Lanthanum and gallium co-modified BiFeO/sub 3/-PbTiO/sub 3/ crystalline solutions: lead reduced morphotropic phase boundary (MPB) piezoelectric ceramics

Crystalline solutions of (1-x)(Bi,La) (Ga,Fe)O/sub 3/-xPbTiO/sub 3/ (BLGF-PT) have been developed using conventional mixed oxide ceramic processing. An attractive feature is that BLGF-PT has electrical resistivity up to 10/sup 13/ /spl Omega//spl middot/cm at room temperatures. The MPB of (1-x)BLGF-xPT was shifted to higher x content with increasing La concentration. The La substituent was also found to decrease the ferroelectric coercive field, resulting in significantly dielectric and piezoelectric properties. The dielectric constant K and piezoelectric d/sub 33/ constant of 1760 and 295 pC/N have been achieved for BLGF-PT with La-20 at% and x=0.43, a composition in the vicinity of MPB. BGF-0.3PT (La-0, x=0.3) exhibited great remnant polarization Pr and strain of 67 /spl mu/C/cm/sup 2/ and 0.4% respectively, under an electric field of 150 kV/cm. Our results clearly demonstrate that BLGF-PT is competitive and alternative piezoelectric materials to conventional Pb(Zr,Ti)O/sub 3/ (PZT) ceramics, served as piezoelectric and high power components, but in significantly lead reduced forms.