Effects of K4CuNb8O23 on the structure and electrical properties of lead-free 0.94(Na0.5K0.5)NbO3-0.06LiNbO3 ceramics

Dense K4CuNb8O23-modified (K0.5Na0.5)(0.94)Li0.06NbO3 ceramics were prepared by normal sintering. The effects of K4CuNb8O23 on the phase structure, microstructure and electrical properties of the ceramics were studied. Results showed that K4CuNb8O23 induced a perovskite structure transition from coexistence of orthorhombic and tetragonal phases to orthorhombic symmetry. The addition of K4CuNb8O23 promoted the sintering of(K0.5Na0.5)(0.94)Li0.06NbO3 ceramics and simultaneously caused the grain growth. Moreover, K4CuNb8O23-doping changed the (K0.5Na0.5)(0.94)Li0.06NbO3 to "hard" ceramics and significantly enhanced the mechanical quality factor Q(m). It was found that the (K0.5Na0.5)(0.94)Li0.06NbO3 ceramics doped with 0.60 mol% K4CuNb8O23 exhibited a high mechanical quality factor (Q(m) similar to 983) as well as relatively large d(33) (136 pC/N) and k(p) (35.9%), suggesting that this material is a promising candidate for lead-free piezoelectric ceramics for high-frequency applications. (C) 2009 Elsevier Ltd. All rights reserved.