Hydrothermal synthesis of (Bi1/2Na1/2)TiO3 piezoelectric ceramics

Hydrothermal synthesis of (Bi1/2Na1/2)TiO3-based ceramics for lead-free piezoelectric ceramics was studied, because the hydrothermal method (HTM) had been utilized for commercial production of powders. To synthesize (Bi1/2Na1/2)TiO3-based ceramics powder by hydrothermal process using 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. Hydrothermal reaction temperature was in the range from 160 °C to 200 °C. We investigated the effects of hydrothermal temperature, time, amount of mineralizers, pH, and solubility in solutions on phase formation and the properties of powders. Synthesized (Bi1/2Na1/2)TiO3-based were analyzed with an X-ray diffractometer (XRD), a scanning electron microscope (SEM) and a field emission scanning electron microscope (FESEM). Alkaline concentration had a great effect on the phase formation and morphology of the powders. (Bi1/2Na1/2)TiO3-based nanocrystalline particles with perovskite structure were successfully synthesized.