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.