Grain boundary layer dielectric ceramic compositions.

摘要

Grain boundary layer dielectric ceramic compositions comprising semiconductive ceramic grains having a composition of 50.23 to 49.47 mol% of SrO and CaO, 49.72 to 50.23 mol% TiO2, 0.05 to 0.3 mol% of Nb2O5, substantially each of said grains being surrounded by grain boundary layer dielectric materials which is formed by grain boundary diffusion of a mixture having a composition of 90 to 14.3 mol% of Bi2O3 and 10 to 85.7 mol% of Cu2O, or a composition in which said mixture of Bi2O3 and Cu2O are substituted by less than 4 mol% of MnO2 and/or less than 6 mol% of B2O3 and or less than 20 mol% of Li2O. With these ceramic compositions there may be provided (a) ceramic capacitors with the temperature coefficient of capacitance of less than +/-20%, the apparent permeability of higher than 35,000, the dissipation factor (tan delta ) of less than 0.01 and the breakdown voltage of higher than 500 V/mm; (b) ceramic capacitors with the temperature coefficient of capacitance of less than +/-10%, the apparent permeability of higher than 20,000, the dissipation factor or less than 0.01 and the breakdown voltage of higher than 700 V/mm; or (c) ceramic capacitors with the temperature coefficient of less than +/-5%, the apparent permeability (or apparent dielectric constant of higher than 5,000, the dissipation factor (or dielectric loss) of less than 0.01% and the breakdown voltage of higher than 700 V/mm.