LAUSR

A small amount of Sn4+ content has a great influence in the lowering the Curie temperature (Tc), enhancing the dielectric properties and reducing the piezoelectric performance of (Ba0.85Ca0.15)(SnxZr0.1−xTi0.90)O3 (x = 0, 0.025, 0.05, 0.075, 0.10) ceramics, and this reaction has been systematically studied. The samples were synthesized by using the conventional solid-state route and then sintered at 1450 °C. They were characterized by X-ray diffraction analysis, ac impedance spectroscopy, scanning electron microscopy, energy dispersive X-ray and piezoelectric constant measurements. All the samples exhibited a tetragonal structure. The results showed that the dielectric properties increase as the Sn content increases, and Tc was lowered from 95 to 59 °C. The Tc shifted to a lower temperature due to the smaller ionic radii of Sn4+ being replaced by Zr4+ at B-sites and a decrease in the Ti–O bonds, thus weakening its interaction within the TiO6 octahedral. It was discovered that the tolerance factor becomes larger, and thus the deviation of the Sn4+ ions at B-sites are much easier, with enough space and enhanced ferroelectricity and dielectric properties. However, its piezoelectric properties were decreased since the tetragonality of the samples decreased with the addition of Sn4+ contents. The c-axis becomes shorter and reduces the dipole moment of the TiO6 octahedral. Moreover, the activation energies for Sn-doped BCZT ceramics associated with the ionization of oxygen vacancies create difficulties in electric domain rotation, thus reducing the polarizability of the samples.