Influence of lone pair on structural and electrical properties of Sb substituted Bismuth layered SrBi2Nb2O9 ceramics

Antimony (Sb) substituted Strontium Bismuth Niobate ceramics with chemical formula SrBi2-xSbx Nb2O9 (SBSN) have been prepared through conventional solid state reaction method with varying Sb content in the range (x = 0.0 to 0.5). Limited solubility of Sb content in SBN ceramics were revealed through X-ray diffraction studies which indicates secondary phases of Sb2O3 in prepared ceramics for Sb content x > 0.2. Formation of single phase with orthorhombic structure were confirmed for compositions having x = 0.0 to 0.2. Increase in c-axis of lattice crystal are analyzed and correlated to the ionic structure and existence of lone pair in Sb. Dielectric properties of all SBSN ceramics compositions are studied as a function of temperature over the frequency range of 100 Hz-1 MHz. Increase in Sb incorporation shows insignificant shift in Ferroelectric to Paraelectric Phase transition Temperature in SBSN ceramics. Sb substitution results in the increase in ferroelectricity (2Pr = 15.4 μC/cm2) and poiezoelectric coefficient (d33 = 20 pC/N) for composition having x = 0.1 in SBSN ceramic. Sb substitution results in increase of piezoelectric coefficients (d33) whereas piezoelectric charge coefficient values for composition SrSb0.1Bi1.9Nb2O9 was found to be comparable to that of PZT at room temperature. Existence of lone pair of electron in Antimony were correlated with high piezoelectric coefficient in SBSN ceramics.