Oxygen nonstoichiometry of LnMnO3− (Ln=La, Pr, Nd, Sm and Y)

The oxygen nonstoichiometry of LnMnO3−δ (Ln=La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb and Y), which is in equilibrium with its decomposition products of Ln2O3 and MnO at the phase boundary, was determined at 1273 K. Temperature dependence of the oxygen defect δ was determined for LnMnO3−δ, with Ln=La, Pr, Nd, Sm and Y in the temperature range from 1073 to 1373 K. The dependence of concentration of oxygen defect for LnMnO3−δ at Ln=Nd and Sm on the oxygen partial pressure at 1273 K was well explained by the simple cluster model. From the temperature dependence of the equilibrium constant for the formation of oxygen defect, the standard enthalpy and entropy changes of defect formation were estimated for LnMnO3−δ with Ln=La, Pr, Nd, Sm and Y.