Phase Stability, Phase Transformations, and Reactive Phase Formation in Electronic Materials XX: Phase Stability of Energy Materials
Sponsored by: TMS Functional Materials Division, TMS Structural Materials Division, TMS: Alloy Phases Committee
Program Organizers: Hiroshi Nishikawa, Osaka University; Shih-kang Lin, National Cheng Kung University; Chao-Hong Wang, National Chung Cheng University; Chih-Ming Chen, National Chung Hsing University; Jaeho Lee, Hongik University; Zhi-Quan Liu, Shenzhen Institutes of Advanced Technology; Ming-Tzer Lin, National Chung Hsing University; Dajian Li, Karlsruhe Institute of Technology; Yu Zhong, Worcester Polytechnic Institute; Yee-wen Yen, National Taiwan University of Science and Technology; A.S.Md Abdul Haseeb, Bangladesh University of Engineering and Technology (BUET); Ligang Zhang, Central South University; Sehoon Yoo, Korea Institute of Industrial Technology; Vesa Vuorinen, Aalto University; Yu-Chen Liu, National Cheng Kung University
Thursday 2:00 PM
March 18, 2021
Room: RM 21
Location: TMS2021 Virtual
Session Chair: Yu-chen Liu, National Cheng Kung University; Zhi-Quan Liu, Shenzhen Institutes of Advanced Technology
2:00 PM Invited
Towards Predictive Solid-state Synthesis: Understanding Phase Evolution during the Formation of YBCO: Christopher Bartel1; 1University of California, Berkeley
Solid-state synthesis is the bedrock of inorganic materials chemistry and an integral component of materials design. However, this approach is typically a “black box”, where the only observation is what formed from the precursor materials after a reaction at a predetermined set of conditions. In order to rationally synthesize new inorganic materials, it is critical to not only understand but predict what intermediates form and how they influence the reaction towards the synthesized phase(s). Using in situ synchrotron X-ray diffraction and transmission electron microscopy, we are able to show the evolution of phases during YBCO synthesis for the first time. Importantly, at each step of the synthesis pathway, we rationalize phase evolution within a thermodynamic framework built upon density functional theory calculations and a machine-learned descriptor for compound thermochemistry.
2:30 PM
Machine Learning for Perovskite Phase Stability: Dane Morgan1; Wei Li2; Ryan Jacobs1; 1University of Wisconsin-Madison; 2Google
Machine learning methods are a powerful tool to rapidly predict phase stability, particularly when large amounts of calculated stability data are available. In this talk I will discuss recent work on predicting formation energies of perovskite structures[1]. We use combinations of elemental features and find that an extra trees method yields a good 5-fold cross-validation accuracy on energy above the convex hull. We then demonstrate that the cross-validation is a very optimistic estimate appropriate only for those chemistries that are well-represented in the data set. This work illustrates some of the capabilities for machine learning to predict stability but also the challenges of extrapolation to new chemistries.[1] 1. Li, W., Jacobs, R. & Morgan, D. Predicting the thermodynamic stability of perovskite oxides using machine learning models. Computational Materials Science 150, 454–463 (2018). DOI: 10.1016/j.commatsci.2018.04.033
2:50 PM
Vertically Stacked 2H-1T Dual-phase TMD Microstructures during Lithium Intercalation: A First Principles Study: Shayani Parida1; Avanish Mishra1; Jie Chen1; Jin Wang1; Arthur Dobley2; Barry Carter3; Avinash Dongare1; 1University Of Connecticut; 2EaglePicher Technologies LLC; 3Sandia National Laboratories
Layered transition-metal dichalcogenides (TMDs) have shown promise to replace carbon-based compounds as suitable anode materials for Lithium-ion batteries (LIBs). While the intercalation mechanism of Li in mono- and bi-layer TMDs have been thoroughly examined, mechanistic understanding of Li intercalation induced phase transformation in bulk or thin films of TMDs is still largely unexplored. This study investigates possible scenarios during sequential Li intercalation and aims to gain a mechanistic understanding of the phase transformation in bulk TMDs using density functional theory (DFT) calculations. The role of concentration and distribution of Li-ions on the formation of in-plane and out-of-plane phase boundaries as well as resultant structural modifications have been examined. The study demonstrates that lithiation would proceed in a systematic layer-by-layer manner wherein Li-ions diffuse into successive interlayer spacings to render local phase transformation of the adjacent TMD layers leading to the formation of dual-phase microstructures with stable interfaces.
