Principal Investigator Yet-Ming Chiang
Alkaline bismuth titanates (prototype: Na1/2Bi1/2Ti3) are attractive as potential lead-free, polycrystalline substitutes for widely-used lead perovskite piezoelectric and electrostrictive compounds such as PZT and PMN. However, they are considered to be difficult to pole, and have not to date exhibited sufficiently high piezoelectric response and electromechanical coupling to be useful substitutes. Research on single crystal doped NBTs has revealed that the introduction of A-site cation vacancies dramatically improves poling (an extrinisic response) as well as d33 (intrinsic response). In this project, the influence of deliberately introduced A-site cation deficiency in NBT, accomplished by doping and cation nonstoichiometry variations, on dielectric and electromechanical properties of polycrystalline NBT is being studied. Solid-state reaction, sol-gel synthesis, and melt-quenching are being explored as methods for obtaining single-phase cation nonstoichiometric powders, for subsequent preparation as polycrystalline specimens.