Quantification of thermodynamic properties for vaporisation reactions above solid Ga2O3 and In2O3 by Knudsen Effusion Mass Spectrometry

Even though Ga2O3 and In2O3 are broadly used as semi-conductors, thermodynamic data for their vaporisation reactions exhibit a large spread. Therefore, the behaviour of solid was determined by means Knudsen Effusion Mass Spectrometry (KEMS). were studied in an iridium cell heated over temperature range 1200–1750 K order to identify species present vapour phase, determine partial pressures. We find that M2O (where M = Ga or In) is most abundant gas above oxide, followed MO, accord with tabulated data. Following calculation pressures equilibrium constants, we propose ΔfH298,3rdoGa2Og −68966 ± 7442 Jmol-1 ΔfH298,3rdoIn2Og −22245 964 from 3rd law method. Deviations ΔfH298,3rdoi relative literature KEMS measurements generally within ∼2% relative, can be ascribed use different ionisation cross sections, material, calibrations, well Gibbs energy functions. However, comparison ab initio studies suggests reported this work more accurate than previous studies, given ΔfH298,3rdoInOg 157744 3681 deviates only ∼0.2% theoretical value.