Heat capacity and thermodynamic properties of GeSe2 at temperatures from T= (13 to 900) K. Structural phase transition at T = 423 K

The heat capacity of germanium diselenide GeSe2 has been determined by adia batic calorimetry at temperatures from (13 to 900) K. A phase transition no t previously reported gives rise to a sharp lambda-type heat capacity effec t at T = 423 K. The overall estimated enthalpy of transition amounts to 124 0 J.mol(-1) at T = 600 K. The transition could not be detected by high-temp erature powder X-ray diffraction. Values of the molar heat capacity, standa rd molar entropy, standard molar enthalpy, and standard molar Planck functi on of GeSe2 at T = 298.15 and T = 900 K are: [GRAPHICS] (C) 1999 Academic Press.