超柔顺和柔软的（CH_{3}NH_{3}）_{3}Bi_{2}I_{9} 晶体，具有超低热导率。

Supercompliant and Soft (CH_{3}NH_{3})_{3}Bi_{2}I_{9} Crystal with Ultralow Thermal Conductivity.

机构信息

Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York 14853, USA.

Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061, USA.

出版信息

Phys Rev Lett. 2019 Oct 11;123(15):155901. doi: 10.1103/PhysRevLett.123.155901.

DOI:10.1103/PhysRevLett.123.155901

PMID:31702321

Abstract

In this Letter, we show the phonon dispersion of (CH_{3}NH_{3}){3}Bi{2}I_{9} single crystals at 300 K measured by inelastic x-ray scattering. The frequencies of acoustic phonons are among the lowest of crystals. Nanoindentation measurements verified that these crystals are very compliant and considerably soft. The frequency overlap between acoustic and optical phonons results in strong acoustic-optical scattering. All these features lead to an ultralow thermal conductivity. The fundamental knowledge obtained from this study will accelerate the design of novel hybrid materials for energy applications.

摘要

在这封信件中，我们展示了通过非弹性 X 射线散射测量得到的在 300K 下（CH_{3}NH_{3}）{3}Bi{2}I_{9}单晶的声子色散。声子的频率在晶体中是最低的。纳米压痕测量验证了这些晶体具有非常好的柔韧性和相当大的柔软度。声子和光学声子之间的频率重叠导致强烈的声-光散射。所有这些特性导致极低的热导率。从这项研究中获得的基本认识将加速为能源应用而设计新型混合材料。