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)0.96Li0.04](Nb0.85Ta0.15)O3–xBiFeO3 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: d33 = 261 pC/N, tan δ = 0.016, Kp = 0.58, Tc = 345 °C and ɛr = 1116. Especially, the results demonstrated that the PPT of (K0.458Na0.542)0.96Li0.04](Nb0.85Ta0.15)O3 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.

Graphical abstract: The optimal piezoelectric properties, the time stability and ageing rate values of (1 − x)[(K0.458Na0.542)0.96Li0.04](Nb0.85Ta0.15)O3–xBiFeO3 lead-free piezoelectric ceramics have been obtained by using BiFeO3 as additive.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► BiFeO3-doped KNLNT ceramics were prepared by the conventional solid-state method. ► The optimal properties have been obtained for the 0.004 BiFeO3 doped ceramics. ► The ceramics hold favorable time stability and ageing rate values.