High-pressure phase transition and properties of spinel ZnMn2O4

S. Åsbrink, A. Waśkowska, L. Gerward, J. Staun Olsen, and E. Talik
Phys. Rev. B 60, 12651 – Published 1 November 1999
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Abstract

X-ray photoelectron spectroscopy, magnetic measurements, and a single-crystal x-ray structure determination at normal pressure have shown that Jahn-Teller active manganese ions in ZnMn2O4 are present in one valence state (III) on the octahedral sites of the spinel structure. The high-pressure behavior of ZnMn2O4 was investigated up to 52 GPa using the energy-dispersive x-ray diffraction technique and synchrotron radiation. The structural first-order phase transition from the body-centered to primitive-tetragonal cell takes place at Pc=23GPa. The high-pressure phase is metastable down to normal pressure. The c/a ratio reduces from 1.62 to 1.10 above Pc and remains nearly pressure independent in the high-pressure phase. The transition is attributed to the changes in electron configuration of the Mn3+ ions. According to the crystal field theory, the eg electron of octahedrally coordinated Mn3+ is either in the dz2 orbital or in the dx2y2. In the first configuration the MnO6 octahedron will be elongated and this is the case at normal pressure, while the second configuration gives the flattened octahedron. In the high-pressure phase some proportion of the eg electrons of the Mn3+ ions is moved to the dx2y2 level, which is revealed as an abrupt fall of observed magnitude of the distortion of the bulk crystal above Pc.

  • Received 16 June 1999

DOI:https://doi.org/10.1103/PhysRevB.60.12651

©1999 American Physical Society

Authors & Affiliations

S. Åsbrink*

  • Department of Inorganic Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden

A. Waśkowska

  • Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50 950 Wrocław, Poland

L. Gerward

  • Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark

J. Staun Olsen

  • Niels Bohr Institute, Ørsted Laboratory, University of Copenhagen, 2100 Copenhagen, Denmark

E. Talik

  • Institute of Physics, Silesian University in Katowice, 40 007 Katowice, Poland

  • *Deceased.

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Vol. 60, Iss. 18 — 1 November 1999

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