Synthesis, Impedance and Dielectric Studies of Double Doped Strontium Bismuth Niobate Ferroelectric Ceramics

Strontium bismuth niobate (SrBi2Nb2O9 (SBN), K0.025Sr0.95Gd0.025Bi2Nb2O9 (KSGBN1), K0.05Sr0.9Gd0.05Bi2Nb2O9 (KSGBN2) and K0.1Sr0.8Gd0.1Bi2Nb2O9 (KSGBN3)) ceramics were prepared by two stage solid state reaction method. Calcination was done at 850(o)C for 4 h. Structural property of calcined samples was studied by powder X-ray diffraction (XRD) technique at room temperature. XRD patterns of the samples so obtained matched well with the reported data (ICSD #82280). Lattice parameters of the samples were calculated using POWD software. Pellets of 10 mm diameter and similar to 1 mm thickness were prepared using uniaxial hydraulic press at 10 MPa pressure. These pellets were finally sintered at 950(o)C for 4 h. The surface morphology of the samples was studied with scanning electron microscope (SEM). The density of the sintered ceramics was measured by Archimedes principle. Impedance variation with temperature was studied for SBN, KSGBN1, KSGBN2 and KSGBN3 in the frequency range of 100 Hz to 1 MHz. The temperature dependence of dielectric properties of SBN, KSGBN1, KSGBN2 and KSGBN3 were obtained at some set frequencies in the range of 100 Hz to 2 MHz using HP 4192A impedance analyzer. The data obtained was analyzed based on change in tolerance factor, anisotropy and strain due to the presence of doped impurities. Interesting conclusions arrived at have been presented.