Effect of Ta Doping on the Microstructure, Dielectric and Ferroelectric Properties of Sr2Nb2O7 Ceramics

Sr2(TaxNb1-x)2O7 (x = 0.0, 0.1, 0.2, 0.4) (STNO) ceramics were prepared by the conventional solid-state reaction method. The microstructure, dielectric and ferroelectric properties of the samples were investigated. The results show single phase STNO with perovskite-like layered structure and that Ta5+ ion can diffuses into the crystal lattice. The addition of Ta5+ dopant decreases the grain size of the material. The dielectric constant increases with increased x, and the sample with x = 0.2 exhibits enhanced dielectric properties (ϵr ≈ 56, tanδ ≈ 0.01%). The remnant polarization (2Pr) and coercive electric field (2EC) of STNO ceramics increase with increasing Ta content, and reach the maximum value (2Pr = 0.11μC/cm2 and 2EC = 5.75 kV/cm) at x = 0.4. Our results indicate that Ta doping can effectively improve the dielectric and ferroelectric properties of Sr2Nb2O7 ceramics.