Sodium pyrovanadate

Study on Thermodynamic Properties of Sodium Pyrovanadate at High Temperature

Pei, Guishang, et al. Calphad, 2020, 70, 101802.

Thermodynamic properties of sodium pyrovanadate (Na4V2O7) powder were studied at high temperature (298.15-873 K), including phase transition temperature, phase transition heat, high temperature heat capacity and other thermodynamic functions.
Evaluation methods and results
· The Na4V2O7 powder was synthesized through a solid-state reaction, and its thermodynamic properties were assessed using MHTC 96 line and differential scanning calorimetry (DSC).
· The heats of phase transformation were measured via DSC, revealing ΔH1 = 1.03±0.01 kJ/mol for the transition from α-Na4V2O7 to β-Na4V2O7 at 696 K, and ΔH2 = 31.35 ±0.31 kJ/mol for melting at 931 K.
· The high-temperature heat capacity of Na4V2O7 was determined using DSC and the drop method over a temperature range of 298.15 K to 873 K, and was modeled as: Cp = 314.62 + 0.05T - 5494390T^-2 J·mol^-1·K^-1 (for 298.15-873 K).
· The temperature-dependent high-temperature heat capacity was subsequently utilized to calculate changes in enthalpy, entropy, and Gibbs free energy.