Studies on rare earth cobaltites, La1-xSrxCoO3 and related systems

Rao, C. N. R. ; Bhide, V. G. (1974) Studies on rare earth cobaltites, La1-xSrxCoO3 and related systems American Institute of Physics Conference Proceedings, 18 (1). pp. 504-512. ISSN 0094-243X

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Abstract

In rare earth cobaltites, the cobalt ions are present mainly in the diamagnetic low-spin CoIII state at low temperatures. The CoIII ions transform to high-spin Co3+ ions with increase in temperature. At higher temperatures, there is electron-transfer from Co3+ to CoIII ions producing intermediate states. We see spin-state transitions in these cobaltites in the range 250-870 K. At very high temperatures, the cobaltites show evidence for localized itinerant electron transitions. In La1-xSrxCoO3, there is onset of ferromagnetism at x>0.125, at which point there is a structural discontinuity and electrons become itinerant. The composition with x=0.5 is metallic and Tc=230 K. The ferromagnetic component in La1-xSrxCoO3, increases with x in the range 0.125-0.50. In LaCo1-xFexO3, the iron ions are always present in the high-spin state and the d-electrons get more localized with increase in x. Effect of substitution by ions like Th4+ and Ni3+ in LaCoO3 have also been examined. Catalytic properties of rare earth cobaltites appear to be related to the spin state equilibria.

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Deposited On:18 Oct 2010 06:23
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