在和四博酸盐中重新审视固体-固体相变,用于储存热能
Sumit Konar1, Gertruda Zieniute1, Elliot Lascelles1
1Joseph Banks Laboratories, School of Chemistry, University of Lincoln, Lincoln LN6 7DL, United Kingdom.
概括
这项研究研究了使用X射线衍射的和四甲酸相过渡. 这两种材料在整个加热-冷却周期中都表现出良好的热和结构稳定性,并确定了不同的高温阶段.
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.
背景情况:
- 四甲酸和四甲酸 (NaBF4和KBF4) 是无机盐,在各种领域都有潜在的应用.
- 了解它们在热应力下的结构行为对于材料设计和性能评估至关重要.
研究的目的:
- 为了阐明NaBF4和KBF4的固体-固体相变,使用现场同步子粉X射线衍射 (PXRD).
- 为了确定 NaBF4.4 的高温 (HT) 阶段的晶体结构.
- 研究这些材料的热膨胀和导电性质.
主要方法:
- 在多个加热-冷却周期中进行现场同步粉X射线衍射 (PXRD).
- 不同扫描热量计 (DSC) 用于相位过渡温度验证.
- 瑞特维尔德精细化用于网格参数确定和热膨胀计算.
- 密度函数理论 (DFT) 分子动力学 (MD) 模拟.
- 在室温下测量导热率.
主要成果:
- 通过PXRD (NaBF4~240°C,KBF4~290°C) 确定的相位过渡温度与DSC数据保持一致.
- NaBF4的HT失序阶段被确定为六角形,空间组P63/mmc.
- MD模拟支持P63/mmc结构,并揭示了F原子在无序状态中的更高流动性.
- 在HT-NaBF4中异常热膨胀显示了a-b平面的收缩和c方向的膨胀.
- 室温导热率为NaBF4的0.8-1.0 W m-1 K-1和KBF4.4的0.55-0.65 W m-1 K-1.
结论:
- 在多个加热-冷却周期中,NaBF4和KBF4具有良好的热和结构稳定性.
- 确定的晶体结构和热特性为它们的潜在应用提供了宝贵的见解.
- 这项研究突出了四二酸盐复杂的结构动态和热行为.
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