Pressure-Induced YbFe2O4-Type to Spinel Structural Change of InGaMgO4

Koike, T. Das, H. Oka, K. Kusano, Y. Cubillas, F. Bojorqez, F. B. Alvarez-Montano, V. E. Ito, S. Shigematsu, K. Togano, H. Yamada, I. Ishibashi, H. Kubota, Y. Mori, S. Kimizuka, N. Azuma, M.

Spinel-type InGaMgO4 with a = 8.56615(3) Å was prepared by treating layered YbFe2O4type InGaMgO4 at 6 GPa and 1473 K. DFT calculation and Rietveld analysis of synchrotron X-ray powder diffraction data revealed the inverse spinel structure with In3+:Ga3+/Mg2+ = 0.726:0.274 in the tetrahedral site and 0.137:0.863 in the octahedral site. InGaMgO4 spinel is an insulator with an experimental band gap of 2.80 eV, and the attempt at hole doping by post-annealing in a reducing atmosphere to introduce an oxygen defect was unsuccessful. This is the first report of the bulk synthesis of AB2O4 compounds with both YbFe2O4 and spinel polymorphs.

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