessly integrate decentralized data and metadata, experimental and computational workflows, and a materials ontology to maximize interoperability and reproducibility of materials data processing. To this end, data use profiles of participant projects from different sub-disciplines are analyzed to identify the most relevant scientific scenarios within MatWerk. Similarly, the Plattform MaterialDigital (PMD) is committed to provide a prototypical infrastructure for the digitalization of materials in an industrial context implemented by decentralized data servers, semantic data schemas and digital workflows. The standards, methods, and tools developed within the PMD are deployed and consolidated within the context of currently more than 20 BMBF-funded academic and industrial research consortia. Scientific workflow environments represent a major focus area, including efforts to improve the definition and representation of digital workflows, as well as their distribution in form of a workflow store. In this presentation we will describe the overarching visions behind these initiatives, their status, and progress of dissemination with a focus on the workflow activities and the connection between theoretical predictions and experimental solutions. Following the philosophy of both consortia, specific examples will be used to demonstrate innovative and pragmatic solutions. T2 - FLAIR Colloquium CY - Darmstadt, Germany DA - 10.06.2024 KW - MaterialDigital KW - NFDI-MatWerk KW - Workflows KW - Defect phase diagrams PY - 2024 AN - OPUS4-62720 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hickel, Tilmann A1 - Richter, Silke A1 - Bitzek, E. A1 - Ávila Calderón, Luis A1 - Gedsun, A. A1 - Forti, M. A1 - Hammerschmidt, T. A1 - Olbricht, Jürgen A1 - Skrotzki, Birgit T1 - NFDI-MatWerk/IUC02 Definition for Reference Data of Materials N2 - This definition was agreed within the infrastructure use case IUC02 “Framework for curation and distribution of reference datasets” of the consortium NFDI-MatWerk. It is broadly formulated to cover experimental and simulation MSE data and will be developed further in agreement with the MSE community. KW - Referenzdaten KW - Digitalisierung KW - NFDI-MatWerk KW - Research Data Management KW - Reference Data PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-611688 DO - https://doi.org/10.5281/zenodo.11667673 PB - Zenodo CY - Geneva AN - OPUS4-61168 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tehranchi, Ali A1 - Zhang, S. A1 - Zendegani, A. A1 - Hickel, Tilmann A1 - Neugebauer, J. A1 - Scheu, C. T1 - Metastable defect phase diagrams as roadmap to tailor chemically driven defect formation N2 - Thermodynamic bulk phase diagrams have become the roadmap used by researchers to identify alloy compositions and process conditions that result in novel materials with tailored properties. Recent experimental studies show that changes in the alloy composition can drive not only transitions in the bulk phases present in a material, but also in the concentration and type of defects they contain. Defect phase diagrams in combination with density functional theory provide a natural route to study these chemically driven defects. Our results reveal, however, that direct application of equilibrium bulk thermodynamics can fail to reproduce experimentally observed defect formation. Therefore, we extend the concept to metastable defect phase diagrams to account for kinetic limitations that prevent the system from reaching equilibrium. We apply this concept to successfully explain the formation of large concentrations of planar defects in supersaturated Fe-Nb solid solutions. We then utilize it to design suitable conditions for synthesis, which we subsequently realized experimentally, successfully validating the formation of the predicted defects in Mg-Al-Ca alloys. The concept offers new avenues for the design of materials performance by tailoring defect structures. KW - Metastable defect phase diagram KW - Ab initio thermodynamics KW - Chemical potential KW - Laves phases KW - Transmission electron microscopy PY - 2024 DO - https://doi.org/10.1016/j.actamat.2024.120145 SN - 1359-6454 VL - 277 SP - 1 EP - 9 PB - Elsevier Ltd. AN - OPUS4-61803 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhu, L. A1 - Srinivasan, P. A1 - Gong, Y. A1 - Hickel, Tilmann A1 - Grabowski, B. A1 - Körmann, Fritz A1 - Neugebauer, J. T1 - Melting properties of the refractory metals V and W and the binary VW alloy fully from first principles N2 - We investigate the melting properties of the bcc refractory metals V and W, and the disordered equiatomic VW alloy from first principles. We show that thermal vibrations have a large impact on the electronic