Phase transitions and metastable states in TIGaSe2

The results of measurements of the dielectric constant of TlGaSe2 in temperature range of successive phase transitions are presented. An anomaly in the temperature dependence of the real part of dielectric constant in TlGaSe2 has been observed at about 242K in addition to anomalies at 115, 108, and also near 65K as reported in previous publications. The presence of temperature hysteresis effects in temperature interval between 115 and 242K allowed making a conclusion about possible existence of an incommensurate phase in the mentioned temperature range. A model of succession of the structural phase transitions in TlGaSe2 has been suggested.