SmAlO3-modified (K0.5Na0.5)0.95Li0.05Sb0.05Nb0.95O3 lead-free ceramics with a wide sintering temperature range

•Proper addition of SA enhances mechanical quality factor of the KNLNS ceramics.•The doping of SA broadens the sintering temperature range of the ceramics.•The high d33 and Qm mean that the x = 0.005 sample is suitable for high frequency applications.

Lead-free ceramics (1 − x)(K0.5Na0.5)0.95Li0.05Sb0.05Nb0.95O3-xSmAlO3 (KNLNS-xSA) were prepared by conventional sintering technique. The phase structure, dielectric and piezoelectric properties of the ceramics were investigated. All compositions show a main perovskite structure, exhibiting room-temperature symmetries of tetragonal at x ≤ 0.0075, of pseudo-cubic at x = 0.0100. The Curie temperature of KNLNS-xSA ceramics decreases with increasing SmAlO3 content. Moreover, the addition of SmAlO3 can effectively broaden the sintering temperature range of the ceramics. The KNLNS-xSA ceramic with x = 0.0050 has an excellent electrical behavior of piezoelectric coefficient d33 = 226 pC/N, planar mode electromechanical coupling coefficient kp = 38%, dielectric loss tan δ = 3.0%, mechanical quality factor Qm = 60, and Curie temperature TC = 327 °C, suggesting that this material could be a promising lead-free piezoelectric candidate for piezoelectric applications.