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

J. 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 compositionBa0.5Sr0.5Fe0.8M0.2O3-δ (M = Ni, Cu, Zn) were synthesized bythemodified Pechini method, and their structure andmicrostructurewere 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 comparedwith those of Co containing Ba0.5Sr0.5Fe0.8Co0.2O3-δ perovskite.The highest electrical conductivity was obtained forBa0.5Sr0.5Fe0.8Cu0.2O3-δ, with values of 47.6 Scm−1 at 544 °C.This same composition also exhibits the highest oxygen vacanciesconcentration: 3-δ = 2.61 at room temperature. In contrast,the Ba0.5Sr0.5Fe0.8Zn0.2O3-δ, showed lower electrical conductivitysuggesting that the Zn+2 ions block electron transport. Cofreeperovskites seem to be stable at high temperatures for longterm periods. However, these compounds suffered degradationat room temperature in samples stored in air.