Preparation and characterization of lead iron tantalate thick films

Thick film compositions based on solid solutions of relaxor ferroelectric Pb(Fe1/2Ta1/2)O3 and normal ferroelectric PbTiO3 were prepared and applied for class II capacitors. The dielectric layers were fired at 870 °C. In order to shift the temperature of ferroelectric–paraelectric transition upwards the addition of 10, 15 and 20 mol% of PbTiO3 was used. Introduction of 0.1–0.5 mol% of MnO2 or Co3O4 to the pastes resulted in an increase in their resistivity. The electric permittivity and dissipation factor of the layers were determined in the temperature range from −55 to 180 °C and in the frequency range 10 Hz–1 MHz. Resistivities of the thick films were measured in the temperature range 20–500 °C. Microstructure of the layers was characterized by a scanning electron microscope. The advantageous features of the developed thick films were: lack of any nonferroelectric fluxes, dense microstructure, relatively high dielectric permittivity (300–1900), high resistivity (about 1012 Ωcm), low temperature coefficient of capacitance and low electrical field dependence of capacitance.