Effect of Porosity on Electrical Properties of Undoped and Lanthanum Doped BaTi0.6Zr0.4O3

In porous media, the porosity introduces inhomogeneity in the bulk, which alters the mechanisms of leakage and breakdown exhibited by the dense analog. The presence of pores in solid dielectrics significantly degrades the electrical characteristics and breakdown strength of the material. Lanthanum doped BaTi0.6Zr0.4O3 composition in Ba1-xLaxTi0.6[1¿5x/12]Zr0.4O3 were prepared by modified chemical route. (COOH)2.2H2O, Ba(NO3)2, ZrOCl2.8H2O and La2O3 are used to precipitate barium oxalate hydrate, lanthanum oxalate hydrate and zirconium oxyhydroxide from its water solution onto the surface of suspended TiO2 particles. The lanthanum doped BaTi0.6Zr0.4O3 composition was found to be cubic by XRD analysis. A gradual shift of 2¿ angles to the higher angle with increasing lanthanum percentage in the BTZ reveals the contraction of perovskite lattice. The frequency dependence of dielectric permittivity and loss tan ¿ of the ceramics has been investigated. It is found that dielectric permittivity (¿r) decreases and loss tan ¿ decreases with increase in lanthanum percentage. Loss tan ¿ increases and dielectric permittivity (¿r) decreases with increase in porosity. Resistivity decreases and current density increases with increase in porosity. Neither of the samples shows semiconductivity, which is believed to be because of titanium vacancy compensation.