Dielectric Relaxations in Bi_2O_3-Nb_2O_5-NiO Cubic Pyrochlores

摘要

Dielectric properties of pyrochlores compositions from Bi_2O_3-Nb_2O_5-NiO system were analyzed. The dielectric properties are dominated with a low-temperature relaxation that is typical for Bi-pyrochlores. A vast pyrochlore homogeneity range that exists in this system allowed to correlate characteristics of the observed relaxations with a compositional variations within the A_2O'- and B_2O_6 pyrochlore sublattice. It was possible to make a distinction between different influences of the two sublattices, which can be satisfactorily described by the existing relaxation model for Bi_(3/2)ZnNb_(3/2)O_7. A new relaxor-like room temperature relaxation was found for Bi_(1.6)Ni_(0.57)Nb_(1.43)O_(6.55).