Tuning of phonon anharmonicity in pyrochlore titanates: temperature-dependent Raman studies of Sm2Ti2-xZrxO7 (x=0, 1/2, 3/4, and 2)and stuffed spin-ice Ho2+xTi2-xO7-x/2 (x=0, 1/3, and 2/3)

Sah, Surajit and Prusty, Sudakshina and Singh, Surjeet and Suryanarayanan, R and Revcolevschi, A and Sood, AK (2012) Tuning of phonon anharmonicity in pyrochlore titanates: temperature-dependent Raman studies of Sm2Ti2-xZrxO7 (x=0, 1/2, 3/4, and 2)and stuffed spin-ice Ho2+xTi2-xO7-x/2 (x=0, 1/3, and 2/3). In: Journal of Raman Spectroscopy, 43 (4). pp. 549-555.

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Abstract

Anomalous temperature dependence of Raman phonon wavenumbers attributed to phononphonon anharmonic interactions has been studied in two different families of pyrochlore titanates. We bring out the role of the ionic size of titanium and the inherent vacancies of pyrochlore in these anomalies by studying the effect of replacement of Ti4?+ by Zr4?+ in Sm2Ti2O7 and by stuffing Ho3?+ in place of Ti4?+ in Ho2Ti2O7 with appropriate oxygen stoichiometry. Our results show that an increase in the concentration of the larger ion, i.e. Zr4?+ or Ho3?+, reduces the phonon anomalies, thus implying a decrease in the phononphonon anharmonic interactions. In addition, we find signatures of coupling between a phonon and crystal field transition in Sm2Ti2O7, manifested as an unusual increase in the phonon intensity with increasing temperature. Copyright (c) 2011 John Wiley & Sons, Ltd.

Item Type:	Journal Article
Publication:	Journal of Raman Spectroscopy
Publisher:	John Wiley and Sons
Additional Information:	Copyright of this article is belongs to John Wiley and Sons.
Keywords:	geometrically frustrated pyrochlore;phonon anharmonicity; Raman spectroscopy;crystal field transition
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	14 Aug 2012 05:06
Last Modified:	14 Aug 2012 05:12
URI:	http://eprints.iisc.ac.in/id/eprint/44489

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