Gravity-induced structural deformation for enhanced ferroelectric performance in lead-free piezoelectric ceramics

The effect of gravity-driven sintering on the enhancement of ferroelectricity in lead-free piezoelectric ceramics was investigated. The (Ba0.7Sr0.3)TiO3 ceramics were fabricated using normal sintering and gravity-driven sintering. The ferroelectricity was investigated from polarization-electric field hysteresis loops, revealing that gravity-driven sintering led to an enhancement of ferroelectricity. Temperature-dependence of dielectric constant exhibited a shift of Curie temperature and improved maximum dielectric constant in the gravity-driven sintered ceramics. The crystal structure was investigated by structure refinement, resulting the tetragonal structure with expanded lattice constants and tetragonality in the gravity-driven sintered ceramics. The electron density distribution is indicated the stronger covalent bonding between Ti and O ions in the gravity-driven sintered ceramics due to lattice deformation by mechanical stress. The covalent bonding enhanced at 300 K was linked to the improved ferroelectricity. The structural changes induced by gravity-driven sintering played a crucial role in enhancing ferroelectricity, providing insights for the development of next-generation materials.