Novel 1–3 (K,Na)NbO3-based ceramic/epoxy composites with large thickness-mode electromechanical coupling coefficient and good temperature stability

Abstract The 1–3 piezoelectric composites are an important type of artificial functional materials for ultrasonic transducers. Currently, there are increasingly strong demands to replace the lead-containing materials. Excellent 1–3 0.96(K0.48Na0.52) (Nb0.96Sb0.04)O3−0.03BaZrO3−0.01(Bi0.50Na0.50)ZrO3 ceramic/epoxy (abbreviated hereafter as KNNS-0.03BZ-0.01BNZ/epoxy) piezoelectric composites were prepared by a modified dice-and-fill technique. Compared to the monolithic KNNS-0.03BZ-0.01BNZ ceramic, the developed composites possess much larger electromechanical coupling coefficient kt of 0.54–0.67 and piezoelectric voltage coefficient g33 of 64–91 × 10−3 Vm/N. In addition, these composites also possess other favorable properties such as low values of acoustic impedance Z of 6.9–13.4 Mrayl, dielectric coefficient e33 of 130–400 and mechanical quality factor Qm of 1.3–4. More importantly, kt is weakly temperature-dependence in the common usage temperature range between −30 °C and 100 °C. The result indicates that the 1–3 KNNS-0.03BZ-0.01BNZ/epoxy piezoelectric composites have a great potential for high-frequency ultrasonic transducers.