Open AccessINFLUENCE OF POLYTYPY ON PHASE TRANSITIONS IN TlGaSe2 CRYSTALS
Author(s) -
A.Ch. Matiyev,
R.T. Uspazhiev
Publication year - 2021
Language(s) - English
Resource type - Conference proceedings
DOI - 10.34708/gstou.conf..2021.76.13.002
Subject(s) - curie temperature , condensed matter physics , ferroelectricity , atmospheric temperature range , polarization (electrochemistry) , materials science , phase (matter) , curie , phase transition , thermodynamics , chemistry , ferromagnetism , physics , optoelectronics , organic chemistry , dielectric
It is shown that, in the C-polytype of TlGaSe2 crystals, the structural PT, which occurs at a temperature of T ~ 108 K, is accompanied by an abrupt change in the value of the parameter c (∆c ~ 0.004 Å). For the 2C-TlGaSe2 polytype, the c (T) dependence shows only one clearly pronounced maximum at the temperature Tc2. Moreover, at temperatures that are T1 ~ 30 K higher and T2~ 5 K below Tc2, the Curie-Weiss law is fulfilled. The absence of a fourfold increase in the parameter from the unit cell for 2C-TlGaSe2 samples in the temperature range T = 100-300 K indicates that spontaneous polarization is the order parameter of the ferroelectric PT