Composition Dependent Piezoelectric Properties of Pb-free (Bi0.o5N0o 5)1-x) BaxTiO3 Ceramics

Abstract

An optimum composition for maximizing piezoelectric properties of (Bi_0.5Na_0.5)_(1-x)Ba_xTiO₃ ceramics was investigated within the range of x=0-0.1 covering rhombohedral to tetragonal phase regions of the system. A perovskite structure with two different crystal symmetries depending on the Ba content was formed with no impurity phases. A range of morphotropic phase boundary dividing rhombohedral and tetragonal phase regions was found to exist at x=0.05~0.08. As for piezoelectric properties the piezoelectric constant (d₃₃) and the electromechanical coupling factor (K_p) showed a peak value at x=0.065 within the range tested, which was 192 pC/N and 34%, respectively, implying x=0.065 as an optimum composition for piezoelectric (Bi_0.5Na_0.5)_(1-x)Ba_xTiO₃ ceramics.