INVESTIGATION OF VAPORIZATION THERMODYNAMICS OF SRUO3 BY MEANS OF MASS-SPECTROMETRY

The vaporization properties of SrUO3 have been studied for the first t ime by means of Knudsen effusion mass spectrometry over a temperature range of 1534 to 1917 K. The sample used was a mixture of SrUO3 and 23 wt% UO2. The main vapor species over the mixture were Sr(g), UO2(g) a nd SrO(g) in decreasing order of their partial pressures. The standard enthalpy of formation of SrUO3 was evaluated by using the second law and the third law treatments, in which estimated values of H degrees(T )-H degrees(298.15) and gef(T) were employed on account of absence of published data. The standard enthalpies of the formation of SrMO3 with pseudo-cubic perovskite structure, where M stands for metallic cation s with the valence of four, were also discussed based on the relations hip between the ionic radii of M4+ of the compounds and their enthalpy values. (C) 1997 Elsevier Science B.V.