Fabrication of unique crystal including hydroxide group in hydrothermal process

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K05653
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 36010:Inorganic compounds and inorganic materials chemistry-related
• Research Institution: Kyushu University
• Principal Investigator: Inada Miki 九州大学, 中央分析センター(筑紫地区), 准教授 (40624979)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 水熱合成 / 水酸基化学 / 特異結晶

Outline of Final Research Achievements

The crystallization of cubic BaTiO3 via dissolution-reprecipitation of precursor could be suppressed by the addition of ethyleneglycol(EG), resulting in the formation of tetragonal BaTiO3 under hydrothermal treatment at 200°C. We found that the synthesized tetragonal BaTiO3 includes a much amount of OH group and the OH group influences the stability of BaTiO3 tetragonality. In order to clarify the effect of OH group on the tetragonality, crystal structure and morphology of BaTiO3, the structural analysis was carried out in this study.
XRD analysis indicates that the oxygen site of synthesized tetragonal BaTiO3 was partially occupied by OH ion. The OH content and c/a ratio increased by EG addition at hydrothermal treatment. The tetragonality of synthesized nanorod disappeared by heat treatment, indicating that substituted hydroxyl group stabilized the tetragonal crystalline structure.

Free Research Field

無機材料合成

Academic Significance and Societal Importance of the Research Achievements

水熱合成物中のOH基に着目し、結晶相との関連を明らかにした研究はこれまでになく、 “嫌われ者のOH基が役立つ”という申請者独自の発想である。本研究が達成できれば、OH基を活用した酸化物結晶の新規創製技術の拡大につながる。また、柱状結晶形態を活かした特殊フィラーとしての応用、OH基導入によるプロトン伝導性の発現、親水性付与による吸着特性の変化など、その材料系で見られなかった機能の発現が期待でき、波及効果は大きいと期待される。