Development of new chemical processes to lead-free piezoelectric and ferroelectric materials

In our efforts to develop new lead-free piezoelectric materials, K0.5Na0.5NbO3 (KNN)-based ceramics were prepared by a new solid-state synthetic method using potassium fluoride (KF) as a sintering agent. The addition of KF resulted in ceramics with enhanced density and quality. Piezoelectric properties were improved over those of conventionally sintered KNN ceramics. Chemical analyses were performed by means of Energy Dispersive Spectroscopy (EDS) and X-ray Photoelectron Spectroscopy (XPS) to deduce the sintering mechanism. The ferroelectric solid-solution of (1-x)(K0.5Na0.5)NbO3-xBiAlO3 was synthesized by solid state reaction. A partial temperature-composition phase diagram was established, which includes a morphotropic phase boundary in the composition range 0.002 (K0.5Na0.5)+ + Nb5+, the temperature dependences of dielectric constant exhibit increasingly broadened peaks and significant frequency dispersion as the BA concentration increases.