Tdk Electronics Company, Limited

Hitoshi Tanaka

Shinobu Fujiwara

Kiyoshi Furukawa

Nobuaki Kikuchi

Osamu Iizawa

Hisayoshi Ueoka

Hitoshi Masumura

A novel ceramic composition exhibiting a solid solution structure of Pb(Fe.sub.1/2 Nb.sub.1/2)O.sub.3 -Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 -Pb(Mg.sub.1/2 W.sub.1/2)O.sub.3, can be sintered at a low sintering temperature; have a high insulation resistance; have a relatively high dielectric constant in the high dielectric type ceramic dielectrics, and; have a low dielectric loss. A particular amount of the additives, i.e., Pb-(Mn.sub.2/3 W.sub.1/3)O.sub.3, Pb(Mb.sub.1/2 W.sub.1/2)O.sub.3 Pb(Mn.sub.1/2 Nb.sub.2/3)O.sub.3, MnO, Pb(Mn.sub.1/3 Ta.sub.2/3)O.sub.3, Li.sub.2 O, Cr.sub.2 O.sub.3 and CeO.sub.2, is added into the composition mentioned above.

High dielectric constant type ceramic composition consisting essentially

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.

High dielectric constant type ceramic composition

A novel ceramic composition exhibiting a solid solution structure of Pb(Fe.sub.2/3 W.sub.1/3)O.sub.3 --Pb(ZrO.sub.3), can be sintered at a low sintering temperature; have a high insulation resistance; have a relatively high dielectric constant in the high dielectric type ceramic dielectrics; have a low dependence of dielectric constant upon temperature, and; have a low dielectric loss. A particular amount of the additives, i.e., MnO, Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3, Pb(Mn.sub.1/2 W.sub.1/2)O.sub.3, Pb(Mn.sub.2/3 W.sub.1/3)O.sub.3, Pb(Mn.sub.1/3 Ta.sub.2/3)O.sub.3, Cr.sub.2 O.sub.3 and CeO.sub.2, is added into the composition mentioned above.

A novel ceramic composition exhibiting a solid solution structure of Pb(Fe.sub.1/2 Nb.sub.1/2)O.sub.3 --Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3, can be sintered at a low sintering temperature; have a high insulation resistance; have a relatively high dielectric constant in the high dielectric type ceramic dielectrics, and; have a low dielectric loss. A particular amount of the additives, i.e., pb(Mn.sub.1/2 W.sub.1/2)O.sub.3, Pb(Mn.sub.1/3 Nb.sub.2/3)O.sub.3, MnO, Pb(Mn.sub.1/3 Ta.sub.2/3)O.sub.3 Li.sub.2 O, Cr.sub.2 O.sub.3 and CeO.sub.2, is added into the composition mentioned above.

A novel ceramic composition exhibiting a solid solution structure of Pb(Fe.sub.1/2 Nb.sub.178 )O.sub.3 -Pb(Mg.sub.1/3 Ta.sub.2/3)O.sub.3, can be sintered at a low sintering temperature; have a high insulation resistance; have a relatively high dielectric constant in the high dielectric type ceramic dielectrics, and; have a low dielectric loss. A particular amount of the additives, i.e., Pb(Mn.sub.1/2 W.sub.1/2)O.sub.3, Pb(Mn.sub.1/3 Nb.sub.170 )O.sub.3, MnO, Pb(Mn.sub.1/3 Ta.sub.170 )O.sub.3, Li.sub.2 O, Cr.sub.2 O.sub.3 and CeO.sub.2, is added into the composition mentioned above.

An improved reduction-reoxidation type semiconducting ceramic capacitor and the method for producing the same are disclosed. The main components of the substrate of the capacitor are CaTiO.sub.3, SrTiO.sub.3 and Bi.sub.2 O.sub.3 .multidot.xTiO.sub.2. Said substrate also contains at least one member selected from the group consisting of manganese, cobalt, nickel, chromium, vanadium, niobium, tantalum, lanthanum and cerium ions in total amounts of 0.025 to 0.4% by weight. The capacitor according to the present invention excels, in the temperature independency of the capacitance and tan .delta., etc.

Reduction-reoxidation type semiconducting ceramic capacitor

A sintered ceramic dielectric body is provided which exhibits a high dielectric constant as well as a low dielectric loss and almost no variation in the dielectric constant and the dielectric loss with respect to a wide variation of an applied high AC or DC voltage, respectively. The ceramic dielectric composition consists essentially, by weight, of approximately 18 to 70% of strontium titanate (SrTiO.sub.3), approximately 4 to 75% of barium titanate (BaTiO.sub.3), 2.5 to 17.4% of bismuth oxide (Bi.sub.2 O.sub.3) and 1.7 to approximately 20% of titanium oxide (TiO.sub.2); the ratio by mole of the titanium oxide (TiO.sub.2) to the bismuth oxide (Bi.sub.2 O.sub.3) being within the range from approximately 1 to 18.

Sintered ceramic dielectric body

A ceramic dielectric composition is provided including 30 to 94% by mol of SrTiO.sub.3, 1 to 22% by mol of Bi.sub.2 O.sub.3 and 5 to 69% by mol of TiO.sub.2, and further including 0.1 to 20% by weight of MgO with respect to the total weight of the above-mentioned three compounds SrTiO.sub.3, Bi.sub.2 O.sub.3 and TiO.sub.2, whereby the ceramic dielectric composition has a high dielectric constant and a low dielectric loss and further the variations of the dielectric constant and the dielectric loss with respect to the variation of an applied voltage, are respectively, very small.

Ceramic dielectric composition

A dielectric ceramic composition comprises as principle constituents, 86 - 99.6 mole % of barium titanate, 0.2 - 10 mole % of niobium pentaoxide and 0.2 - 4 mole % of cerium oxide.

An improved reduction-reoxidation type semiconducting ceramic capacitor and the method for producing the same are disclosed. The main components of the substrate of the capacitor are CaTiO.sub.3, SrTiO.sub.3 and Bi.sub.2 O.sub.3.xTiO.sub.2. Said substrate also contains at least one member selected from the group consisting of manganese, cobalt, nickel, chromium, vanadium, niobium, tantalum, lanthanum and cerium ions in total amounts of 0.025 to 0.4% by weight. The capacitor according to the present invention excels, in the temperature independency of the capacitance and tan .delta., etc.

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Tokyo, Japan

Hitoshi Tanaka