Oxygen nonstoichiometry, defect structure and related properties of LaNi0.6Fe0.4O3−δ

Abstract

Experimental results on oxygen nonstoichiometry (δ), thermal and chemical expansion (ΔL/L₀), total electrical conductivity (σ) and Seebeck coefficient (Q) as functions of the oxygen partial pressure (p_O2) and temperature for LaNi_0.6Fe_0.4O_3−δ are presented. The defect structure model of LaNi_0.6Fe_0.4O_3−δ based on the localized nature of the electronic defects was proposed and successfully verified using the measured δ = f(p_O2, T) dependences. On the basis of the model proposed the concentrations of the point defects were calculated as functions of the T and p_O2. These concentrations were then employed in the model of chemical expansion and that of Seebeck coefficient. It was shown that both models coincide completely with the corresponding experimental data. The chemical expansion coefficients (β_c) and mobilities of the charge carriers (electrons and holes) as functions of T and p_O2 were calculated as a result.