Enhancement of relaxor properties by Nb doping in Ba0.8Sr0.12Ca0.08TiO3 lead-free ferroelectric ceramics

Niobium-doped barium strontium calcium titanate (BSCTN) ceramics were prepared using a conventional solid-state reaction method. The effects of Nb contents on crystal structure, microstructure, dielectric properties and ferroelectric relaxor behavior of the BSCTN ceramics were investigated. The BSCTN ceramics showed dense microstructures with uniform crystal grains with Nb doping. It was demonstrated that Nb5+ entered the B-site of the perovskite BSCTN ceramic and substituted for Ti4+, which caused the expansion and distortion of crystal lattice of the tetragonal BSCTN ceramic. Doping of Nb resulted in more diffused phase transition and lower Curie temperature of the BSCTN ceramics. The diffuseness degree indicator γ increased until the addition of Nb dopant exceeded 1.5 mol% where a maximum γ of 1.98 was achieved. Among the compositions assayed in this work, the BSCTN ceramics with Nb contents of approximately 1.0–1.5 mol% yielded promising relaxor properties that made them alternative sources for development of environmental friendly lead-free relaxor ferroelectric materials.