Abstract
Lead free piezoelectric ceramics with the composition(1-x) Sr2Bi4Ti5O18+ x [(K0.41Na0.53Li0.06)(Nb0.89Sb0.06Ta0.05)O-3] (where x = 0, 0.05, 0.10, 0.15 and 0.20) were synthesized using the pre-reacted Sr2Bi4Ti5O18(SBT) and [(K0.41Na0.53Li0.06)(Nb0.89Sb0.06Ta0.05)O-3](KNLNST) powders via solid-state reaction carried out at 1130 degrees C. Based on X-ray diffraction studies it was confirmed that only less than 0.15 mol of KNLST was soluble in the SBT phase. Raman spectra analyses for these samples revealed that A and B site cations from KNLNST perovskite phase were found to occupy A and B site cations of SBT. There was an increase in the grain size with the increase in x and grains with plate-like morphology were seen in these samples when observed through a scanning electron microscope (SEM). The measured values of relative permittivity (rational electric permittivity) (300 at 1 MHz), dielectric loss (0.013 at 1 MHz), and maximum polarization (5.95 mu C/cm(2)) for the samples with the composition x = 0.2 were found to be superior to that of undoped SBT. The decrease in Curie temperature with the increase in x for all the samples under study was confirmed through temperature dependent dielectric measurements.