Dielectric properties of lanthanum substituted barium titanate microwave ceramics

In this study, we report the high dielectric constant lanthanum substituted barium titanate ceramic material for its possible applications at microwave frequencies. The microwave dielectric characterization of Ba6-3xLa8+2xTi18O54 solid solutions with 0.0 <= x <= 0.7 prepared by conventional mixed oxide route method has been carried out. The lattice parameters were obtained from the X-ray diffraction patterns. It was observed that lattice parameters increased with respect to an increase in the 'La' content. The crystal symmetry investigated was orthorhombic with space group of Pbam. From the evaluation of microwave dielectric properties of lanthanum doped barium titanate ceramics, it was observed that a maximum value of dielectric constant (epsilon')=157 and a minimum tangent loss (tan delta)=0.0572 was obtained. The minimum value of a.c. conductivity (sigma(a.c)) was observed to be 1.76e-07 S/m. (c) 2006 Elsevier B.V. All rights reserved.