Electromechanical properties and high power characteristics of Pb-free hard piezoelectric ceramics in the (BiNa 0.88 K 0.08 Li 0.04 ) 0.5 (Ti 1 -x Mn x )O 3 (x = 0, 0.014, 0.015, and 0.016) system were studied. Mn doping resulted in a considerable enhancement of mechanical quality factor Q m and vibration velocity. The lowest mechanical and dielectric losses were achieved in 1.5 mol% Mn-doped ceramics with a planar Q m of about 970 and tand of 0.89%. The heat dissipation and resonance frequency shift under high drive condition were remarkably suppressed upon Mn doping. The maximum vibration velocity was increased from 0.28 m/s in undoped ceramic to 0.6 m/s in 1.5 mol% Mn-doped composition. The results of this study revealed that Mn-doped BNT-based piezoelectrics exhibited a superior high power performance compared to their lead-based counterparts such as PZT4 and PZT8 ceramics.

We report that an obvious difference in the “domain stabilization” effect between 1.0 mol. % Mn doped (Ba1−xSrx)TiO3 and (Pb1−xSrx)TiO3 piezoelectrics with a similar c/a ratio and aging treatment, though typically “increased” stabilization effect occurs with the increase of c/a in each system. The three-time larger microscopic defect dipole field Ei in lead-system from P-E measurements suggests the more aligned defect dipoles through kinetically easier hopping of oxygen vacancy originated from local structure rather than the average structure like c/a may be a primary cause of the strong domain stabilization effect. This may help on the hardening functionality improvement of lead-free systems.

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