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Title: Charge disproportionation and the pressure-induced insulator–metal transition in cubic perovskite PbCrO 3

The perovskite PbCrO3 is an antiferromagnetic insulator. But, the fundamental interactions leading to the insulating state in this single-valent perovskite are unclear. Moreover, the origin of the unprecedented volume drop observed at a modest pressure of P = 1.6 GPa remains an outstanding problem. Our report shows a variety of in situ pressure measurements including electron transport properties, X-ray absorption spectrum, and crystal structure study by X-ray and neutron diffraction. These studies reveal key information leading to the elucidation of the physics behind the insulating state and the pressure-induced transition. Furthermore, we argue that a charge disproportionation 3Cr4+ → 2Cr3+ + Cr6+ in association with the 6s-p hybridization on the Pb2+ is responsible for the insulating ground state of PbCrO3 at ambient pressure and the charge disproportionation phase is suppressed under pressure to give rise to a metallic phase at high pressure. The model is well supported by density function theory plus the correlation energy U (DFT + U) calculations.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [3] ;  [3] ;  [3] ;  [5] ;  [4] ;  [6] ;  [6] ;  [2] ;  [3] ;  [3]
  1. Univ. of Texas, Austin, TX (United States). Materials Science and Engineering Program and Texas Materials Inst.; Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics; Univ. of Tokyo (Japan). Inst. for Solid State Physics
  2. Univ. of Texas, Austin, TX (United States). Chemical Engineering and Texas Materials Inst.
  3. Univ. of Texas, Austin, TX (United States). Materials Science and Engineering Program and Texas Materials Inst.
  4. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division
  6. Univ. of Tokyo (Japan). Inst. for Solid State Physics
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AC02-06CH11357
Type:
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 112; Journal Issue: 6; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; high pressure; perovskite; insulator-metal transition; charge disproportionation; LARGE-VOLUME; MICROSTRUCTURE; SPECTROSCOPY; CHROMIUM; CRYSTAL
OSTI Identifier:
1235506
Alternate Identifier(s):
OSTI ID: 1334440