Ab initio cluster calculations of Co3+ spin states in RBaCo2O5.5 (R=Ho, Gd) |
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Authors: | L Siurakshina B Paulus V Yushankhai |
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Institution: | 1. Max-Planck-Institut für Physik Komplexer Systeme, N?thnitzer Stra?e 38, 01187, Dresden, Germany 2. Joint Institute for Nuclear Research, 141980, Dubna, Russia 3. Physikalische und Theoretische Chemie, Freie Universit?t Berlin, Takustra? 3, 14195, Berlin, Germany 4. Max-Planck-Institut für Chemische Physik fester Stoffe, N?thnitzer Stra?e 40, 01187, Dresden, Germany
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Abstract: | Two types of oxygen-deficient perovskites RBaCo2O5.5(R=Ho,Gd) related to the “122” type structure (a
p
× 2a
p
× 2a
p
) have been studied on the basis of ab initio cluster calculations. We consider the peculiar behavior of the trivalent ions
Co3+(3d
6) in either octahedral or pyramidal oxygen coordinations, which is related to a structural first-order phase transition in
both compounds. Relative energy positions of low spin (LS, S = 0), intermediate spin (IS, S = 1) and high spin (HS, S = 2) electron configurations are calculated for the low-and high-temperature lattice structures of RBaCo2O5.5. A combined analysis of the calculated results and experimental structural data leads to a simple model that captures the
most prominent features of the phase transition common to both compounds. |
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Keywords: | PACS" target="_blank">PACS 64 60 Ej 71 70 -d Level splitting and interactions 71 15 -m Methods of electronic structure calculations |
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