Method of making a multilayer piezoelectric composite

A process of producing a multilayer piezoelectric composite comprising the steps of:

• (a) preparing green sheets of a lead zirconate titanate piezoelectric ceramic by molding lead zirconate titanate having a particle diameter of not more than 0.5 .mu.m which is obtained by heat treating equimolar quantities of crystalline zirconium titanate represented by the general formula Zr.sub.x Ti.sub.1-x O.sub.z and having a particle diameter of not more than 0.3 .mu.m and lead oxide at a temperature of not more than 800.degree. C. and pulverizing the resultant product;
• (b) preparing a bonded laminate by laminating and bonding together under pressure green sheets of plural kinds of lead zirconate titanate piezoelectric ceramics, at least one layer of which has a temperature coefficient of frequency constant whose polarity is opposite to that of the other layers;
• and
• (c) sintering the bonded laminate at a temperature of not higher than 1100.degree. C. so that substantially no interdiffusion takes place between the layers;
• thereby providing a multilayer piezoelectric composite having an absolute value for the temperature coefficient of frequency constant which is smaller than the absolute value of the temperature coefficient of frequency constant of any one of the layers.