Effect of La₂O₃ substitutions on structure and dielectric properties of Bi₂O₃–ZnO–Nb₂O₅-based pyrochlore ceramics

The effect of La₂O₃ substitutions on structure and dielectric properties of Bi₂O₃ –ZnO–Nb₂O₅-based ceramics was investigated. Bi_1.5-xLa_xZn_0.5(Zn_0.5Nb_1.5)O₇ samples were prepared by conventional ceramic processing technology. The crystal structure of the Bi_1.5Zn_0.5(Zn_0.5Nb_1.5)O₇ sample was characterized as a pure cubic pyrochlore. With a lower amount of La₂O₃ substitution, the crystal structures were still cubic pyrochlore. Superlattice x-ray diffraction line was identified for some compositions. With the increasing amount of La₂O₃ substitution, the crystal structure gradually transformed from pure cubic pyrochlore to LaNbO₄ phase. The dielectric properties regularly changed with the structure change. The structure-properties relations of the ceramics are discussed.