Microstructure and electrical properties of Ti-modified (Na0.5K0.5)(Ti x Nb1-x )O3 lead-free piezoelectric ceramics

Ti-Modified (Na0.5K0.5)(Ti (x) Nb1-x )O-3 (NKNT) piezoelectric ceramics were fabricated by double-layer buried powder process at 1020A degrees C for 2 h. The microstructures, and piezoelectric and dielectric properties of the lead-free NKNT ceramics were investigated. X-ray diffraction results indicated that Ti4+ had diffused into the (Na0.5K0.5)NbO3 lattices to form a solid solution with a perovskite structure. The introducing of Ti into the (Na0.5K0.5)NbO3 solid solution effectively reduced the sintering temperature and densified the microstructure with a decreased grain size. The highest relative density reached more than 90%. The highest piezoelectric dielectric coefficient d (33) and planar mode electromechanical coupling coefficient k (p) were 110 pC/N and 19.5%, which were obtained in the NKNT ceramic with 1 mol% Ti. The piezoelectric properties of the NKNT ceramics were enhanced by aging in air for a period of time owing to the compensation of oxygen vacancies.