(Bi sub(1/2)Na sub(1/2))TiO sub(3)-PbTiO sub(3)- BaTiO sub(3) solid solution for piezoelectric ceramics

Piezoelectric and ferroelectric properties of a bismuth sodium titanate, (Bi sub(1/2)Na sub(1/2))TiO sub(3) (BNT)-based solid solution, (Bi sub(1/2)Na sub(1/2)) sub(1-x)) (Pb sub(a)Ba sub(b)) sub(x) TiO sub(3) (a + b = 1) (BNTX), were studied from the viewpoint of a new group of lead-free or low-lead-content piezoelectric ceramics with a rhombohedral (F sub( alpha ))-tetragonal (F sub( beta )) morphotropic phase boundary. A rhombohedral (F sub( alpha ))-tetragonal (F sub( beta )) morphotropic phase boundary was shown to exist at x greater than or less than 0.135 in the case of b = 0. BNTX ceramics are superior for piezoceramics applications in high-frequency ultrasonic uses, with a lower free permittivity, epsilon sub(33) super(T)/ epsilon sub(0), and a high electromechanical coupling factor k sub(t) or k sub(33), along with a high mechanical strength.