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High-pressure synthesis, crystal structure determination, and a Ca substitution study of the metallic rhodium oxide NaRh2O4

K. Yamaura·Q. Huang·M. Moldovan·D. P. Young·A. Sato·Y. Baba·Y. Matsui·E. Takayama-Muromachi
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Abstract

The sodium rhodate NaRh2O4 was synthesized for the first time and characterized by neutron and x-ray diffraction studies, measurements of magnetic susceptibility, specific heat, electrical resistivity, and the Seebeck coefficient. NaRh2O4 crystallizes in the CaFe2O4-type structure, which is comprised of a characteristic RhO6 octahedra network. The compound is metallic in nature, probably reflecting the 1 to 1 mixed valence character of Rh(III) and Rh(IV) in the network. For further studies of the compound, the Rh valence was varied significantly by means of an aliovalent substitution: the full range solid solution between NaRh2O4 and CaRh2O4 was achieved and characterized as well. The metallic state was dramatically altered, and a peculiar magnetism developed in the low Na concentration range.

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K. Yamaura, Q. Huang, M. Moldovan, D. P. Young, A. Sato, Y. Baba, Y. Matsui, E. Takayama-Muromachi. 2004-10-28. High-pressure synthesis, crystal structure determination, and a Ca substitution study of the metallic rhodium oxide NaRh2O4. https://arxiv.org/abs/cond-mat/0410742

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