Enhanced piezoelectricity around the tetragonal/orthorhombic morphotropic phase boundary in (Na,K)NbO3-ATiO(3) solid solutions

The high density perovskite titanates-modified potassium-sodium niobate solid solutions (1-x)(Na0.5K0.5) NbO3-xBaTio(3) and (1-x)(Na0.5K0.5)NbO3-xSrTiO(3) have been prepared by the solid state reaction method. The phase diagram summarized from the dielectric property measurement reveals that there exists a tetragonal/orthorhombic morphotropic phase boundary for both the solid solutions. The piezoelectric properties show enhanced behavior at around the tetragonal/orthorhombic morphotropic phase boundary. It is believed that the origin for the high piezoelectric performance (Na;K)NbO3-based lead-free piezoelectric ceramics is the same as that for the lead zinc niobate-lead titanate solid solution.