结合的MnCoGe基化合物中具有Ni2In型六角结构的巨大的负热膨胀
Ying-Ying Zhao1, Feng-Xia Hu, Li-Fu Bao
1Beijing National Laboratory for Condensed Matter Physics and State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences , Beijing 100190, P. R. China.
Journal of the American Chemical Society
|January 29, 2015
概括
CoGe化合物通过结构转变表现出巨大的负热膨胀 (NTE). 与环氧粉末的结合扩大了过渡,显著提高了NTE性能和工作温度范围.
科学领域:
- 材料科学 材料科学 材料科学
- 凝聚物质物理学 凝聚物质物理学
- 固态化学 固态化学
背景情况:
- 基于MnCoGe的化合物表现出巨大的负热膨胀 (NTE),与马氏体结构过渡有关.
- 之前的研究集中在磁热效应上,忽视了NTE的潜力,因为过渡温度窗口有限.
- 这些化合物的固有脆性阻碍了它们的实际应用.
研究的目的:
- 增强基于MnCoGe的化合物的负热膨胀 (NTE) 特性.
- 扩大NTE的操作温度窗口.
- 调查剩余压力对结构转型和NTE的影响.
主要方法:
- 高分辨率的中子衍射分析结构转变和单元细胞体积变化.
- 加入少量的环氧 (3-4%) 粘合粉末MnCoGe基材料.
- 结合样本中的热膨胀系数和工作温度窗口的表征.
主要成果:
- 通过环氧结合引入残余应力来实现一个巨大的NTE,扩大结构过渡.
- 在210K窗口 (122332K) 中,在MnCo0.98Cr0.02Ge.Ge中观察到平均线性NTE系数 (α̅) 为-51.5 × 10−6/K.
- 在室温 (250305 K) 附近,几乎恒定的α值达到了 -119 × 10−6/K,表明了出色的性能.
结论:
- 环氧诱导的残余应力有效地扩大了相位过渡,显著提高了NTE的性能.
- 实现的NTE性能,包括广泛的操作温度窗口和高系数,超过了之前报告的材料.
- 这些基于MnCoGe的增强材料对需要NTE的应用具有重大潜力,特别是用于补偿正热膨胀.
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