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AssigneeTDK Electronics Co., Ltd.
InventorsShinobu Fujiwara, Kiyoshi Furukawa, Nobuaki Kikuchi, Osamu Iizawa, Hitoshi Tanaka
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A basic ceramic composition of high dielectric constant type ceramic composition comprises from 68.67 to 69.19% of PbO, from 3.67 to 4.09% of MgO, from 24.17 to 26.99% of Nb.sub.2 O.sub.5 and from 0.25 to 2.97% of TiO.sub.2, all percentages being by weight. Modified composition may comprise additive of Pb(Mn.sub.2/3 W.sub.1/3)O.sub.3, Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3, Pb(Mn.sub.1/3 Ta.sub.2/3)O.sub.3, Pb(Mn.sub.1/2 W.sub.1/2)O.sub.3, MnO, and MgO. Modified composition may comprise Ba, Sr and Ca, which replace Pb of the basic ceramic composition. In a modified composition, the content of B site elements may be larger than that of A site element of an ABO.sub.3 crystal of the high dielectric constant type ceramic composition. A high dielectric constant, low dielectric loss, low temperature dependence of capacitance, high insulation resistance and a low sintering temperature are provided by the ceramic compositions of the present invention.
A high dielectric constant type ceramic composition, characterized in that said composition consists essentially of a basic ceramic composition of from 68.67 to 69.19% of PbO, from 3.67 to 4.09% of MgO, 24.17 to 26.99% of Nb.sub.2 O.sub.5 and from 0.25 to 2.97% of TiO.sub.2, all percentages being by weight.
A high dielectric constant type ceramic composition, characterized in that said composition consists essentially of from 60 to 98 molar% of Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 and from 2 to 40 molar% of PbTiO.sub.3, and further, from 0.2 to 8.0 parts by weight of at least one additive oxide selected from the group consisting of Bi.sub.2 O.sub.3 and WO.sub.3, based on 100 parts by weight of total weight of Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 and PbTiO.sub.3.
Dependencies are inferred from the claim text.