Phase boundary, poling conditions, and piezoelectric activity and their relationships in (K0.42Na0.58)(Nb0.96Sb0.04)O3–(Bi0.5K0.5)0.90Zn0.10ZrO3 lead-free ceramics

Effects of both phase boundaries and poling conditions on the piezoelectric activity of (K,Na)NbO3 (KNN)-based ceramics {e.g., (1 − x) (K0.42Na0.58) (Nb0.96Sb0.04)O3–x(Bi0.5K0.5)0.90Zn0.10ZrO3 [(1 − x)KNNS–xBKZZ]} were studied in detail, and their d33 was promoted by refining the phase compositions and choosing optimum poling conditions (i.e., poling temperature, poling electric field, and second-poling process). The rhombohedral-tetragonal phase boundary was formed in the ceramics with 0.04 < x ≤ 0.05. In addition, their piezoelectric activity was further promoted by optimizing the poling temperatures and poling electric fields as well as the second-poling methods. The ceramics with x = 0.045 have enhanced piezoelectric activity (e.g., d33 ∼ 425 pC N−1 and kp ∼ 47%), and both d33 (425 pC N−1) and TC (248 °C) of this work can match well that (d33 ∼ 416 pC N−1 and TC ∼ 253 °C) of textured (Na,K,Li)(Nb,Ta,Sb)O3 ceramics. It is worth noting that a large strain (0.297%, Smax/Emax = 582 pm V−1) was also found in the ceramics with x = 0.04, which is superior to currently reported results in KNN-based ceramics.