US 4,309,295 A · Grain boundary barrier layer ceramic dielectrics and the method of manufacturing capacitors therefrom

Abstract

A major amount of strontium titanate is modified with additions of lanthanide series rare earth aluminates, titanates and transition metal oxides to provide sintered semiconductive ceramics with enhanced temperature and voltage stability. The modified strontium titanate ceramic, having the general formula: (1-x)SrTiO.sub.3 +x(1-y)[(1-z)LnAlO.sub.3 +zLn.sub..66 TiO.sub.3]+xyLnMO.sub.3, is coated with a fritted electrode material and fired at a temperature below the melting point of the electrode material to cause the frit to diffuse into the ceramic and form insulating boundaries around the ceramic grains. Ceramic capacitors so formed are characterized by their excellent electrical properties, particularly their improved temperature stability as evidenced by extremely low changes in capacitance with temperature.

Claims13

Dependent claims

A grain boundary barrier layer ceramic composition consisting essentially of a major amount of sintered strontium titanate and having the formula:

(1-x)SrTiO.sub.3 +x(1-y)((1-z)LnAlO.sub.3 +zLn.sub.0.66 TiO.sub.3)+xyLnMO.sub.3 ;
where Ln is selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu;
where M is selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, Ta and W;
and, where x=0.02 to 0.06, y=0 to 0.50 and z=0 to 1.00;
and,
having diffused therein a barrier layer material consisting essentially of Bi.sub.2 O.sub.3 or a mixture of a major amount of Bi.sub.2 O.sub.3 with the balance comprising CdO or PbO.

3 more elements

Dependencies are inferred from the claim text.

Grain boundary barrier layer ceramic dielectrics and the method of manufacturing capacitors therefrom

Life of this patent

Grain boundary barrier layer ceramic dielectrics and the method of manufacturing capacitors therefrom

Life of this patent

Abstract

Claims13