The effect of excess lead oxide on the sintering characteristics and dielectric properties of lead magnesium niobate ceramics

The effect of lead oxide additions on sintering characteristics and dielectric properties of ferroelectric Pb3MgNb2O9 based capacitors was studied. The basic dielectric compositions were formed by solid state reaction. Densification was studied as a function of PbO content over the temperature range 900 °C to 1000 °C for sintering times one to six hours depending on the amount of additive, and the sintering temperature. Weight loss, density and shrinkage measurements of each composition were made in order to relate the effects of the excess PbO additions on the densification. The dielectric and electrical properties were then correlated to the micro structure and density. The compositions sintered at low temperatures were densified by the formation of a liquid phase during sintering. However, an increase of the amount of liquid phase does not necessarily yield optimum dielectric properties. A proper control of the sintering temperature, time and the amount of excess PbO is required for optimization of the dielectric properties --Abstract, page ii