Preparation and characterization of lead iron tantalate thick films

Thick film compositions based on solid solutions of relaxor ferroelectric Pb(Fe1/2Ta1/2)O-3 and normal ferroelectric PbTiO3 were prepared and applied for class 11 capacitors. The dielectric layers were fired at 870 degrees C. In order to shift the temperature of ferroetectric-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 degrees C and in the frequency range 10 Hz-1 MHz. Resistivities of the thick films were measured in the temperature range 20-500 degrees 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 10(12) Omega cm), low temperature coefficient of capacitance and low electrical field dependence of capacitance. (c) 2005 Elsevier Ltd. All rights reserved.