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Vibrational spectroscopic studies of the ferroelectric $LiRbSO_4$

Chary, Raghunatha B and Bhat, HL and Chandrasekhar, P and Narayanan, PS (1986) Vibrational spectroscopic studies of the ferroelectric $LiRbSO_4$. In: Journal of Raman Spectroscopy, 17 (1). pp. 59-63.

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Abstract

Lithium rubidium sulphate, $LiRbSO_4$ (LRS), undergoes a sequence of four phase transitions at 166, 185, 202 and 204C. The phase between 202 and 204C is incommensurate. Polarized phonon Raman spectra in the frequency region of $50-1200 {cm}^-1$ are presented to identify the external and internal vibrational modes at room temperature. The internal mode frequencies of the sulphate ions are presented in the temperature region from -150 to 230C covering all the phase transitions. The total integrated areas of the 1, 2 and 4 modes show an anomalous increase across the phase transitions. The frequencies of the symmetric stretching ( 1) and symmetric bending ( 2) modes do not show any changes at the phase transitions, but the width of the 2 mode shows changes across the phase transitions. A small increase in the linewidth of the 2 mode observed in the incommensurate phase is attributed to the influence of the incommensurate modulation wave. A DSC thermogram showed endothermic peaks during heating at all the phase transitions. The IR spectrum recorded at room temperature showed the expected Au and Bu internal modes.

Item Type: Journal Article
Additional Information: The copyright belongs to John Wiley & Sons, Ltd.
Keywords: vibrational spectroscopy;ferroelectric;lithium rubidium sulphate;raman spectra
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 21 Sep 2005
Last Modified: 27 Aug 2008 11:28
URI: http://eprints.iisc.ernet.in/id/eprint/3674

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