density of states (DOS) and thus considerably affect the electronic contribution to the free energy. For W, the impact of vibrations on the electronic free energy of solid and liquid is different. This difference substantially impacts the computed melting point and also triggers a large electronic heat capacity difference between solid and liquid. For V, although vibrations likewise affect the electronic free energy, the effect on the melting properties cancels out to a large degree. For the binary VW alloy we observe a similar impact as for W, but slightly weaker. The underlying physics is explained in terms of the electronic DOS of the solid and liquid phases. Based on our accurate first-principles results, we reveal critical limitations of the Sommerfeld approximation in predicting the electronic heat KW - Crystal melting KW - Thermodynamics KW - Metals KW - Ab initio molecular dynamics KW - Density functional theory PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618100 DO - https://doi.org/10.1103/PhysRevB.109.094110 SN - 2469-9950 VL - 109 IS - 9 SP - 1 EP - 18 PB - American Physical Society (APS) AN - OPUS4-61810 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhou, X. A1 - Mathews, P. A1 - Berkels, B. A1 - Delis, W. A1 - Saood, S. A1 - Alhassan, A. A1 - Keuter, P. A1 - Schneider, J. A1 - Korte-Kerzel, S. A1 - Sandlöbes, S. A1 - Raabe, D. A1 - Neugebauer, j. A1 - Dehm, G. A1 - Hickel, Tilmann A1 - Scheu, C. A1 - Zhang, S. T1 - Materials Design by Constructing Phase Diagrams for Defects N2 - Phase transformations and crystallographic defects are two essential tools todrive innovations in materials. Bulk materials design via tuning chemicalcompositions is systematized using phase diagrams. It is shown here that thesame thermodynamic concept can be applied to manipulate the chemistry atdefects. Grain boundaries in Mg–Ga system are chosen as a model system,because Ga segregates to the boundaries, while simultaneously improving thestrength and ductility of Mg alloys. To reveal the role of grain boundaries,correlated atomic-scale characterization and simulation to scope and buildphase diagrams for defects are presented. The discovery is enabled bytriggering phase transformations of individual grain boundaries through localalloying, and sequentially imaging the structural and chemical changes usingatomic-resolution scanning transmission electron microscopy. Ab initiosimulations determined the thermodynamic stability of grain boundaryphases, and found out that increasing Ga content enhances grain boundarycohesion, relating to improved ductility. The methodology to trigger, trace,and simulate defect transformation at atomic resolution enables a systematicdevelopment of defect phase diagrams, providing a valuable tool to utilizechemical complexity and phase transformations at defects. KW - Automatic pattern recognition KW - Defect phase diagram KW - Density functional theory KW - Grain boundary complexion KW - Transmission electron microscopy PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618063 DO - https://doi.org/10.1002/adma.202402191 SN - 1521-4095 SP - 1 EP - 9 PB - Wiley AN - OPUS4-61806 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hickel, Tilmann T1 - Hydrogen redistribution during electrochemical charging and mechanical testing: insights from a combined ab initio and finite element method N2 - In advanced high strength steels the mechanisms of hydrogen embrittlement are expected to be strongly connected to the amount of retained austenite (RA) contained in the microstructure and its transformation upon deformation. We have developed a multi-scale model for the hydrogen redistribution during hydrogen charging and tensile loading within martensitic/austenitic microstructure. Ab initio simulations have been used to resolve the complex energy profile of hydrogen in the martensite/austenite interface. Representative microstructures with different amounts of RA have been converted form experimental SEM-EBSD measurements. Simulations with the finite element method (FEM) have been used to analyse H concentration profiles within the microstructure. The simulations confirm an accumulation of H within the austenitic phase during charging, which undergoes a phase transformation under applied mechanical load during tensile testing and releases accumulated H into the martensite matrix. As a result, there is a pronounced H segregation to the microstructure regions subjected to high hydrostatic tensile stresses and plastic strains, which has a strong impact on the embrittlement behaviour. T2 - DPG Frühjahrstagung Sektion SKM CY - Berlin, Germany DA - 17.03.2024 KW - Hydrogen KW - Steel KW - Structural transformation KW - Ab initio simulation KW - Multiscale simulation PY - 2024 AN - OPUS4-62726 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Darvishi Kamachali, Reza A1 - Wallis, Theophilus A1 - Ikeda, Yuki A1 - Saikia, U. A1 - Ahmadian, A. A1 - Liebscher, C. A1 - Hickel, Tilmann A1 - Maaß, Robert T1 - Giant segregation transition as origin of liquid metal embrittlement in the Fe-Zn system N2 - A giant Zn segregation transition is revealed using CALPHAD-integrated density-based modeling of segregation into Fe grain boundaries (GBs). The results show that above a threshold of only a few atomic percent Zn in the alloy, a substantial amount of up to 60 at.