Structural phase transitions in Fe3+ -doped ferroelectric TlGaSe2 crystal

This paper presents the results of dielectric constant and Electron Paramagnetic Resonance (EPR) investigations of Fe3+-doped TlGaSe2 single crystals in the temperature range of 15-300 K. The influence of Fe impurities on dielectric properties and phase transitions of TlGaSe2 crystal has been studied. The results were considered in comparison with earlier observed results from pure TlGaSe2 compounds. We observed the considerable decrease of the dielectric constant as well as the change of the shape of the temperature dependence of the dielectric constant in doped crystals. Some certain significant changes of EPR spectra, which are associated with a strong splitting and appearance of additional resonance lines, were observed at the temperatures below 110 K. Such transformations are considered as the result of non-equivalent displacements of different groups of Tl atoms during the structural phase transitions.