Giant dielectric response in (Nb plus Zn) co-doped strontium titanate ceramics tailored by atmosphere

Effects of sintering and annealing atmosphere on the defect structures and the dielectric behaviors of (Nb + Zn) co-doped SrTiO3 ceramics are systematically investigated. Giant permittivity (-50,100), low dielectric loss (similar to 0.04) and wide temperature (25-330 degrees C)/frequency (20-10(5) Hz) stabilities are achieved in the N-2 sintering ceramics. Further investigations indicate massive defects and defect clusters are involved, contributing to the giant permittivity. The associated defects not only restrain the ionization of oxygen vacancy, but also localize the motions of oxygen vacancy and electron, resulting in the low dielectric loss and the suppressed relaxation peaks. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.