3:10 PM
Study on the Phase Diagrams of Bi-Te-RE (Yb, La, Ce, Nd, Sm, Tb, Er) Systems: Ligang Zhang1; Mingyue Tan1; Cun Mao1; Libin Liu1; 1Central South University
Bi-Te base alloy is one of the most mature thermoelectric materials at present. In this work，the Bi-Te phase diagram was determined by equilibrium alloy method. Experimental result shows that there is a β-phase with a large composition range at low temperature, while Bi2Te and Bi4Te3 are relatively stable in the solid-liquid region. Isothermal sections of Bi-Te-RE (Yb, La, Ce, Nd, Sm, Tb, Er) ternary systems at 573K and 673K were determined by equilibrium alloy method, combined with microprobe analysis and X-ray diffraction. The maximum solid solubility of Yb in Bi2Te3 and β is about 0.3 at% at 573K and about 0.4 at% at 673K. Ternary compounds with equi-atomic ratio (BiTeRE) were found in the Bi-Te-RE(RE=La,Ce,Nd) systems. The La-Te and Ce-Te binary compounds exhibit a large solid solubility of Bi. The solid solubility of RE elements in Bi-Te matrix increases with the decrease of the atomic radius of rare earth elements.
3:30 PM
The Significance of Transport Electronic Entropy in VO2: Jonathan Paras1; Antoine Allanore1; 1Massachusetts Institute of Technology
Thermodynamics of metal-insulator transitions (MITs) has proven difficult to model. While calorimetric studies have improved our understanding of the enthalpic contribution to these types of transitions, the relative importance of the vibrational and electronic contribution to the entropy of transformation remain in dispute. VO2 is an exemplary material that undergoes an MIT at 340 K, experiencing a significant change in its electronic transport properties, suggesting a corresponding change in the electronic structure. Whereas density functional theory has had considerable difficulty in systems with correlated electrons, a thermodynamic relationship is presented that links measured electronic transport properties to the relative change in the electronic state entropy. Estimation of the vibrational entropy is conducted using experimental calorimetric data. The calculated electronic entropy coupled with estimates of the vibrational entropy change agree reasonably well with the total entropy change determined through calorimetry.
3:50 PM
Electric Current Effect on the High-strain-rate Deformation of AA7075-T6 Al-alloy: Yu-Ching Chen1; Kuan-hsueh Lin1; Yu-Chen Liu1; Tong Chen1; Ting-Ju Chen1; Woei-Shyan Lee1; Shih-Kang Lin1; 1National Cheng Kung University
AA7075-T6 Al-alloy is a light material in the application of public transportation. However, the mechanical strength of Al-alloy is rather low to resist impact during traffic accident. Electric-current assisted manufacturing is attracting more attention nowadays. In this study, in situ high speed compression tests of electric current were performed using Split Hopkinson Pressure Bar to produce high-strain-rate deformation. Results showed that deformed AA7075-T6 samples with electric current passing through could endure larger plastic deformation, while the ones without electric current were severely shattered. We found precipitations formed at the sub-grain boundary diminished in the deformed alloy with electric current assisted with TEM analysis. The pole figure analysis via EBSD suggested that the alloys deformed without electric current assisted had a twin-like orientation while the ones with electric current assisted had a more random orientation. Overall, we show the potential of using electric current to enhance the impact-resistance of Al-alloy.