Understanding microwave dielectric properties of Pb-based complex perovskite ceramics via bond valence

Correlations between microwave dielectric properties and the dielectric polarizabilities related to the bond valences of A- and B-site ions in Pb-based complex perovskite ceramics have been investigated. With the decrease of A-site bond valence, the dielectric constants were higher than those obtained from the dielectric additivity rule due to the rattling behavior of A-site ions. The temperature coefficient of the resonant frequency (TCF) depended strongly on the bond valences of the A- and B-sites, as well as the tolerance factor (t) in the perovskite structure. In the tilted region (t<1.0), the tilting of the oxygen octahedra increased and the TCF decreased because of the increasing bond valence of the B-site. Also, the dependence of TCF on the bond valence of the A-site was similar to its dependence on the tolerance factor (t).