Improved Piezoelectricity in (K0.44Na0.52Li0.04) (Nb0.91Ta0.05Sb0.04)O3-xBi0.25Na0.25NbO3 Lead-Free Piezoelectric Ceramics

(1 - x)[(K0.44Na0.52Li0.04)(Nb0.91Ta0.05Sb0.04)O-3]-xBi(0.25)Na(0.25)NbO(3) (KNLNTS-xBNN) lead-free piezoelectric ceramics have been prepared using a conventional solid-state reaction method and the effects of BNN on their phase structure, microstructure, and electrical properties systematically studied. X-ray diffraction analysis suggested that BNN substitution into KNLNTS induced coexistence of orthorhombic-tetragonal mixed phase and thus improved the ferroelectric and piezoelectric properties. The surface morphologies indicated that different amounts of BNN had two different effects on grain growth. Good electrical properties (d(33) = 256 pC N-1, T-c = 354.27 degrees C, k(p) = 43.43%, P-r = 26.85 mu C cm(-2), E-c = 24.47 kV cm(-1)) were simultaneously obtained at x = 0.0025, suggesting that our research could benefit development of (K, Na) NbO3-based ceramics and widen their application range.