The European Physical Journal B

ISSN: 1434-6028 (printed version)
ISSN: 1434-6036 (electronic version)

Table of Contents

Abstract Volume 5 Issue 2 (1998) pp 163-168

Investigations on the soft-mode mechanism of the ferroelectric phase transition in $\mathsf{K_{2}ZnI_{4}}$

M. Jochum (a), H.-G. Unruh

Fachrichtung 10.2 Experimentalphysik, Universität des Saarlandes, 66041 Saarbrücken, Germany

Received: 7 April 1998 / Revised: 5 June 1998 / Accepted: 16 June 1998

Abstract: Dielectric and Raman spectroscopic measurements have been performed to investigate the ferroelectric phase transition in $\rm K_{2}ZnI_{4}$. Single crystals were grown by the zone melting method. The frequency dependence of the dielectric permittivity from 1 MHz to 1 GHz has been studied in a temperature range between 265 and 285 K. A Debye like dielectric dispersion was found, showing a critical slowing down around $T_{c}\approx\rm 272$ K. Polarized Raman spectra have been taken between 220 and 310 K. Two softening modes have been found, one of A- and another one of B/B_g-symmetry. The phase transition mechanism in $\rm K_{2}ZnI_{4}$ can be classified as partially order-disorder and partially displacive, confirming former structural results. It resembles strongly that of monoclinic $\rm K_{2}ZnBr_{4}$.

PACS. 77.80.Bh Phase transitions and Curie point - 77.22.Gm Dielectric loss and relaxation - 78.30.-j Infrared and Raman spectra

(a) email: mijoc@stud.uni-sb.de

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Online publication: September 16, 1998
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