Enhanced tetragonality in lead-free piezoelectric (1−x)BaTiO3–xNa1∕2Bi1∕2TiO3 solid solutions where x=0.05–0.40

A structural investigation was carried out on a perovskite-based solid solution of xNa1∕2Bi1∕2TiO3–(1−x)BaTiO3, where x⩽0.40. The crystal structure remains tetragonal, P4mm, for these compositions; however, enhancement of the tetragonality up to 0.9% of the unit cell was observed as a function of doping which is an unusual phenomenon in BaTiO3 based binary solid solutions. Crystallographic details of the structural changes that have occurred because of the doping were obtained by performing Rietveld refinement on neutron powder diffraction data collected at HRPD of the ISIS spallation neutron source. Temperature- and frequency-dependent dielectric data as a function of composition are presented to understand the structure-property relationships in this novel system.