title: Charge disproportionation and the pressure-induced insulator-metal transition in cubic perovskite PbCrO3.
abstract: The perovskite PbCrO3 is an antiferromagnetic insulator. However, 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. We report 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. We argue that a charge disproportionation 3Cr(4+) → 2Cr(3+) + Cr(6+) in association with the 6s-p hybridization on the Pb(2+) 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.affiliation: Materials Science and Engineering Program and Texas Materials Institute, University of Texas at Austin, Austin, TX 78712; Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan;
authors.forename: Jinguang
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Chemical Engineering and Texas Materials Institute, University of Texas at Austin, Austin, TX 78712;
authors.forename: K E
authors.initials: KE
authors.lastname: Kweon
authors.affiliation: Materials Science and Engineering Program and Texas Materials Institute, University of Texas at Austin, Austin, TX 78712;
authors.forename: S A
authors.initials: SA
authors.lastname: Larregola
authors.affiliation: Advanced Photo Source, Argonne National Laboratory, Argonne, IL 60439;
authors.forename: Yang
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Materials Science and Engineering Program and Texas Materials Institute, University of Texas at Austin, Austin, TX 78712;
authors.forename: Y
authors.initials: Y
authors.lastname: Shirako
authors.affiliation: Materials Science and Engineering Program and Texas Materials Institute, University of Texas at Austin, Austin, TX 78712; Department of Chemical Engineering, Northeastern University, Boston, MA 02115; and.
authors.forename: L G
authors.initials: LG
authors.lastname: Marshall
authors.affiliation: Materials Science and Engineering Program and Texas Materials Institute, University of Texas at Austin, Austin, TX 78712;
authors.forename: Z-Y
authors.initials: ZY
authors.lastname: Li
authors.affiliation: Materials Science and Engineering Program and Texas Materials Institute, University of Texas at Austin, Austin, TX 78712;
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.affiliation: Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831.
authors.forename: António M
authors.initials: AM
authors.lastname: dos Santos
authors.affiliation: Advanced Photo Source, Argonne National Laboratory, Argonne, IL 60439;
authors.forename: M R
authors.initials: MR
authors.lastname: Suchomel
authors.affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan;
authors.forename: K
authors.initials: K
authors.lastname: Matsubayashi
authors.affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan;
authors.forename: Y
authors.initials: Y
authors.lastname: Uwatoko
authors.affiliation: Chemical Engineering and Texas Materials Institute, University of Texas at Austin, Austin, TX 78712;
authors.forename: G S
authors.initials: GS
authors.lastname: Hwang
authors.affiliation: Materials Science and Engineering Program and Texas Materials Institute, University of Texas at Austin, Austin, TX 78712; jgoodenough@mail.utexas.edu jszhou@mail.utexas.edu.
authors.forename: John B
authors.initials: JB
authors.lastname: Goodenough
authors.affiliation: Materials Science and Engineering Program and Texas Materials Institute, University of Texas at Austin, Austin, TX 78712; jgoodenough@mail.utexas.edu jszhou@mail.utexas.edu.
authors.forename: J-S
authors.initials: JS
authors.lastname: Zhou
keywords: charge disproportionation; high pressure; insulator–metal transition; perovskite