Enthalpies of Formation of LaMO3 Perovskites (M = Cr, Fe, Co, and Ni)

Abstract

Enthalpies of formation from constituent oxides and elements at 298 K were determined by high-temperature oxide melt solution calorimetry for a group of technologically important perovskites LaMO3 (M = Cr, Fe, Co, and Ni). The enthalpies of formation of LaCrO3 and LaFeO3 from oxides (La2O3 and Cr2O3 or Fe2O3) are –70.06 ± 2.79 kJ/mol and –64.58 ± 2.32 kJ/mol, respectively. The enthalpies of formation of LaCoO3 and LaNiO3 from oxides (La2O3 and CoO or NiO) and O2 are −107.64 ± 1.77 kJ/mol and –57.31 ± 2.55 kJ/mol, respectively. All these data are evaluated and found to be consistent with literature values obtained using other methods. The relative stability among these four perovskites decreases in the order of Cr, Fe, Co, Ni.