Piezoelectric ceramic powder synthesis of bismuth-sodium titanate by a hydrothermal process

Abstract

Hydrothermal synthesis of bismuth-sodium titanate ceramic as a lead-free piezoelectric ceramic was studied, because the hydrothermal method (HTM) has been utilized for commercial production of powders. To synthesize bismuth-sodium titanate ceramic powder by a hydrothermal process using a mixed aqueous solution of metal-salts, Bi(NO3)3, Ti-isopropoxide (Ti(Oi- C3H7)4), titanium tetra-n-butoxide (Ti(O-n-C4H9)4) and Na2CO3 were used as starting materials. Two kinds of mineralizers, NaOH and KOH, were used. The hydrothermal reaction temperature was in the range from 160 oC to 200 oC. We investigated the effects of the hydrothermal temperature, time, amount of mineralizers, pH, solubility in solutions on phase formation and the properties of the powders. Synthesized bismuth-sodium titanate ceramic was analyzed with an X-ray diffractometer (XRD), a scanning electron microscope (SEM) and a field emission scanning electron microscope (FESEM). The alkaline concentration had a great effect on the phase formation and morphology of the powders. (Bi1/2Na1/2)TiO3-based nanocrystalline particles with a perovskite structure were successfully synthesized.