y-Radiation Stimulated Structural Transition of Monoclinic TlInS2 to Hexagonal Phase

Abstract

Temperature dependent dielectric function and conductivity, as well as room temperature photoconductivity have been investigated on monoclinic TlInS2 subjected to -radiation in a wide range of radiation doses. The structural changes have been detected by XRD performed after every stage of -irradiation. Frenkel pairs (vacancies and interstitial sulfur atoms) have been assumed to appear in TlInS2 at irradiation doses below 100 Mrad through well-known Klinger’s ‘‘residual charged impurity assisted electrostatic’’ mechanism. These defects eventually lead to the formation of neutral impurity complexes responsible for the observed sharpening of the anomalies in dielectric function and conductivity at the temperature of the well-known ferroelectric phase transition in TlInS2. The last anomalies become smeared out at irradiation doses above 200 Mrad. Finally, the transformation of the monoclinic TlInS2 to the one with hexagonal structure has been witnessed in a thin surface layer at high fluencies (1000– 1500 Mrad) of -radiation.