Mass Spectrometric Investigation of Thermodynamic Properties of CaSiO3 Wollastonite

The evaporation of wollastoniteWollastonite in the temperatureTemperature range of 1751–2087 K was studied using the Knudsen effusion mass spectrometric method. The vapor species typical of simple oxides, as well as the CaSiO3 gaseous oxide have been identified in the gas phase over wollastoniteWollastonite. The partial pressures of vapor species of the gas phase over wollastoniteWollastonite were determined for the first time. The oxide activities, as well as the enthalpy and entropy of the formation of wollastoniteWollastonite from simple oxides, were determined on the basis of their data. These values were equal to –38.92 ± 0.52 kJ/mol and 2.33 ± 0.29 J/(mol × K), respectively, and the CaSiO3 melting enthalpy at 1818 ± 7 K was calculated to 27.64 ± 0.57 kJ/mol.