Abstract: Piezoelectric ceramics with high mechanical quality factor Q_m and large piezoelectric coefficient d₃₃ are urgently required for advanced piezoelectric applications. However, obtaining both of these properties simultaneously remains a difficult challenge due to their mutually restrictive relationship. Here 0.5Pb(Ni_1/3Nb_2/3)O₃-0.5Pb(Zr_0.3Ti_0.7)O₃ piezoceramic with tetragonal (T)-rich MPB is designed as a matrix to construct the defect engineering by doping low-valent Mn ions. The strong coupling of defect dipole and T-rich phase can effectively hinder the rotation of P_s, restrict domain wall motion and improve Q_m. At the same time, the substituted Mn ions will introduce local random field, destroying the long-range ordering of ferroelectric domain and reducing domain size. The miniaturized domain structure can increase poling efficiency and inhibit the reduction of d₃₃. Guided by this strategy, Q_m has increased by more than 10 times and d₃₃ has only decreased by about 25%. The optimized electromechanical performance with Q_m = 822, d₃₃ = 502 pC/N, k_p = 0.55 and tanδ = 0.0069 can be obtained in the present study.

Key words: PNN-PZT ceramics, Defect engineering, Domain miniaturization, High mechanical quality factor Q_m, Large piezoelectric coefficient d₃₃