% Zn can segregate to the GB. We found that the amount of segregation abruptly increases with decreasing temperature, while the Zn content in the alloy required for triggering the segregation transition decreases. Direct evidence of the Zn segregation transition is obtained using high-resolution scanning transmission electron microscopy. Base on the model, we trace the origin of the segregation transition back to the low cohesive energy of Zn and a miscibility gap in Fe-Zn GB, arising from the magnetic ordering effect, which is confirmed by ab-initio calculations. We also show that the massive Zn segregation resulting from the segregation transition greatly assists with liquid wetting and reduces the work of separation along the GB. The current predictions suggest that control over Zn segregation, by both alloy design and optimizing the galvanization and welding processes, may offer preventive strategies against liquid metal embrittlement. KW - CALPHAD KW - Microstructure Design KW - Grain boundary engineering KW - Steels KW - Density-based Model KW - Segregation Engineering PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-584292 DO - https://doi.org/10.1016/j.scriptamat.2023.115758 SN - 1359-6462 SN - 1872-8456 VL - 238 SP - 1 EP - 5 PB - Elsevier CY - Amsterdam AN - OPUS4-58429 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hickel, Tilmann T1 - Fundamental insights into the mechanism of hydrogen embrittlement N2 - The talks starts with a study on H trapping and embrittlement in high-strength Al alloys. Then the phase stability and transformation between different Fe-H phases is discussed, together with implications on crack nucleation. In the last part MD-MC simulation of hydride formation at crack tips in Al alloys are shown. T2 - Integrated Computational Materials, Process and Product Engineering Conference, IC-MPPE CY - Leoben, Austria DA - 06.06.2024 KW - Hydrogen KW - Ab initio thermodynamics KW - Multiscale simulation KW - Hydride formation KW - Cracks PY - 2024 AN - OPUS4-62727 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ávila Calderón, Luis T1 - Framework for Curation and Distribution of Reference Datasets on the Example of Creep Data of Ni- Based Superalloys N2 - This presentation introduces our current effort to develop a best practice framework for generating and distributing MSE reference datasets using creep data of Ni-based superalloys as an example, building on previous approaches. Such reference datasets can be used in the verification of testing equipment or to compare experimental or simulation results among different laboratories or collaborative centers. Our framework concept, for reference data, includes the generation of the data along with an agreement on the necessary metadata, considering the intended usage, and the integration into an easily accessible digital infrastructure to annotate and discover/distribute the datasets using a metadata schema accordingly aligned to a domain ontology. T2 - International Materials Science and Engineering Congress - MSE 2024 CY - Darmstadt, Germany DA - 24.09.2024 KW - Referenzdaten KW - Digitalisierung KW - Data schema KW - NFDI-MatWerk KW - Datenschema KW - FAIR PY - 2024 AN - OPUS4-61175 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chakraborty, P. A1 - Mouton, I. A1 - Gault, B. A1 - Tehranchi, Ali A1 - Neugebauer, J. A1 - Hickel, Tilmann T1 - Effect of Sn on stacking fault energies in zirconium and its hydrides N2 - Hydrogen embrittlement in Zr-alloy fuel cladding is a primary safety concern for water-based nuclear reactors. Here we investigated the stabilization of planar defects within the forming hydrides by Sn, the primary alloying element of Zircaloy-4 used in the cladding. In order to explain the formation of hydrides and planar defects observed in our experiments, we performed atomic-scale ab initio calculations focusing on the solute interactions with generalized stacking faults in hcp 𝛼-Zr and fcc zirconium hydrides. Our calculations showed that an increase in Sn concentration leads to a stabilization of stacking