The phase structure, thermodynamic properties, and dissolution behavior of Ca5Mg4V6O24

A Ca5Mg4V6O24 compound was synthesized through solid-state roasting routes under an air atmosphere, and its crystal structure and thermodynamic properties were determined using various methods. The cell parameters of Ca5Mg4V6O24 indicate that it crystallizes in cubic space group Ia3d with the unit cell parameters a = 12.442 +/- 0.001 angstrom. X-ray photoelectron spectroscopy also confirmed that the vanadium element in the Ca5Mg4V6O24 sample is present in the +5 state. The melting of Ca5Mg4V6O24 was detected at 1442 K. The molar heat capacity (374 J mol K-1) and entropy (688.2 J mol K-1) of Ca5Mg4V6O24 at 298.15 K were determined using physical properties measurement system, and simultaneous thermal analyzer for the first time. The solubility of Ca5Mg4V6O24 in water at different temperatures was measured and its dissolution behavior in sulfuric acid and kinetics was experimentally established.