2016 Volume 57 Issue 1 Pages 46-51
The isobaric heat capacities, Cp,m°, for BaMoO4 at 2–300 K were measured by the relaxation method. The third law entropy, Sm°, was determined via the Debye-Einstein function into which the Debye temperature, ΘD, as physico-chemical constant and a thermal expansion term were incorporated. ΘD was determined from Cp,m° at very low temperatures. The obtained thermodynamic properties were: Sm° (BaMoO4(cr), 298.15 K)/J K−1 mol−1 = 152.69 ± 1.53; ΘD(BaMoO4(cr))/K = 295 ± 3. The phase stability of BaMoO4 was discussed on the basis of its standard Gibbs energy of formation, Δ fGm°. It was derived by combining Sm° determined in this study with the reference data of the standard enthalpy of formation, Δ fHm°. The thermodynamic properties obtained in the present study can be used for evaluating the hierarchy for formation of the yellow phase related-substances in nuclear waste glasses.