The effect of dopants on the dielectric properties of Ba(B'Ta-1/2(1/2))O-3 (B'=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Yb, and In) microwave ceramics

Abstract

Low-loss dielectric ceramics based on Ba(B'Ta-1/2(1/2))O-3 (B'=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Yb, and In) complex perovskites have been prepared by the solid-state ceramic route. The dielectric properties (epsilon(r), Q(u), and tau(f)) of the ceramics have been measured in the frequency range 4-6 GHz by the resonance method. The resonators have a relatively high dielectric constant and high quality factor. Most of the compounds have a low coefficient of temperature variation of the resonant frequencies. The microwave dielectric properties have been improved by the addition of dopants and by solid solution formation. The solid solution Ba[(Y1-xPrx)(1/2)Ta-1/2]O-3 has x=0.15, with epsilon(r)=33.2, Q(u) x f=51,500 GHz, and tau(f)approximate to 0. The microwave dielectric properties of Ba(B'Ta-1/2(1/2))O-3 ceramics are found to depend on the tolerance factor (t), ionic radius, and ionization energy.