1. Spin-state transition in Ba2Co9O14.
- Author
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Cheng, J.-G., Zhou, J.-S., Hu, Z., Suchomel, M. R., Chin, Y. Y., Kuo, C. Y., Lin, H.-J., Chen, J. M., Pi, D. W., Chen, C. T., Takami, T., Tjeng, L. H., and Goodenough, J. B.
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PHASE transitions , *NUCLEAR spin , *BARIUM compounds , *COBALT compounds , *THERMOELECTRICITY , *HIGH temperatures , *MAGNETIC susceptibility - Abstract
Ba2Co9O14 is a charge-ordered Co2+/3+ cobaltite that consists of building blocks of Cdl2-type Co2+/3+O6/3 layers, face-shared Co3+3O12 octahedral trimers, and corner-sharing Co2+04 tetrahedra. The Co-L2,3 x-ray absorption spectroscopy spectrum at room temperature indicates a high and a low spin state for Co2+ and Co3+ ions, respectively. Measurements of high-temperature resistivity and thermoelectric power revealed an insulator-to-insulator phase transition at Tt = 570 K, above which the inverse magnetic susceptibility X-1(T) deviates from the Curie-Weiss law. By using a combination of soft x-ray absorption spectroscopy at the O-K edge and high-resolution synchrotron x-ray powder diffraction measurements on crossing Tt, we have successfully determined the origin of this phase transition as a low-to-higher spin-state transition of Co3+ ions within the face-shared Co3O12 octahedral trimers in Ba2Co9O14. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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