Effect of Isovalent B-Site Doping on Structural and Electrical Properties of Bismuth-Sodium-Titanate

Samples exhibiting substitution of Titanium in Bismuth-Sodium-Titanate (BNT) by isovalent Zirconium, Tin and Germanium (Bi0.5Na0.5Ti(1-x)DxO3 with D = Zr, Ge and Sn and x = 0.0025; 0.0050; 0.01; 0.02; 0.04; 0.08) were investigated with respect to microstructure, relative permittivity, loss factor and polarization. The substituents differ in mass, ionic radius and d-electron configuration. The shift of transitions observed in plots of permittivity and loss factor vs. temperature indicate the influence of the ionic radius. The occurrence of a pinched hysteresis loop at ambient temperature in the Sn-doped samples and the absence of any pinching in the hysteresis loops of Zr-and Ge-doped samples give rise to the assumption that this feature of polarization is connected to the ionic radius combined with the d10 electron configuration of Sn4+.