https://doi.org/10.1007/s100510050430
Investigations on the soft-mode mechanism of the ferroelectric phase transition in K2ZnI4
Fachrichtung 10.2 Experimentalphysik, Universität des
Saarlandes, 66041 Saarbrücken, Germany
Corresponding author: a mijoc@stud.uni-sb.de
Received:
7
April
1998
Revised:
5
June
1998
Accepted:
16
June
1998
Published online: 15 September 1998
Dielectric and Raman spectroscopic measurements have been
performed to investigate the ferroelectric phase transition in
K2ZnI4. 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 
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/Bg-symmetry. The phase transition mechanism in
K2ZnI4 can be classified as partially order-disorder and partially
displacive, confirming former structural results. It resembles
strongly that of monoclinic K2ZnI4.
PACS: 77.80.Bh – Phase transitions and Curie point / 77.22.Gm – Dielectric loss and relaxation / 78.30.-j – Infrared and Raman spectra
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1998
