4?xZnxO7+δ (x=0–3) oxides]]>

摘要

Abstract Oxygen nonstoichiometry and thermodynamic stability of Zn–doped YBaCo4?xZnxO7+δ oxides were investigated by solid state coulometric titration and EMF-method, respectively. As a result, significant zinc doping was shown to increase the stability of YBaCo4?xZnxO7+δ oxides in oxidizing atmosphere. However enrichment of YBaCo4?xZnxO7+δ oxides by zinc results in increasing their reducibility since the low pO2 stability limit shifts towards higher pO2 values upon doping. Substitution of zinc for cobalt in YBaCo4?xZnxO7+δ oxides was also found to narrow their oxygen homogeneity region. Total conductivity and Seebeck coefficient of YBaCo4?xZnxO7+δ oxides were measured simultaneously using 4-probe dc-method. The defect structure of YBaCo4?xZnxO7+δ oxides was successfully analysed using Kr?ger-Vink approach. The data on oxygen nonstoichiometry, total conductivity and Seebeck coefficient of the thermodynamically stable YBaCo4?xZnxO7+δ (x=0, 1) oxides were found to be quite consistent with the proposed model of their defect structure. Highlights ? Oxygen content and thermodynamic stability of YBaCo4?xZnxO7+δ oxides was studied. ? Zn-doping narrows oxygen homogeneity range. ? Zn-doping increases reducibility but improves stability to oxidation.