Synthesis and Characterization of Pr_(0.6-x)Nd_xSr_(0.4)FeO_(3-δ) System Compounds

Pr0.6-xNdxSr0.4FeO3-δ(x=0-0.6) samples were synthesized by the citrate-nitrate method. The formation process of the perovskite-type phase and the microstructure of the samples were characterized by XRD, FT-IR, TG-DTA, and SEM. The results revealed that all the samples calcined at 1200℃for 2h were single-phase solid solutions with cubic symmetry. The electrical conductivity of sintered ceramics at 450-800℃were measured by four-probe technique. The results show that the specimens with single rare earth and the compounds with Pr or Nd as leading element at A-site have excellent electrical conductivity, the data are over 150S·cm-1,clearly higher than that of two-rare earths specimens. The reason of decreasing electrical conductivity for 0.2≤x≤0.4 is correlated with lower relative density at the same sintering conditions. The maximum value of electrical conductivity for all samples occurred at about 600-700℃, and the electrical conductivity certified that the hopping of small polaron is the dominating mechanism below 650℃.