电子掺杂的钙钛矿型PbVO中的巨大负热膨胀

Colossal Negative Thermal Expansion in Electron-Doped PbVO Perovskites.

作者信息

Yamamoto Hajime, Imai Takashi, Sakai Yuki, Azuma Masaki

机构信息

Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.

Present address: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira2-1-1, Aoba-ku, Sendai, 980-8577, Japan.

出版信息

Angew Chem Int Ed Engl. 2018 Jul 2;57(27):8170-8173. doi: 10.1002/anie.201804082. Epub 2018 Jun 11.

DOI:10.1002/anie.201804082

PMID:29749074

Abstract

Colossal negative thermal expansion (NTE) with a volume contraction of about 8 %, the largest value reported so far for NTE materials, was observed in an electron-doped giant tetragonal perovskite compound Pb Bi VO (x=0.2 and 0.3). A polar tetragonal (P4mm) to non-polar cubic structural transition took place upon heating. The coefficient of thermal expansion (CTE) and the working temperature could be tuned by changing the Bi content, and La substitution decreased the transition temperature to room temperature. Pb La Bi VO exhibited a unit cell volume contraction of 6.7 % from 200 K to 420 K. Interestingly, further gigantic NTE of about 8.5 % was observed in a dilametric measurement of a Pb La Bi VO polycrystalline sample. The pronounced NTE in the sintered body should be attributed to an anisotropic lattice parameter change.

摘要

在电子掺杂的巨四方钙钛矿化合物PbBiVO（x = 0.2和0.3）中观察到了巨大的负热膨胀（NTE），体积收缩约8％，这是迄今为止报道的NTE材料的最大值。加热时发生了从极性四方（P4mm）到非极性立方的结构转变。热膨胀系数（CTE）和工作温度可以通过改变Bi含量来调节，并且La替代将转变温度降低到室温。PbLaBiVO在200K至420K范围内表现出6.7％的单位晶胞体积收缩。有趣的是，在PbLaBiVO多晶样品的膨胀测量中观察到约8.5％的进一步巨大NTE。烧结体中明显的NTE应归因于各向异性的晶格参数变化。