faults in both the 𝛼-Zr and hydride phases. However, the solution enthalpy of Sn is lower in the 𝛼-Zr as compared to the other hydride phases, indicative of two competing processes of Sn depletion/enrichment at the Zr hydride/matrix interface. This is corroborated by experimental findings, where Sn is less soluble in hydrides and is mostly found trapped at interfaces and planar defects, indicative of stacking faults inside the hydride phases. Our systematic investigation enables us to understand the presence and distribution of solutes in the hydride phases, which provides a deeper insight into the microstructural evolution of such alloy's properties during its service lifetime. KW - Defects KW - First-principles calculations KW - Interface and surface thermodynamics KW - Microstructure KW - Hydrides KW - Structural properties PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618044 DO - https://doi.org/10.1103/PhysRevMaterials.8.033605 SN - 2475-9953 VL - 8 IS - 3 SP - 1 EP - 9 PB - APS AN - OPUS4-61804 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hickel, Tilmann T1 - Effect of Hydrogen on the Phase Stability of Steels N2 - In this work, we studied the role of extreme hydrogen concentrations on the relative stability of the fcc/bcc/hcp phases using the ab initio thermodynamics. The results indicate that at low hydrogen chemical potentials the stability of the fcc phase, which can be representative of retained austenite (RA) in steels, is slightly enhanced by the presence of H atoms. In contrast, at high hydrogen chemical potentials the bcc phase is stabilized by H. Moreover, since the excess volume of the hydrogen-rich bcc phase is significantly larger than that of the fcc phase, the presence of a stress field can change the relative stability of these phases in the coexistence regions of the phase diagram. This feature is particularly important for cyclic loading conditions: during loading cycles forward and reverse phase transformations occur and the H released by these transformations can damage the material. T2 - TMS Annual Meeting 2024 CY - Orlando, FL, USA DA - 03.03.2024 KW - Hydrogen KW - Ab initio thermodynamics KW - Multiscale simulation KW - Hydride formation KW - Workflow PY - 2024 AN - OPUS4-62730 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Esakkiraja, N. A1 - Vishwakarma, A. A1 - Makineni, S. K. A1 - Jayaram, V. A1 - Hickel, Tilmann A1 - Divinski, S. V. A1 - Paul, A. T1 - Diffusion-controlled growth and microstructural evolution between Pt and Pd containing B2-NiAl bondcoats and Ni-based single crystal superalloy N2 - Pt-modified NiAl bond coats are used to extend the lifetime of blades in gas turbine engine applications. However, they suffer from the growth of deleterious precipitates within the interdiffusion zone. Partial substitution of Pt by Pd is advantageous in reducing the interdiffusion zone thickness between the bond coat and the superalloy, providing comparable oxidation properties, and critically reducing the propensity to form brittle (Pt,Ni)Al2 precipitates. In this study, we utilize the pseudo-binary diffusion couple method to estimate the interdiffusion coefficients of Ni and Al in Pd, Pd-Pt and Pt-modified nickel aluminides. Additionally, the main and cross-interdiffusion coefficients are estimated in the ternary diffusion couples. The estimated diffusion coefficients in the 𝛽-NiAl phase reflect on the thickness of the 𝛽 phase in the superalloy bond coat interdiffusion zone. Pd reduces the pseudo-binary interdiffusion coefficients of Ni–Al and also decreases the main and cross-ternary interdiffusion coefficients. This correlates with the reduction of the interdiffusion zone thickness by Pd. The diffusion process is strongly assisted by point defects in this phase. Ab initio-informed defect calculations are done to explain diffusion retardation in the presence of Pd (compared to Pt) with decreased defect concentrations. Furthermore, through in-depth microstructure characterization performed by electron probe micro analyser, transmission electron microscopy, and atom probe tomography, the presence of 𝜎, 𝑅 and 𝜇 phases as TCP precipitates in the interdiffusion zone are identified. The results give insights into the coatings’ diffusional properties that influence the service life of the product. KW - Interdiffusion KW - Bondcoat KW - Topologically close pack (TCP) phase KW - Transmission electron microscopy KW - Atom probe tomography PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618091 DO - https://doi.org/10.1016/j.actamat.2024.119687 SN - 1359-6454 VL - 266 SP - 1 EP - 14 PB - Elsevier CY - Amsterdam AN - OPUS4-61809 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hickel, Tilmann T1 - Data driven research on hydrogen in metals N2 - The talk gives an overview on data-driven research on hydrogen in metals performed at BAM. The focus is on a ab-initio based high-throughput study on the hydrogen solubility in metals and metallic alloys. Furthermore, the redistribution of hydrogen in transforming microstructures is addressed. The talk ends with an explanation of participant projects in NFDI-MatWerk, motivating the formation of a new project connected to hydrogen technology. T2 - DGM Fachausschuss “Wasserstoffeffekte in Werkstoffen" CY - Saarbrücken, Germany DA - 05.05.2024 KW - Hydrogen KW - Solubility KW - High-throughput study KW - Ab initio simulation KW - NFDI-MatWerk PY - 2024 AN - OPUS4-62721 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hickel, Tilmann T1 - Constructing defect phase diagrams from ab initio calculations N2 - Thermodynamic bulk phase diagrams have become the roadmap used by researchers to identify alloy compositions and process conditions that result in novel materials with tailored microstructures. On the other hand, recent progress in experimental atomic-scale characterization techniques allows one to study the local chemical composition at individual defects such as interfaces, grain boundaries, dislocations and surfaces. They show that changes in the alloy composition can drive not only transitions in the bulk phases present in a material, but also in the concentration and type of defects they contain. Defect phase diagrams, using chemical potentials as thermodynamics variables, provide a natural route to study these chemically driven defects. Our results show, however, that the direct application of thermodynamic approaches can fail to reproduce the experimentally observed defect formation. Therefore, we extend the concept to metastable defect phase diagrams to account for kinetic limitations that prevent the system from reaching equilibrium. We use ab initio calculations based on density functional theory to quantify the extension of regions where defect formation is expected. We successfully applied this concept to explain the formation of large concentrations of planar defects in supersaturated Fe2Nb Laves phases. In addition, we identify in a joint study with experiments conditions and structures in Mg-Al-Ca alloys for defect phase occurrence. The concept offers new avenues for designing materials with tailored defect structures. T2 - Materials Science Colloquium CY - Uppsala, Sweden DA - 25.04.2024 KW - Ab initio simulations KW - Grain boundaries KW - Defect phase diagram KW - Laves phases KW - Workflow PY - 2024 AN - OPUS4-62731 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bayerlein, Bernd A1 - Waitelonis, Jörg A1 - Birkholz, Henk A1 - Jung, Matthias A1 - Schilling, Markus A1 - v. Hartrott, Philipp A1 - Bruns, Marian A1 - Schaarschmidt, Jörg A1 - Beilke, Kristian A1 - Mutz, Marcel A1 - Nebel, Vincent A1 - Königer, Veit A1 - Beran, Lisa A1 - Kraus, Tobias A1 - Vyas, Akhilesh A1 - Vogt, Lars A1 - Blum, Moritz A1 - Ell, Basil A1 - Chen, Ya‐Fan A1 - Waurischk, Tina A1 - Thomas, Akhil A1 - Durmaz, Ali Riza A1 - Ben Hassine, Sahar A1 - Fresemann, Carina A1 - Dziwis, Gordian A1 - Beygi Nasrabadi, Hossein A1 - Hanke, Thomas A1 - Telong, Melissa A1 - Pirskawetz, Stephan A1 - Kamal, Mohamed A1 - Bjarsch, Thomas A1 - Pähler, Ursula A1 - Hofmann, Peter A1 - Leemhuis, Mena A1 - Özçep, Özgür L. A1 - Meyer, Lars‐Peter A1 - Skrotzki, Birgit A1 - Neugebauer, Jörg A1 - Wenzel, Wolfgang A1 - Sack, Harald A1 - Eberl, Chris A1 - Portella, Pedro Dolabella A1 - Hickel, Tilmann A1 - Mädler, Lutz A1 - Gumbsch, Peter T1 - Concepts for a Semantically Accessible Materials Data Space: Overview over Specific Implementations in Materials Science N2 - This article describes advancements in the ongoing digital transformation in materials science and engineering. It is driven by domain‐specific successes and the development of specialized digital data spaces. There is an evident and increasing need for standardization across various subdomains to support science data exchange across entities. The MaterialDigital Initiative, funded by the German Federal Ministry of Education and Research, takes on a key role in this context, fostering collaborative efforts to establish a unified materials data space. The implementation of digital workflows and Semantic Web technologies, such as ontologies and knowledge graphs, facilitates the semantic integration of heterogeneous data and tools at multiple scales. Central to this effort is the prototyping of a knowledge graph that employs application ontologies tailored to specific data domains, thereby enhancing semantic interoperability. The collaborative approach of the Initiative's