结构相位转换和Ba2GdNbO6的磁性表征用于低温磁热制冷
Fiamma Berardi1, Liam A V Nagle-Cocco1, James M A Steele2,1
1Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0US, U.K.
Chemistry of materials : a publication of the American Chemical Society
|November 17, 2025
概括
这项研究揭示了Ba2GdNbO6在室温下呈现四边形对称性,在冷却时转变为单边形,在加热时转变为立方形. 由于其磁性特性,它显示出低温磁热制冷的前景.
科学领域:
- 材料科学 材料科学 材料科学
- 固态化学 固态化学
- 晶体学 晶体学是指结晶学.
- 磁力学 磁力学 是一种
背景情况:
- 在室温下,Ba2GdNbO6的晶体结构之前已经报告了不同的对称性 (单临床,四角形,立方形).
- 了解精确的结构阶段及其过渡对于探索双矿材料的潜在应用至关重要.
研究的目的:
- 为了精确地确定 Ba2GdNbO6.6 的室温晶体结构.
- 为了研究Ba2GdNbO6.6的温度依赖的结构相变.
- 描述Ba2GdNbO6的磁性特性和磁热效应,用于潜在的应用.
主要方法:
- 高分辨率的同步龙X射线衍射.
- 中子衍射和中子对分布函数分析.
- 测量磁性易感度和热容量.
主要成果:
- 在室温下,Ba2GdNbO6采用四边形I4 / m双矿结构,具有微妙的Jahn-Teller扭曲.
- 在冷却到2.4K时发生向单临P21/n对称的相位过渡,在加热到~450K时发生向立方Fm-3m对称的可逆过渡.
- 该化合物表现出具有弱铁磁相关性和2K和9T时最大磁变化为-15.75J K-1 mol-1,表明显著的磁热潜力.
结论:
- Ba2GdNbO6具有不同的结构相,取决于温度,在室温下具有稳定的四角形相.
- 该材料表现出有前途的磁热性质,包括显著的磁变化和热温度变化.
- 由于其有效的冷却能力,Ba2GdNbO6是低温磁热制冷应用的强有力的候选者.
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