Tdk Electronics Company, Limited

Tdk Corporation

Tdk Kabushiki Kaisha

Shinobu Fujiwara

Hitoshi Tanaka

Kiyoshi Furukawa

Nobuaki Kikuchi

Osamu Iizawa

Hisayoshi Ueoka

Yasunobu Oikawa

Hitoshi Masumura

Masahiro Yahagi

Shuichi Itagaki

Shuichi Ono

Hirotaka Yamamoto

Sho Masujima

Junichi Sutoh

Hisao Abe

Tsunehiko Yoshioka

Atsushi Satoh

Yoshifumi Midori

Kenichi Umeda

Iwaya Shoichi

Masahide Shibuya

Tetsuya Hattori

Minoru Obara

A semiconductive ceramic composition capable of exhibiting excellent electrical and physical characteristics sufficient to be used for a boundary-layer type semiconductive ceramic capacitor and such a capacitor capable of being increased in dielectric constant and insulation resistance and exhibiting excellent solderability and tensile strength of electrodes. The composition includes a SrTiO.sub.3 base material and an additive for semiconductivity consisting of Y.sub.2 O.sub.3 and Nb.sub.2 O.sub.5. The Y.sub.2 O.sub.3 and Nb.sub.2 O.sub.5 each are present in an amount of 0.1 to 0.4 mol % based on the composition. The capacitor includes a semiconductive ceramic body formed of the composition, a first conductive layer formed on each of both surfaces of the body and a second conductive layer formed on the first conductive layer. A process for manufacturing the capacitor is also provided.

Semiconductive ceramic composition and semiconductive ceramic capacitor

Semiconductive ceramic composition and semiconductor ceramic capacitor

A high dielectric porcelain composition having, as a main component, a Pb(Mg 1/3, Nb 2/3)O.sub.3 -PbTiO.sub.3 -Pb(Mn 1/3, Nb 2/3)O.sub.3 system including 95 mol. % of Pb(Mg 1/3, Nb 2/3)O.sub.3, 5 mol. % of PbTiO.sub.3 and 0.5 weight % of Pb(Mn 1/3, Nb 2/3)O.sub.3, and, in addition, a sub-component including PbO and ZnO. Such a dielectric porcelain is capable of being sintered at a temperature lower than 1000.degree. C. A method of reducing the sintering temperature of such a high dielectric porcelain composition, is also provided.

High dielectric porcelain composition and method of reducing sintering

A D-E hysteresis loop of ferroelectrics known in the art has a square shape when the ferroelectrics are a BaTiO.sub.3 single crystal. Such ferroelectrics are used as a non-linear dielectric element of, for example a pulse generating device. The non-linear dielectric element according to the present invention consists of a polycrystal, which is mainly composed of BaTiO.sub.3 and has the chemical composition expressed by the formula A.sub.y B.sub.z O.sub.3, wherein the molar ratio of y/z ranges from 0.92 to 0.99. The non-linearity is excellent and the temperature dependence of the A.sub.y B.sub.z O.sub.3 composition is considerably low.

Non-linear dielectric element

The invention provides a novel electric power source unit such as a high-speed pulse power source unit built with a pulse-forming circuit and a DC electric power source unit built with a high-frequency voltage-multipler rectifying circuit having high performance in comparison with conventional units. The inventive unit comprises, as a part of the circuit, at least one ceramic capacitor composed of a ceramic dielectric body made of a strontium titanate-based composition unlike the conventional ones in the prior art comprising barium titanate-based ceramic capacitors. Four classes of the preferred compositions are disclosed each containing strontium titanate as the principal component.

Electric power source units

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.

A ceramic dielectric composition is provided including 35 to 93.5% by weight of SrTiO.sub.3, 4 to 40% by weight of Bi.sub.2 O.sub.3, at least 2.5% but less than 60% by weight of TiO.sub.2, and 0.1 to 5.0% by weight, of an alkali metal oxide based on the total amount of SrTiO.sub.3, Bi.sub.2 O.sub.3 and TiO.sub.2. The ceramic dielectric composition has a high dielectric constant and low dielectric loss and exhibits reduced variations of dielectric constant and the dielectric loss with respect to variation of an applied voltage.

Ceramic dielectric composition containing alkali metal 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 .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.

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Akita, Japan

Shinobu Fujiwara