Research
Research Themes
Elucidation of the Mechanism of Giant Dielectric Constant and Material Design
Recently, materials showing giant dielectric constants (>103) have been reported, suggesting that it is possible to essentially improve the dielectric constant of bulk crystals by controlling the local compound defect structure. In this study, we focus on dielectric materials containing composite defects, and are developing a method to discover new dielectric materials by understanding the correlation between their local peculiar structures and dielectric properties through systematic calculations and compiling a database of such correlations.
- Y. Shimano, A. Kutana, R. Asahi, Scientific Reports 13, 22236 (2023).
- A. Kutana, Y. Shimano, R. Asahi, Scientific Reports 13, 3761 (2023).
Detailed Analysis of a-Si:H/c-Si Interface Using Machine Learning Potential Molecular Dynamics
SHJ contacts with a-Si:H passivation on crystalline silicon (c-Si) have been used as a means to improve the conversion efficiency of solar cell modules. However, various microscopic states exist at the a-Si:H/c-Si interface, such as non-bonded states, oxidation, and recrystallization, which affect the performance of solar cells. In this study, we use machine learning potentials to accelerate molecular dynamics simulations to create a structural model of the a-Si:H/c-Si interface and investigate the effects of recrystallization and insertion of oxygen at the interface during high temperature relaxation.
- T. Semba, J. McKibbin, R. Jinnouchi, R. Asahi, J. Mater. Res. 38, 5151 (2023).
Automatic Acquisition and Utilization of Bibliographic Information Using Natural Language Processing
Recently, research has been conducted on methods to extract desired information as structured data from literature texts, which are unstructured data, using natural language processing based on deep learning, and this technology has attracted attention as a technique to automatically and continuously construct databases necessary for MI. In this study, using the original corpus on superconductivity (SC-COMICS), material compositions, doping information, transition temperatures, and other information were extracted from 48,865 literature abstracts obtained from the article search site Scopus. Automatic slot extraction including transition temperature, doping information, process information, etc. is enabled. We have succeeded in constructing a transition temperature prediction model from the literature information and in obtaining process information that is highly relevant to the material composition.
- K. Yamaguchi, R. Asahi, Y. Sasaki, Adv Eng Inf. 54, 101768 (2022).
- K. Mitsui, Y. Sasaki, R. Asahi, STAM: Methods, 2206532 (2023).
Material Design of Ammonia Synthesis Catalysts
As expectations for renewable energy increase, ammonia is expected to become a candidate hydrogen carrier. In collaboration with our experimental group, we are developing a catalyst for ammonia synthesis that is more environmentally friendly than the conventional high-temperature, high-pressure process of Haber-Bosch.
>Courtesy of P. R. Varadwaj
Fluorinated electrolyte
Fluoride ion batteries are expected to be compact energy storage devices because they have a higher energy density than lithium ion batteries. They are also stable even at high temperatures and in overcharged conditions, and thus have a low risk of fire or explosion. In this laboratory, we are searching for novel fluoride ionic conductors in collaboration with experiments.
- T. Takami, C. Pattanathummasid, A. Kutana, R. Asahi, J. Phys.: Condens. Matter 35, 293002 (2023).
- C. Pattanathummasid, N. Yasufuku, R. Asahi, A. Kutana, M. Hagihara, K. Mori, T. Takami
Chemistry of Materials, 36, 5671 (2024).