Thermal expansion and thermodynamic properties of M′-YbTaO4 ceramics

Double pyrovanadates CaMgV2O7: Formation mechanism, phase structure, and thermodynamic properties

“…The heat capacity of CaMgV 2 O 7 at 298.15 K is 200 J mol K −1 based on a reasonable estimation, considering that both the low-and high-temperature calculated values and entropy at 298.15 K are equal to 198 J mol K −1 . The temperature range of measurement in this study was 15-250 K, and the contribution of the formation entropy below 15 K (29 J mol K −1 ) was considered using the same method proposed by Guskov et al 32,33 Moreover, the enthalpy of formation is a critical important thermodynamic for the calculation of the Gibbs free energy of matter at high temperatures, Neumann-Kopp rules are typically used to estimate the unavailable entropy and heat capacity values. 34 Due to the insufficient experimental data, the enthalpy of formation was analogously estimated from the sum of the enthalpy of formation of stoichiometric amounts of Ca 2 V 2 O 7 and Mg 2 V 2 O 7 .…”