OXYGEN NONSTOICHIOMETRY OF THE COPPER-SUBSTITUTED LANTHANUM COBALTITE LaCo_(0.9)Cu_(0.1)O_(3-δ)

摘要

Oxygen nonstoichiometry of LaCo_(0.9)Cu_(0.1)O_(3-δ) has been studied as a function of temperature (1123-1473 K) and oxygen pressure (10~(-3) = Po_2, atm =1) by using both thermogravimetry (TG) method and coulometric titration in a solid electrolyte cell. The absolute values of oxygen nonstoichiometry 5 are calculated from the results of the direct reduction of the samples of LaCo_(0.9)Cu_(0.1)O_(3-δ) in a flux of hydrogen in the TG cell. It was established that oxygen nonstoichiometry has a deficient character (positive 5 values). A defect model is proposed for LaCo_(0.9)Cu_(0.1)O_(3-δ).It is being formed when oxygen is removed from the oxide lattice. The equilibrium constants and enthalpy of defects formation were calculated.