community provides significant support infrastructure for understanding and implementing standardized data structures, enhancing the efficiency of data‐driven processes in materials development and discovery. Insights and methodologies developed via the MaterialDigital Initiative emphasize the transformative potential of ontology‐based approaches in materials science, paving the way toward simplified integration into a unified, consolidated data space of high value. KW - Semantic Interoperability KW - Data Spaces KW - Integration Workflows KW - MaterialDigital PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-622952 DO - https://doi.org/10.1002/adem.202401092 SN - 1527-2648 SP - 1 EP - 25 PB - Wiley-VCH CY - Weinheim AN - OPUS4-62295 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Janssen, J. A1 - Makarov, E. A1 - Hickel, Tilmann A1 - Shapeev, A.V. A1 - Neugebauer, J. T1 - Automated optimization and uncertainty quantification of convergence parameters in plane wave density functional theory calculations N2 - First principles approaches have revolutionized our ability in using computers to predict, explore, and design materials. A major advantage commonly associated with these approaches is that they are fully parameter-free. However, numerically solving the underlying equations requires to choose a set of convergence parameters. With the advent of high-throughput calculations, it becomes exceedingly important to achieve a truly parameter-free approach. Utilizing uncertainty quantification (UQ) and linear decomposition we derive a numerically highly efficient representation of the statistical and systematic error in the multidimensional space of the convergence parameters for plane wave density functional theory (DFT) calculations. Based on this formalism we implement a fully automated approach that requires as input the target precision rather than convergence parameters. The performance and robustness of the approach are shown by applying it to a large set of elements crystallizing in a cubic fcc lattice. KW - Ab initio simulations KW - High throughput KW - convergence parameter PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618632 DO - https://doi.org/10.1038/s41524-024-01388-2 VL - 10 IS - 1 SP - 1 EP - 11 PB - Springer Science and Business Media LLC AN - OPUS4-61863 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hickel, Tilmann T1 - Application of Density Functional Theory in the Context of Phase Diagram Modelling N2 - An important pillar for the modelling of phase diagrams is the availability of accurate thermodynamic data for the individual phases. While experimental calorimetry is a powerful technique, a prediction of materials behavior solely on the computer, i.e. complementary to experimental investigations, has its own advantages. It allows one to resolve uncertainties in experimental data, to develop physical thermodynamic models and to determine free energies of phases that are not stable in reality. For this purpose, density functional theory (DFT), which does not require any experimental or empirical fit parameters, is the method of choice. Its advantage is to take the quantum-mechanical solution for the electronic wave functions as a starting point, when determining the chemical bonding of atoms. In the first part of the talk, I will speak about enthalpies of formation resulting from this approach, the underlying approximations, the achievable accuracies, as well as the typical incorporation into Calphad assessments. We note, however, that a disadvantage of DFT is the restriction of the method to T = 0 K in their original formulation. Phase stabilities of real materials, on the other hand, are often dominated by processes that are due to finite temperatures. To include temperature effects in DFT, a significant method development was necessary in the last decade. In the second part of this talk, I will therefore provide the basic concepts for the calculation of vibrational, electronic, and magnetic entropy contributions. I will also highlight some recent methodological achievements in this field and show how these methods opened new routes in understanding and characterizing materials. At the end a few examples of ab initio based phase diagrams will be discussed. The focus will be on phase stabilities and microstructure formation in Ni-based materials. The advantages of combining theoretical, experimental and Calphad concepts will be particularly emphasized. T2 - MSIT Winter School on Materials Chemistry CY - Tegernsee, Germany DA - 21.01.2024 KW - Ab initio simulations KW - CALPHAD KW - Thermodynamics KW - Free energies PY - 2024 AN - OPUS4-62729 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -