Sintering and electrical properties of La-modified (Na0.52K0.45Li0.03)1−3xLax(Nb0.88Sb0.09Ta0.03)O3 lead-free ceramics

(Na0.52K0.45Li0.03)1−3xLax(Nb0.88Sb0.09Ta0.03)O3 (NKLLxNST) lead-free ceramics were prepared by normal sintering and their dielectric and piezoelectric properties were investigated. The X-ray methods indicate that the NKLLxNST ceramics with x≤0.003 present a pure perovskite phase at room temperature. The bulk density of NKLLxNST ceramics increases with proper amount of La2O3 contents, and reaches its highest value of 4.544 g/cm3 with the addition of 0.3 mol% La2O3. At x=0.003, remnant polarization Pr, piezoelectric constant d33 and planar mode electromechanical coupling factor kp of NKLLxNST ceramics reach the highest values of 37.80 μC/cm2, 346 pC/N and 40%, respectively, exhibiting excellent “soft” piezoelectric characteristics, demonstrating a tremendous potential of the compositions studied for device applications.