Laser sintering of (K_0.5Na_0.5NbO₃)-LiTaO₃ lead-free ceramics with novel piezoelectric properties Available to Purchase

In this paper, by CO₂ laser sintering technique, grain-oriented K_0.5Na_0.5NbO₃-LiTaO₃ ceramics with high dense of 92% theoretical density were prepared. The dielectric, piezoelectric and electromechanical properties were found to be ε ∼ 510, d₃₃ ∼ 120 pC/N, and k_p ∼ 36%, while with high Curie temperature of about 420 °C and low dielectric loss of about 0.03 ∼ 0.04. The high dense (92% theoretical density) structure with the texture character of grain-orientation is the factors to obtain good piezoelectric properties of the ceramics. The preparation of high dense ceramic is due to the suppression of O₂ discharged by the coaxial gas injection systems on the volatilization of the K⁺, Na⁺ and Li⁺ during laser heating. An interesting change of grain shape from isometric to anisometric (needle-like) relating to the grain-orientation was observed obviously in the laser-sintered KNN-based. It was concluded that the enhanced Curie temperature associated with the high temperature phase transition was induced by the instant adjustment of laser power density from 0.07 kW/cm² to 0.28 kW/cm² just during 2 ∼ 5 s.