Determination of Gibbs Free Energy of Formation of MnV2O4 Solid Solution at 1823 K (1550 A degrees C)

Abstract

The Gibbs free energy of formation of MnV2O4 solid solution saturated with either MnO or V2O3 was experimentally determined at 1823 K (1550 A degrees C) by employing a chemical equilibrium technique. The MnV2O4 solid solution mixed with MnO or V2O3 was brought to equilibrium with either liquid Fe or liquid Cu to measure equilibrium compositions of the liquid metal. Using the available thermodynamic parameters such as Wagner's interaction parameter for liquid Fe or Gibbs free energy of liquid solution composed of Cu-Mn-V-O, the Gibbs free energy of formation of the MnV2O4 solid solution from constituent oxides (MnO and V2O3) was then determined to be: MnO(s) + V2O3(s) = MnV2O4(MnO-satd.): = -31.4 +/- A 2 (kJ/mol); MnO(s) + V2O3(s) = MnV2O4(V2O3-satd.): = -37.8 +/- A 2 (kJ/mol). The values were independent of the oxygen partial pressure within the range from 2.0 x 10(-12) to 6.3 x 10(-11), employed in the current study.