Conversion from stable phase to metastable phase by temperature cycling

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03379
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13010:Mathematical physics and fundamental theory of condensed matter physics-related
• Research Institution: Kanazawa University (2023); Hokkaido University (2021-2022)
• Principal Investigator: Katsuno Hiroyasu 金沢大学, 学術メディア創成センター, 准教授 (70377927)
• Co-Investigator(Kenkyū-buntansha): 上羽 牧夫 愛知工業大学, 工学部, 教授 (30183213)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 結晶相転換 / 微小クラスタ反応 / 結晶サイズ分布 / 準安定相 / 結晶粉砕 / 温度変調

Outline of Final Research Achievements

When crystals of materials with some crystal structures, such as crystal polymorphs, are prepared by standard methods, the most stable structure are formed. In this study, we investigated a method to convert the most stable phase crystals into metastable structure phase crystals by a simple operation. Assuming crystal growth in a solution, mixed powder crystal of the most stable crystals and the metastable crystals are dispersed in a solution, and the temperature of a solution is changed periodically (temperature cycling). By taking into account the incorporation process of small clusters in addition to molecules, we theoretically show that it is possible to convert of stable crystals into energetically unfavorable metastable crystals, and we also clarify the mechanism of the conversion.

Free Research Field

結晶成長理論

Academic Significance and Societal Importance of the Research Achievements

本研究では，これまでカイラル結晶の転換として注目を集めていた現象を結晶一般に拡張し，エネルギー差のある２つの相の競合として捉えなおしている．安定相がエネルギー不利な準安定相へと転換されうるという非直感的な結果を理論的に示すことができた．
高機能材料は準安定構造をとるものも多く，その作りわけは成長過程を精密に制御する方法が取られている．この方法を使えば簡単な操作で一度できた不要な構造の結晶であっても目的とする構造へと変換が可能である．特に変換率が100％であるため，無駄がなく資源を効率的に使うことができる．