Murata Manufacturing Co., Ltd.

Toshihiro Okamatsu

Harunobu Sano

Tomoyuki Nakamura

Noriyuki Inoue

Kotaro Hata

Kenji Hori

Hiroyasu Konaka

Akira Kato

Hiroyuki Wada

Takashi Hiramatsu

Hitoshi Nishimura

Takafumi Okamoto

Akihiro Tsuru

Shinya Isota

Toru Nakanishi

A monolithic ceramic capacitor that contains a perovskite compound including Ba and Ti and at least one type of element selected from Gd, Tb, and Dy, and contains elements selected from Y, Si, Mn, Mg, and Zr. The content a of at least one element selected from Gd, Tb, and Dy satisfies 0.2&#x2264;a&#x2264;0.8, the content b of Y satisfies 0.0&#x2264;b&#x2264;0.5, the content c of Si satisfies 0.0&#x2264;c&#x2264;2.5, the content d of Mn satisfies 0.0&#x2264;d&#x2264;0.25, the content e of Mg satisfies 0.0&#x2264;e&#x2264;1.2, the content f of Zr satisfies 0.0&#x2264;f&#x2264;0.5, and the molar ratio m of the content of Ba/(f+the content of Ti) satisfies 0.99&#x2264;m&#x2264;1.01, where the total content of Ti is 100 parts by mole.

Monolithic ceramic capacitor and method for manufacturing the same

Provided is a dielectric ceramic which exhibits desired high temperature load resistance characteristics even under a high electric field strength on the order of 15 kV/mm. The dielectric ceramic contains, as its main constituent, a perovskite compound represented by the general formula (BaCaSrGd)(TiZrHfMgZnMn)O, 0&#x2266;h&#x2266;0.03, 0&#x2266;i&#x2266;0.03; 0.042&#x2266;m&#x2266;0.074; 0.94&#x2266;k&#x2266;1.075; 0&#x2266;(y+j)&#x2266;0.05; 0.015&#x2266;n&#x2266;0.07; 0&#x2266;o&#x2266;0.04; 0&#x2266;p&#x2266;0.05; and 1.0&#x3c;m/(n+o)&#x3c;4.3. The dielectric ceramic can be used advantageously as a material for a dielectric ceramic layer provided in a laminated ceramic capacitor.

Dielectric ceramic and laminated ceramic capacitor

A laminated ceramic capacitor which has a dielectric ceramic with a high dielectric constant and has excellent reliability against changes in temperature and mechanical shocks, even when dielectric ceramic layers are reduced in thickness employs a dielectric ceramic containing (BaCa)TiO(where 0.045&#x2266;x&#x2266;0.15 and 0.98&#x2266;y&#x2266;1.05) as its main constituent and containing ReO(where Re is at least one of Gd, Dy, Ho, Yb, and Y), MgO, MnO, VO, and SiOas accessory constituents, which is represented by the general formula: 100(BaCa)TiO+aReO+bMgO+cMnO+dVO+eSiO, and satisfies each of the following conditions: 0.65&#x2266;a&#x2266;1.5; 0.98&#x2266;y&#x2266;1.05; 0.15&#x2266;b&#x2266;2.0; 0.4&#x2266;c&#x2266;1.5; 0.02&#x2266;d&#x2266;0.25; and 0.2&#x2266;e&#x2266;3.0.

A dielectric ceramic contains a barium titanate compound oxide as a main component; at least one rare earth element R selected from Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; Mg; and Ni, such that a crystalline compound oxide containing the rare earth element R, Ni, and Ti as main components is present. Dielectric ceramic layers are made of the dielectric ceramic. Accordingly, even when a higher electric field is continuously applied under a high-temperature atmosphere for a long time, high reliability can be ensured.

