强大的低能量声模式使得在一个有序的固体中具有类似液体的超低导热率
Peng-Fei Liu1,2, Xiyang Li3,4, Jingyu Li1,2
1Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
National science review
|November 18, 2024
概括
研究人员在晶体CsAg5Te3中发现了类似液体的热传输,从而实现了超低的晶格导热率 (κL). 这一发现挑战了传统的理解,并为热电材料开辟了新的途径.
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:
- 低晶格导热率 (κL) 对于热电和热屏障应用至关重要.
- 子分散通常限制了晶体固体中 κL 的低值.
- 现有的理论,如皮尔尔斯理论,描述热传输,但可能无法捕捉所有现象.
研究的目的:
- 调查晶体CsAg5Te3.3中极低格子导热率背后的机制.
- 探索在有序晶体材料中类似液体的热传输的可能性.
- 了解特定的声子模式和原子振动在热传导中的作用.
主要方法:
- 结晶的CsAg5Te3.3的实验合成和表征.
- 第一个原则的计算,以模拟声的行为和相互作用.
- 不弹性中子散射测量以探测声子散射和动态.
- 应用双通道模型来分析热传输贡献.
主要成果:
- 在CsAg5Te3.3中实现了极低的网格导热率 (κL) ~0.18 Wm-1K-1
- 识别了低的光学声模式 (~3.1 meV),可以避免与声学声交叉.
- 观察到弱结合的银 (Ag) 原子具有大,热诱导的振动幅度.
- 证明局部化的粒子状声模式和波状声之间的合控制着热传输.
结论:
- 这项研究揭示了在一个有序的晶体固体中类似液体的热传递.
- 软的结构框架和的Ag原子有助于抑制热传导.
- 观察到的行为明显偏离了皮尔尔斯理论预测的标准1/T温度依赖.
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