Synthesis and Characterization of Perovskite-Type Composite Oxides of La_(0.7-x)Sr_(x)Nd_(0.3)FeO_(3-δ)

Perovskite-type Composite Oxides of La_(0.7-x)Sr_(x)Nd_(0.3)FeO_(3-δ)(x=0.1,0.2,0.3) were synthesized by the auto combustion method with the metal nitrate as oxidizing reagent and glycine as reducing agent.The specific areas of the synthesized powders were measured by nitrogen adsorption method.The formation conditions,crystalline structure and microstructure of the samples were investigated with XRD,TG-DSC,TEM and SEM.The experimental results show that the single Perovskite-type phase was obtained after the powders(calcined) at 900 ℃ for 2 h.The electrical conductivities of the ceramics were determined by four-probe DC method in the temperature range of 450~800 ℃ in air.The specific area of the species decreases and the(particle) size increases with the increase of Sr content,and the crystal system transforms from orthorhombic to cubic gradually.The conduction mechanism is attributable to the adiabatic hopping of small polarons.The(La_(0.5)Sr_(0.2)Nd_(0.3)FeO_(3-δ)) sample sintered at 1 300 ℃ for 2 h shows the highest conductivity.