High temperature piezoelectricity of sodium substituted lithium niobate ceramics

Ceramics of Sodium substituted Lithium Niobate (Li/sub 1-x/Na/sub x/NbO/sub 3/) were prepared by mixed oxides and sol-gel methods. The phase diagram of the system was studied by HT XRD, calorimetry and dielectric measurements. An automatic iterative procedure was used for the determination of the piezoelectric, elastic and dielectric coefficients from impedance measurements as a function of the temperature. Piezoelectric activity was found up temperatures above 600/spl deg/C. The effect of Na content on the thermal stability of the piezoelectric properties is discussed.