A comparative study of high temperature properties of cobalt-free perovskites

JUAN F. BASBUS; F. PRADO; A. CANEIRO; L. MOGNI

JOURNAL OF ELECTROCERAMICS

SPRINGER

Lugar: Berlin; Año: 2014 vol. 32 p. 311 - 318

1385-3449

Co-free perovskites with chemical composition Ba0.5Sr0.5Fe0.8M0.2O3-δ (M = Ni, Cu, Zn) were synthesized by themodified Pechini method, and their structure andmicrostructure were characterized by XRD and SEM. Oxygen content, electrical resistivity and Thermal Expansion Coefficient (TEC) were evaluated in air between room temperature and 900 °C.The high-temperature properties of these perovskites were compared with those of Co containing Ba0.5Sr0.5Fe0.8Co0.2O3-δ pevrovskite. The highest electrical conductivity was obtained for Ba0.5Sr0.5Fe0.8Cu0.2O3-δ, with values of 47.6 Scm−1 at 544 °C. This same composition also exhibits the highest oxygen vacancies concentration: 3-δ = 2.61 at room temperature. In contrast, the Ba0.5Sr0.5Fe0.8Zn0.2O3-δ, showed lower electrical conductivity suggesting that the Zn+2 ions block electron transport. Co-free perovskites seem to be stable at high temperatures for longterm periods. However, these compounds suffered degradation at room temperature in samples stored in air