Influence of Nb2O5 addition on dielectric properties and diffuse phase transition behavior of BaZr0.2Ti0.8O3 ceramics

Nb2O5 doped Ba(Zr0.2Ti0.8)O3 (short as BZT20) ceramics were prepared by a mixed-oxide method using a high-energy planetary ball mill and the influence of Nb2O5 addition on microstructure, dielectric properties and diffuse phase transition behavior of BZT20 ceramics were investigated. It was demonstrated that Nb5+entered the B-site of BZT20 ceramic and substituted for Ti4+, which caused the expansion and distortion of crystal lattice. BZT20 ceramics doped with 0.2 mol% Nb2O5 showed excellent dielectric property and lower diffusivity with εm=37,823 and γ=1.49. We supposed that the increase of dielectric constant and decrease of diffuseness parameter with increasing Nb2O5 content were caused by lattice disorder and unbalancing of cations induced by the substitution of Ti4+ by Nb5+ in the B sites of BZT20 ceramics. The Curie temperature decreased with the increase of Nb2O5 content, which can be attributed to enlarged distortion energy of the Nb doped BZT20 structure. Besides, grain size effect on the dielectric property and diffuse phase transition behavior of Nb2O5 doped BZT20 ceramics was also investigated.