Piezoelectric and Dielectric Properties of (Bi0.5K0.5+x Li y )TiO3 Ceramics

Dielectric and piezoelectric properties of (Bi0.5K0.5+xLiy)TiO3 ceramics were studied in the range of x = −8–1 and y = 0–5 mol% of the stoichiometric K0.5. Secondary phases were not observed within −1 ≤ x ≤ 1 but started emerging at x ≤ −2 mol%. A tetragonal perovskite structure was maintained at all compositions despite the formation of secondary phases with K deficiency. Piezoelectric coefficient (d33) was improved due to K-vacancies facilitating domain walls movement and was further enhanced due to the microstructure improved with the tetragonality optimized by Li addition. Depolarization temperature (Td), on the other hand, depressed with K deficiency and Li addition.