Phase transitions, ferroelectric, and piezoelectric properties of lead-free piezoelectric xBaZrO.sub.3-CaTiO.sub.3-0.75BaTiO.sub.3 ceramics

Lead-free xBaZrO.sub.3-(0.25-x)CaTiO.sub.3-0.75BaTiO.sub.3; x = 0.00-0.25 ceramics were successfully prepared using the conventional solid-state reaction method. Analysis of the sintered ceramics showed that all compositions exhibited a pure phase perovskite. The effects of composition on the phase transition, ferroelectric properties, and piezoelectric properties were studied. With the increasing BaZrO.sub.3 content, the phase transition temperature (T.sub.C) decreased and the coercive field E.sub.c decreased. The phase diagram featuring a cubic-rhombohedral-tetragonal triple point (x ~ 0.125) was derived from X-ray diffraction data and dielectric data as a function of temperature. Compositions near the convergence region exhibited the maximum peak in permittivity of ~11,400 at T.sub.C. In addition, the morphotropic phase boundary compositions showed an enhancement in ferroelectric and piezoelectric properties. The composition 0.125BaZrO.sub.3-0.125CaTiO.sub.3-0.75BaTiO.sub.3 exhibited the highest strain values of 0.14 % and a d33* of 474 pm/V.