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Raman scattering study of charge ordering in beta-Ca0.33V2O5

Z. V. Popovic·M. J. Konstantinovic·V. V. Moshchalkov·M. Isobe·Y. Ueda
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Abstract

Polarized Raman spectra of the calcium vanadium oxide bronze beta-Ca0.33V2O5 are measured in the temperature range between 300 K and 20 K. The charge ordering phase transition at about 150 K is characterized by the appearance of the new Raman-active modes in the spectra, and by anomalies in the electronic background scattering. The high temperature Raman scattering spectra of beta-Ca0.33V2O5 are in apparent resemblance with those of alpha'-NaV2O5, which suggests that there is a similar charge-phonon dynamics in both compounds. The study of dynamical properties and the symmetry analysis of the Raman modes show that in the mixed valence state of beta-Ca0.33V2O5 the electrons are delocalized into V1-O5-V3 orbitals. We propose that in the charge ordered state below 150 K the d-electrons localize within V1-V3 ladders, either in "zig-zag" fashion like in alpha'-NaV2O5 or in the forms of the double chains like in gamma-LiV2O5.

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Z. V. Popovic, M. J. Konstantinovic, V. V. Moshchalkov, M. Isobe, Y. Ueda. 2003-01-24. Raman scattering study of charge ordering in beta-Ca0.33V2O5. https://doi.org/10.1088/0953-8984%2F15%2F6%2F101

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