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(O-i-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 degrees C to 200 degrees C. 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.

Keywords: piezoelectric; Pb-free; powder; BNT; hydrothermal