在CuO中超交互驱动的负热膨胀的机理洞察
Yuanpeng Zhang1,2, Marshall McDonnell1, Stuart A Calder1
1Neutron Scattering Division , Oak Ridge National Laboratory (ORNL) , Oak Ridge , Tennessee 37831 , United States.
Journal of the American Chemical Society
|April 2, 2019
概括
铜氧化物 (CuO) 的负热膨胀是由电子转移驱动的. 这种在特定方向上增强的超级交换相互作用导致CuO在加热时收缩,为材料特性提供了新的控制.
科学领域:
- 材料科学
- 凝聚物质物理学
- 固态化学
背景情况:
- 负热膨胀 (NTE) 是一种反直觉的现象,材料在加热时收缩.
- 铜氧化物 (CuO) 呈现NTE,但底层机制,特别是旋网合和NTE之间的联系,仍然不清楚.
研究的目的:
- 阐明CuO负热膨胀背后的机制.
- 调查网合和CuO中的NTE之间的关系.
- 在CuO中确定NTE的关键因素.
主要方法:
- 进行中子散射实验以探测磁相互作用.
- 主要应变轴分析以确定方向热膨胀.
- 密度函数理论 (DFT) 计算以建模电子和磁性特性.
主要成果:
- 随着温度的下降,电子转移显著增强了沿着 [101̅] 方向的超交换相互作用.
- 这种沿着 [101̅] 的增强相互作用被认为是CuO中NTE的主要驱动因素.
- 只有当 [101̅] 超交换途径优于竞争性磁相互作用时,才会发生 NTE.
结论:
- 该研究通过电子转移驱动的超交换相互作用来解释CuO中的NTE.
- 这些发现突显了自旋格子合和定向磁相互作用在控制热膨胀方面的关键作用.
- 结果表明通过超交换相互作用操纵热膨胀的潜在策略,例如光学操纵或兴奋剂.
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