Development of electrochemical hydrogen charge method and exploration of hydride superconductivity

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K18892
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 29:Applied condensed matter physics and related fields
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Shimizu Ryota 東京工業大学, 物質理工学院, 准教授 (70611953)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: 金属水素化物 / 複合アニオン化合物 / 薄膜物性 / 光機能

Outline of Final Research Achievements

We aimed to explore superconductivity by electrochemically adding high-density hydrogen, which is not achieved at ambient pressure, using Nb hydride as an electrode for hydrogen evolution in water electrolysis. However, the superconducting phase did not appear.
In contrast, we found attractive properties in multi-anion hydrides: In yttrium oxyhydride, which exhibits metal-insulator transition by ultraviolet light, we found a fast metal-insulator switching by electrochemical hydrogen insertion/desertion. In the titanium nitrogen-hydrogen compound, we observed a decrease in electrical resistivity by two orders of magnitude, which recovered to the original state immediately after the field cut. In the future, we aim to discover new electronic phases by cooling under an applied electric field.

Free Research Field

無機薄膜物性

Academic Significance and Societal Importance of the Research Achievements

本研究では、電気化学的水素チャージ法による金属水素化物の物性変調を目指し、特に光誘起金属化の観測に成功したイットリウム酸水素化物において、固体内水素の脱挿入による光学・電気特性変調に成功した。光・電場という複合的な外場が利用できること、従来数週間かかっていた緩和過程を10秒以内という5桁以上の高速なスイッチングを実現したことから、今後さらに全固体化できれば応用の可能性が拡大することが期待される成果である。