Improving non-sensitivity of sintering behavior in KNN‐based ceramics via Fe2O3 doping

The non-sensitivity of sintering behavior in piezoceramics is critical to realize the large-scale industrial productions. However, high piezoelectricity in lead-free KNN-based ceramics can usually only be achieved in very narrow sintering temperature regions. Herein, we provide a simple method to broaden the sintering temperature range with decreased sintering temperature sensitivity by adding appropriate sintering aid Fe2O3. Compared with the narrow sintering temperature range (20–30 ℃) of previous KNN-based ceramics, the prepared ceramics exhibit a much wider sintering temperature range (∼100 ℃). The optimal properties (d33 = 370 pC/N, d33* = 447 pm/V, kp = 0.47, TC = 323 ℃) are obtained in the ceramics sintered at Ts = 1040 ℃. Relevant impedance characterization demonstrates the origination (defect-dependent grain growth mechanism) of enhanced electric and sintering properties. It is believed this work can provide a feasible and effective method for widening the sintering temperature and obtaining high piezoelectricity in KNN-based material system at the same time. •A relative wide sintering temperature range (1020–1120 ℃) is obtained, which suggests the ceramics are suitable for the large-scale industrial productions.•The excellent comprehensive performance (d33 = 370 pC/N, d33*= 447 pm/V, kp = 0.47, TC = 323 ℃) are obtained in x = 0.003 ceramics sintered at Ts = 1040 ℃.•Relevant characterizations suggest that the defect-dependent grain growth mechanism play an important role in the crystal growth process, and the formation of vacancies is helpful to decrease sintering temperature in KNN-based piezoceramics.•Based on the defect-dependent grain growth mechanism, other elements with lower valence as sintering aid in KNN-based system are predicted to generate the similar result of broadening sintering temperature region.