1. High-pressure synthesis, crystal structure, and unusual valence state of novel perovskite oxide CaCu3Rh4O12.
- Author
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Yamada I, Ochi M, Mizumaki M, Hariki A, Uozumi T, Takahashi R, and Irifune T
- Subjects
- Calcium Compounds chemistry, Hot Temperature, Oxides chemical synthesis, Powder Diffraction, Pressure, Titanium chemistry, X-Ray Absorption Spectroscopy, Calcium Compounds chemical synthesis, Oxides chemistry
- Abstract
A novel perovskite oxide, CaCu3Rh4O12, has been synthesized under high-pressure and high-temperature conditions (15 GPa and 1273 K). Rietveld refinement of synchrotron X-ray powder diffraction data indicates that this compound crystallizes in a cubic AA'3B4O12-type perovskite structure. Synchrotron X-ray absorption and photoemission spectroscopy measurements reveal that the Cu and Rh valences are nearly trivalent. The spectroscopic analysis based on calculations suggests that the appropriate ionic model of this compound is Ca(2+)Cu(∼2.8+)3Rh(∼3.4+)4O12, as opposed to the conventional Ca(2+)Cu(2+)3Rh(4+)4O12. The uncommon valence state of this compound is attributed to the relative energy levels of the Cu 3d and Rh 4d orbitals, in which the large crystal-field splitting energy of the Rh 4d orbitals is substantial.
- Published
- 2014
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