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Optical studies on the orthorhombic-cubic transitions for $KClO_4$, $RbClO_4$ and $CsClO_4$

Raghurama, G and Al-Dhahir, TA and Bhat, HL (1987) Optical studies on the orthorhombic-cubic transitions for $KClO_4$, $RbClO_4$ and $CsClO_4$. In: Journal of Physics C: Solid State Physics, 20 (28). 4505-11.

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An optical investigation of the high-temp. structural transitions in gel-grown single crystals of $KClO_4$, $RbClO_4$ and $CsClO_4$ is reported. These crystals undergo transitions from the room-temp. Pnma phase to a cubic Fm3m phase at $T_c$ values of $306^0C$, $281^0C$, and $222^0C$, respectively. The birefringence $\Delta n$ falls abruptly to zero at $T_c$, as is expected in a 1st-order transition. The phase transition was also studied by measuring the intensity of light transmitted by the sample placed between crossed Nicol prisms. The results do not suggest the coexistence of phases above $T_c$. Microscopy examination of the samples at transition reveals that on cooling from the high-temp. phase the crystals have a tendency to form multidomains, with differing orientations, in the orthorhombic phase. This suggests that the phase transition is ferroelastic of m3mFmmm type and also explains the mismatch between the results of the heating and cooling runs.

Item Type: Journal Article
Publication: Journal of Physics C: Solid State Physics
Publisher: Institute of Physics
Additional Information: Copyright of this article belongs to Institute of Physics
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 17 Mar 2008
Last Modified: 19 Sep 2010 04:43
URI: http://eprints.iisc.ac.in/id/eprint/13241

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