On features of crystal structure of semiconductor-ferroelectric Ag₃AsS₃

Abstract

The temperature dependences of the unit cell parameters a(T) and c(T) of Ag₃AsS₃ were measured by the X-ray dilatometry method with high precision within the temperature range 100 to 300 K in the dark mode and under laser irradiation (λ = 532 nm). It was found that the parameter c increases almost linear with decreasing the temperature from 300 down to 100 K for samples in the dark. At the same time, for samples that were exposed during cooling to laser irradiation, the increase of the parameter с by the value ∆c ≈ (0.002…0.003) Å is observed at temperatures Tp = 145…147 K. This leap is typical for systems in which a phase transition of the first order occurs. Furthermore, there were investigated temperature dependences of the integral relative intensity I(T) of main structural maxima of Ag₃AsS₃ both in the dark mode and under laser irradiation. It was established the character of the dependence I(T) for these reflexes was changed significantly by laser irradiation.