Microstructural and impedance study of nanocrystalline lanthana-doped scandia-stabilized zirconia

Lanthana-doped (0-4 mol%) scandiastabilized zirconia was synthesized by chemical co-precipitation from an aqueous solution of appropriate salts. Microstructural characterization, phase identification, and conductivities were determined by X-ray diffraction (XRD), scanning (SEM), transmission electron microscopy (TEM), and complex impedance analysis. The crystallite size of the as-precipitated compound, determined from XRD peak broadening and verified by TEM, varied between 20 and 30 nm. SEM studies revealed that the sintered microstructure was dense and uniform. Complex impedance analysis allowed determination of frequency and temperature dependence of both alternating (AC) and direct current (DC) conductivities of the material. The results indicated a gradual decrease in impedance of both grain and grain boundary with increase in lanthana doping. Temperature dependence studies of both AC and DC conductivities shows that the maximum conductivity is obtained in 3 mol% lanthana-doped compound, which incidentally records the highest density, too