Crystal structure and thermodynamic properties of post-spinel-type CaV2O4 at high temperatures (298.15–1373 K)

We conducted an analysis of the crystal structure and thermodynamic properties of CaV₂O₄ synthesized through high-temperature solid-state calcination under elevated temperature conditions. The XRD analysis indicated that CaV₂O₄ crystallizes in an orthorhombic structure, characterized by unit cell parameters a = 9.21311(10) Å, b = 3.008421(35) Å, c = 10.68206(12) Å, and α = β = γ = 90°. The enthalpy of formation and entropy of CaV₂O₄ at 298.15 K are −1890.56 ± 5.84 kJ/mol J·mol⁻¹ and 129.62 ± 1.09 J·mol⁻¹ K⁻¹, respectively. The heat capacity of CaV₂O₄ at 573–1373 K was determined using drop calorimetry, yielding the expression C_p = 165.7748 + 3.2353 × 10⁻²T - 2.64268 × 10⁶T⁻² (J·mol⁻¹·K⁻¹). Additional thermodynamic data for CaV₂O₄ were derived using the C_p,m expression at elevated temperatures.