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 (ѓЙ =
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„ѓ by the value ѓўc . (0.002Ѓc0.003) A is observed at temperatures Tp =
145Ѓc147 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.
