Mg₂V₂O₇ is the most promising candidate for low-temperature co-fired ceramic (LTCC) multilayer devices. Selecting the appropriate precursors strongly requires reliable thermodynamic properties to be defined accurately. In this study, the structural parameters of the Mg₂V₂O₇ at ambient temperature indicate that it is crystallized in space group of P2₁/c. Notably, Mg₂V₂O₇ has low lattice thermal conductivity (k_L) of 4.77, 5.12, and 4.52 W/mK, along the a, b, and c axes, respectively, which originates from the large phonon scattering rate and low phonon group velocity. The α-Mg₂V₂O₇↔β-Mg₂V₂O₇ and β-Mg₂V₂O₇↔γ-Mg₂V₂O₇ polymorphic transitions occur at 743 ℃ and 908 ℃ with enthalpy change of 1.82±0.04 kJ/mol and 1.51±0.04 kJ/mol, respectively. The endothermic effect at 1083 ℃ with an enthalpy change of 26.54±0.26 kJ/mol is related to the congruent melting of γ-Mg₂V₂O₇. In addition, the molar heat capacity of Mg₂V₂O₇ was measured utilizing drop calorimetry at high temperatures. The measured thermodynamic properties were then applied to select precursors for preparing Mg₂V₂O₇ via a solid-state reaction, indicating that the V₂O₅ and Mg(OH)₂ precursors are strongly recommended due to their thermodynamic superiority.

As a promising anode material for magnesium ion rechargeable batteries, magnesium metavanadate (MgV₂O₆) has attracted considerable research interest in recent years. A MgV₂O₆ sample was synthesized via a facile solid-state reaction by multistep-firing stoichiometric mixtures of MgO and V₂O₅ powder under an air atmosphere. The solid-state phase transition from α-MgV₂O₆ to β-MgV₂O₆ occurred at 841 K and the enthalpy change was 4.37 ± 0.04 kJ/mol. The endothermic effect at 1014 K and the enthalpy change was 26.54 ± 0.26 kJ/mol, which is related to the incongruent melting of β-MgV₂O₆. In situ XRD was performed to investigate phase transition of the as-prepared MgV₂O₆ at high temperatures. The cell parameters obtained by Rietveld refinement indicated that it crystallizes in a monoclinic system with the C2/m space group, and the lattice parameters of a = 9.280 Å, b = 3.501 Å, c = 6.731 Å, β = 111.76°. The solid-state phase transition from α-MgV₂O₆ to β-MgV₂O₆ was further studied by thermal kinetics, indicating that this process is controlled first by a fibril-like mechanism and then by a spherulitic-type mechanism with an increasing heating rate. Additionally, the enthalpy change of MgV₂O₆ at high temperatures was measured utilizing the drop calorimetry, heat capacity was calculated and given as: Cp = 208.3 + 0.03583T-4809000T⁻² (298 – 923 K) (J mol⁻¹ K⁻¹), the high-temperature heat capacity can be used to calculate Gibbs free energy of MgV₂O₆ at high temperatures.