Lattice enthalpies of lanthanide orthoferrites LnFeO3

Abstract

Lattice enthalpies Δ_LH^Ө of lanthanide orthoferrites, LnFeO₃ have been determined by the Born-Haber cycle and compared with those calculated by an empirical equation.  Enthalpies of formation of LnFeO₃ from two different sources have been employed: from oxides (Ln₂O₃, Fe₂O₃), for 12 LnFeO₃, and from elements, for 8 LnFeO₃, but the differences in Δ_LH^Ө are very small. The Born-Haber cycle in both routes results in close values of Δ_LH^Ө to those obtained by the empirical equation of Glasser and Jenkins. A correspondence in dimension and magnitude has been found between the partial derivative of the lattice enthalpies to the molar volumes and an upper limit of the shear moduli of the lanthanide orthoferrites.