X-Ray and Thermographic Study of the alpha yields beta Phase Transition in Ag2S.

It is shown that the phase transition occurring in Ag//2S in the 174-185 degree C temperature range is preceded by a pretransition temperature range (130-170 degree C) characterized by distortion of the alpha -phase lattice. The parameters which make it possible to quantitatively describe the temperature dependence of the phase mass ratio during the phase transition are determined. The thermal expansion coefficients of the alpha - and beta -phase lattices are calculated. The heat, entropy and energy of activation of the alpha yields beta transition are determined, and the thermal conductivity coefficient in the transition range is calculated.