A Raman study of the temperature-induced low-to-intermediate-spin state transition in LaCoO3

Motin Seikh, Md. ; Sudheendra, L. ; Narayana, Chandrabhas ; Rao, C. N. R. (2004) A Raman study of the temperature-induced low-to-intermediate-spin state transition in LaCoO3 Journal of Molecular Structure, 706 (1-3). pp. 121-126. ISSN 0022-2860

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Official URL: http://linkinghub.elsevier.com/retrieve/pii/S00222...

Related URL: http://dx.doi.org/10.1016/j.molstruc.2004.03.058

Abstract

The effect of the thermally induced spin-state transition on the phonon mode behavior of LaCoO3 has been investigated by using Raman spectroscopy. The number of observed Raman modes is larger than the number predicted by group theory for a rhombohedrally distorted perovskite structure with the space group R3̅c. There is a strong similarity between the Raman spectrum of LaCoO3 and LaMnO3 at ambient conditions due to the Jahn-Teller (J-T) distortion associated with the intermediate-spin (IS) state of Co3+. The J-T distortion splits the external mode associated with La-O vibration into a doublet above the spin-state transition temperature. There is an increase in the anharmonic coupling between the one-phonon states with increase in temperature above the transition temperature, due to the gradual increase in the population of Co3+ in the IS state.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Cobaltate; Spin-state Transition; Intermediate-spin State; Jahn-teller Distortion; Raman Scattering
ID Code:41869
Deposited On:31 May 2011 12:14
Last Modified:31 May 2011 12:14

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