Investigation of site selectivity of lanthanum in SrBi4Ti4O15 ceramic by structural, dielectric, ferroelectric and conduction behavior

Abstract

This manuscript reports the structural and electrical properties of Lanthanum substituted strontium bismuth titanate with general formula SrBi4−xLaxTi4O15 (where 0 ≤ x ≤ 0.25), prepared by solid-state reaction route. X-ray diffraction study shows a single phase orthorhombic structure in all the compositions. It was also observed that the lattice parameter increases up to x = 0.15 and then decreases with further La content. The Raman spectra shows the distribution of lanthanum into the perovskite layers and (Bi2O2)2+ layers of SrBi4Ti4O15 ceramic. The temperature dependent dielectric study reveals that the transition temperature and maximum dielectric constant decreases with La content. The broadening of the phase transition was observed with La substitution due to the decrease in octahedral distortion. Impedance analysis confirms the presence of two semicircular arcs in doped samples, suggesting the existence of grain and grain-boundary conduction. The P-E loop study shows that both the remnant polarization (Pr) and the coercive field increases with the increasing La content up to x = 0.15 and thereafter decreases to lower values with further La content. Similar kind of trend is also observed in DC conductivity.