Effect of donor dopants cerium and tungsten on the dielectric and electrical properties of high Curie point ferroelectric strontium niobate

The perovskite-like layered structure (PLS) A2B2O7 compound Sr2Nb2O7 was doped with donor dopants CeO2 and WO3 to explore their doping effect on its A and B site, respectively. The doped ceramics were prepared by Spark Plasma Sintering. For Ce doping on the A site, single phase was maintained up to 5 mol% Ce (x=0.05 in (Sr1−xCex)2Nb2O7). For W doping on the B site, single phase was maintained at 2.5 mol% W (x=0.025 in Sr2(WxNb1−x)2O7). The cerium and tungsten doping both inhibited grain growth and changed the grain morphology, leading to less anisotropic grains. The Curie point Tc was obtained by measuring the temperature dependence of the dielectric constant and it was found to reduce for both Ce and W doped SNO. The W doped ceramics showed a diffuse ferroelectric phase transition at the Curie point. The DC resistivity of tungsten and cerium doped SNO increased compared to undoped SNO at temperatures below 700 °C. These results showed that both Ce and W had a strong influence on the dielectric and electrical properties of the Sr2Nb2O7 ceramics.