The effects of Ca, Zr and Sn substitutions into a ternary system of BaTiO3–BaSnO3–BaZrO3 towards its dielectric and piezoelectric properties: a review

The discovery of the dopant effects on BaTiO3 has attracted great interest after a compound of 50(BaTi0.8Zr0.2O3)–50(Ba0.7Ca0.3TiO3) system exhibited extraordinarily high piezoelectric properties (d33 > 600 pC/N). Recently, modifications made on the BaTiO3-based piezoelectric materials, particularly at the A-site, have gained the most attention due to the existence of the morphotropic phase boundary (MPB) region. In this paper, we reviewed several dopants that have been extensively used to enhance the piezoelectric and dielectric properties of a BaTiO3 such as Sn and Zr. A ternary triangle of BaTiO3–BaSnO3–BaZrO3 is used to evaluate the correlations between the changes in the Sn- and/or Zr-doped BaTiO3 piezoelectric ceramic properties. The structural changes that have been affected by the dopant contents were also comprehensively reviewed. There is clear evidence that the dopants significantly affect the intrinsic properties of the BaTiO3-based ceramic materials. The dielectric constant εr value increases from 1900 to ~ 6000 at room temperature, while the piezoelectric constant d33 value is also increased from 191 pC/N to ~ 600 pC/N. All the compositions described in this review were prepared by using a conventional solid-state route.