Phase structures, electrical properties and temperature stability of (1-x)[(K0.458Na0.542)0.96Li0.04](Nb0.85Ta0.15)O3-xBiFeO3 ceramics

The addition of BiFeO3 in the ceramics shifts the PPT below room temperature to improve the temperature stability of KNN-based ceramics. The phase structure, microstructure, dielectric, piezoelectric properties and temperature stability of (1 - x)[(K0.458Na0.542)(0.96)Li-0.04](Nb0.85Ta0.15)O-3-xBiFeO(3) piezoelectric ceramics were investigated. The phase structure of these ceramics changed from tetragonal phase to pseudo cubic phase with BiFeO3 additives. The optimal piezoelectric properties were obtained at x = 0.004, which were listed as follows: d(33) = 261 pC/N, tan delta = 0.016, K-p = 0.58, T-c = 345 degrees C and epsilon(r) = 1116. Especially, the results demonstrated that the PPT of (K0.458Na0.542)(0.96)Li-0.04](Nb0.85Ta0.15)O-3 ceramics has been shifted below room temperature successfully by the addition of BiFeO3. The time stability and ageing rate values of the ceramics with x = 0.000 were 15% and 7.8%. These values decrease to 4.97% and 6.09% at x = 0.004, respectively, showing that the ceramics have better temperature and time stability for the polymorphic phase transition below room temperature. (C) 2011 Elsevier B. V. All rights reserved.