Preparation And Electric Properties Of Lead-free Na_0.5K_0.5NbO₃-LiTaO₃ Piezoelectric Ceramics

Piezoelectric materials based on Pb(Zr,Ti)O₃ solid solution (PZT) have been widely used , but one of the major drawbacks of PZT materials is the lead content. Accordingly, these materials may be restricted in near future because of environmental issues. In the field of lead-free piezoelectric ceramics, many researches focus on the alkali metal niobate-based materials. In this paper, sodium potassium niobate-based ceramics were selected as the experimental system. (1—x) Na_0.5K_0.5NbO₃-xLiTaO₃ ceramics was prepared by traditional method, and the morphotropic phase boundary(MPB) was confirmed. Plated-like powder NaNbO₃ were synthesized by molten salt process;textured NKN-LT ceramics were fabricated by TGG and RTGG technique.The results shows that the ceramic with the composition of 0.94NKN-0.06LT is closed to MPB and has better piezoelectric properties, the composition of NKN-LT ceramic were optimized for fabrication texture NKN-LT ceramics.From analyzing the processing parameters and rules of selecting template particles of TGG and RTGG technique, plated-like powder BIT and NN, KN were selected. Plated-like powder NN templates were synthesized by two-step molten salt process. The reaction were explained and then made out the processing parameters of NN templates. The effects of excessive Na₂CO₃ content on replacement reaction were investigated systematically. The plated-like powder NN was synthesized by two-step molten salt process. The average size of plated-like powder NN is 10²0μm in diameter and 1³Î¼m in thickness. Plated-like powder NN is suitable for tape casting.The NKN-LT ceramics were fabricated by TGG an RTGG method and tape casting process. Plated-like powder BIT and NN were selected as the template for texture ceramics. The ceramic process parameter, texture fraction, microstructure and piezoelectric properties were discussed.