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

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.