title: Charge transfer in spinel Co3O4 at high pressures.
abstract: Charge transfer in cobalt oxide Co(3)O(4) in the spinel structure is evidenced by experimental results using x-ray diffraction (XRD), x-ray absorption near edge structure (XANES) spectroscopy, and Raman scattering at high pressures up to 42.1, 24.6 and 35.1 GPa, respectively. While the cubic structure was found to persist under pressure up to 42.1 GPa based on the XRD and Raman results, the mode Grüneisen parameter was calculated according to our Raman measurements. Our structural data refinement revealed a structural transition from the normal spinel structure at low pressures to a partially inverse spinel structure at pressures above 17.7 GPa. This transition may be caused by the interaction of charges between tetrahedral and octahedral sites via a charge transfer process. Evidence for the charge transfer process is further supported by changes of the pre-edge features in the XANES data.
authors.affiliation: Department of Physics and Astronomy, University of Nevada Las Vegas and High Pressure Science and Engineering Center (HiPSEC), Las Vegas, NV 89154-4002, USA. BaiLg@hpcat.aps.anl.gov
authors.forename: Ligang
authors.initials: L
authors.lastname: Bai
authors.forename: Michael
authors.initials: M
authors.lastname: Pravica
authors.forename: Yusheng
authors.initials: Y
authors.lastname: Zhao
authors.forename: Changyong
authors.initials: C
authors.lastname: Park
authors.forename: Yue
authors.initials: Y
authors.lastname: Meng
authors.forename: Stas V
authors.initials: SV
authors.lastname: Sinogeikin
authors.forename: Guoyin
authors.initials: G
authors.lastname: Shen