LOW-FIRING SOL–GEL DERIVED Mn-DOPED 0.92(K0.5Na0.5)NbO3–0.08LiNbO3 LEAD-FREE CERAMICS WITH ENHANCED PIEZOELECTRIC PROPERTIES

Abstract

Mn -doped 0.92( K 0.5 Na 0.5) NbO 3–0.08 LiNbO 3 (0.92KNN–0.08LN) lead-free piezoelectric ceramics have been prepared by a developed sol–gel routes using Nb2O5 as Nb source. Due to the high quality of gel precursor, Mn -doped 0.92KNN–0.08LN nanopowders with the mean particle size about 20 nm were obtained at 500°C. The addition of Mn can promote the densification of nanopowders effectively at 950°C, and also influences in a pronounced way both the crystal structure and microstructure of the materials. With the increase of the amount of Mn addition, 0.92KNN–0.08LN ceramics are transformed from dominant orthorhombic to coexistence of the orthorhombic and tetragonal phases, and the grain sizes are enhanced simultaneously. Optimized parameters, such as d33 = 212 pC/N and k p = 0.46, were achieved in 0.2 Mn -doped 0.92KNN–0.08LN systems, which are good candidate material for lead-free piezoelectric devices.