Colossal Negative Thermal Expansion in Electron-Doped PbVO3 Perovskites

Hajime Yamamoto; Takashi Imai; Yuki Sakai; Masaki Azuma

doi:10.1002/anie.201804082

Colossal Negative Thermal Expansion in Electron-Doped PbVO₃ Perovskites

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

Authors

Hajime Yamamoto^{1

2}, Takashi Imai¹, Yuki Sakai³, Masaki Azuma¹

Affiliations

¹ Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
² Present address: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira2-1-1, Aoba-ku, Sendai, 980-8577, Japan.
³ Kanagawa Institute of Industrial Science and Technology, 705-1 Shimoimaizumi, Ebina, 243-0435, Japan.

PMID: 29749074
DOI: 10.1002/anie.201804082

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_1-x Bi_x VO₃ (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_0.76 La_0.04 Bi_0.20 VO₃ 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_0.76 La_0.04 Bi_0.20 VO₃ polycrystalline sample. The pronounced NTE in the sintered body should be attributed to an anisotropic lattice parameter change.

Keywords: Jahn-Teller distortion; doping; perovskite phases; phase transitions; vanadates.

Publication types

Research Support, Non-U.S. Gov't