Study on the Pressureless Sintering and Properties of (K<sub>0.5</sub>Na<sub>0.5</sub>)<sub>1-x</sub>Li<sub>x</sub>Nb<sub>1-y</sub>Ta<sub>y</sub>O<sub>3</sub> Lead-Free Piezoelectric Ceramics

Abstract

Potassium sodium niobate ((K0.5Na0.5)1-xLixNb1-yTayO3) powers were prepared by solid phase synthesis and (K0.5Na0.5)1-xNb1-yTayO3 lead-free piezoelectric ceramics were fabricated by the pressuerless sintering. The relationship among the powder phase composition and electric properties was studied. The results show that when x=0.5, the sintering temperature is 1050°C,and the polarization voltage is 3 kV/mm, the (K0.5Na0.5)1-xLixNb1-yTayO3 piezoelectric ceramics with the better piezoelectric properties are prepared. (The relative density is 94%, the piezoelectric constant d33=105pC/N, the planar electro-mechanical coupling coefficient kp=0.39, the medium loss tanδ=0.29, the mechanical quality factor Qm=45, and the dielectric constant εr=720). As the increase of the polarization votage, the ceramic piezoelectric properties are increased. When the polarization voltage E=3kV/mm, the polarization tends to be saturation on the whole.