Dielectric properties and relaxation of Bi-doped (Pb0.75Ba0.25)(Zr0.70Ti0.30)O3 ceramics

The strong influence of bismuth additions to the lead–barium–zirconate–titanate ceramics of Ba/Zr/Ti 25/70/30 composition on grain structure, dielectric properties and dc conductivity is confirmed. The Bi-modified ceramics exhibit classical relaxor ferroelectrics (RF) behaviour similar to the other lead containing perovskites such as lead–lanthanum–zirconate–titanate-type ceramics. Dielectric relaxation typical for the ferroelectric relaxors is observed in the vicinity of diffuse ferroelectric–paraelectric phase transition. Additional anomalies in ε′ε′(T) curves in the low frequency range, present in the paraelectric phase for the undoped ceramics, are eliminated by the Bi admixture which also reduces the dc conductivity by three orders of magnitude. A qualitative explanation of the experimental results is presented in the paper.