Effects of BiAlO3 on structure and electrical properties of K0.5Na0.5NbO3–LiSbO3 lead-free piezoceramics

(1−x)(0.948 K0.5Na0.5NbO3–0.052LiSbO3)–xBiAlO3 (KNNLS–xBA) lead-free piezoceramics were synthesized by conventional solid state reaction method. The compositional dependence of phase structure and electrical properties of the ceramics was systemically studied. XRD patterns revealed that all the ceramic samples possessed pure perovskite structure. In addition, polymorphic phase transition (PPT) for the ceramics with BA doping could not be observed in the measuring range from room temperature to 500 °C. Within the studied range of BA addition, the ceramics with x = 0.002 represented a relatively desirable balance between the degradation of the piezoelectric properties, improvement in temperature stability and mechanical quality factor. It was found that the KNNLS–0.002BA ceramics exhibited optimum overall properties (d33 = 233 pC/N, kp = 35%, tanδ = 0.047, Pr = 27.3 μC/cm2, Qm = 56 and Tc = 349 °C), suggesting that this material should be a promising lead-free piezoelectric candidate for piezoelectric applications.

► In this study, the temperature of the polymorphic phase transition (PPT) was shifted below room temperature with the increasing of BiAlO3 content.
► The mechanical quality factor Qm was improved (Qm = 56), which was about 1.6 times as large as the pure KNNLS ceramics (Qm = 35).
► The dielectric loss tanδ was decreased due to the “hardening” effect of BiAlO3 doping.
► The other electrical properties still maintained relatively high levels: d33 = 233 pC/N, kp = 35%, Pr = 27.3 μC/cm2 and Tc = 349 °C, when x = 0.002.