Dielectric ceramic, method of producing the same, and monolithic ceramic capacitor

A dielectric ceramic is provided having a high relative dielectric constant, and in the case in which it is used for a multilayer ceramic capacitor, high insulating properties and superior reliability can be obtained even when the thickness of a dielectric ceramic layer is decreased. The dielectric ceramic used for forming the dielectric ceramic layer of a multilayer ceramic capacitor has a composition represented by 100 (BaCaSrGd)(TiZrHfMg)O+pMnO+qSiO+rCuO, in which 0.995&#x2266;k&#x2266;1.010, 0&#x2266;w&#x3c;0.04, 0&#x2266;x&#x2266;0.04, 0&#x2266;y&#x2266;0.10, 0&#x2266;z&#x2266;0.05, 0.015&#x2266;m&#x2266;0.035, 0.015&#x2266;n&#x2266;0.035, 0.01&#x2266;p&#x2266;1.0, 0.5&#x2266;q&#x2266;2.5, and 0.01&#x2266;r&#x2266;5.0. In addition, a is a value selected with respect to the deviation from 3 so that the primary component is electrically neutral.

Dielectric ceramic and multilayer ceramic capacitor

A dielectric ceramic is obtained by the steps of obtaining a reaction product composed of a barium titanate base composite oxide represented by the general formula (BaCaSrGd)k(TiZrHfMg)O, in which 0.995&#x2266;k&#x2266;1.015, 0&#x2266;h&#x2266;0.03, 0&#x2266;i&#x2266;0.03, 0.015&#x2266;m&#x2266;0.035, 0&#x2266;y&#x3c;0.05, 0&#x2266;j&#x3c;0.05, 0&#x2266;(y+j)&#x3c;0.05, and 0.015&#x2266;n&#x2266;0.035 hold; mixing less than 1.5 moles of Ma (Ba or the like), less than 1.0 mole of Mb (Mn or the like), and 0.5 to 2.0 moles of Mc (Si or the like) with respect to 100 moles of the reaction product; and firing the mixture thus obtained. This dielectric ceramic has superior humidity resistance, satisfies the F characteristic of the JIS standard and the Y5V characteristic of the EIA standard, has a relative dielectric constant of 9,000 or more, and has superior high-temperature reliability.

Dielectric ceramic, manufacturing method therefor, and multilayer ceramic capacitor

A dielectric ceramic has a ceramic structure of crystal grains and grain boundaries between the crystal grains. The crystal grains are of a main component represented by the formula ABOand an additive containing a rare earth element wherein A is at least one of barium, calcium, and strontium, barium being an essential element, and B is at least one of titanium, zirconium, and hafnium, titanium being an essential element. The average rare earth element concentration in the interior of the crystal grains is about 50% or less the average rare earth element concentration at the grain boundaries. Furthermore, about 20% to 70% of the crystal grains have a rare earth element concentration in the center of the crystal grain of at least about 1/50 the maximum rare earth element concentration in a region extending inward from the surface by a distance corresponding to about 5% of the diameter of the crystal grain.

Dielectric ceramic, methods for making and evaluating the same, and monolithic ceramic electronic component

A dielectric ceramic has a ceramic structure of crystal grains and grain boundaries between the crystal grains. The crystal grains are of a main component represented by the formula ABO and an additive containing a rare earth element wherein A is at least one of barium, calcium, and strontium, barium being an essential element, and B is at least one of titanium, zirconium, and hafnium, titanium being an essential element. The average rare earth element concentration in the interior of the crystal grains is about 50% or less the average rare earth element concentration at the grain boundaries. Furthermore, about 20% to 70% of the crystal grains have a rare earth element concentration in the center of the crystal grain of at least about {fraction (1/50)} the maximum rare earth element concentration in a region extending inward from the surface by a distance corresponding to about 5% of the diameter of the crystal grain.

A dielectric ceramic composition comprises a compound oxide comprising barium titanate Ba TiO as a major component and RO , CaO, MgO, and SiO , as accessory components, wherein R is at least one element selected from the group consisting of Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb, wherein the compound oxide satisfies the following relationship: 100Ba TiO &plus;aRO &plus;bCaO&plus;cMgO&plus;dSiO , wherein, on a molar basis, 0.990&lE;m&lE;1.030, 0.5&lE;a&lE;6.0, 0.10&lE;b&lE;5.00, 0.010&lE;c<1.000, and 0.05 &lE;d<2.00. The dielectric ceramic composition satisfies the B characteristic defined by the Japanese Industrial Standard (JIS) and the X7R characteristic defined by the EIA standard with respect to dependence of electrostatic capacitance on temperature, and has a large CR product of the insulation resistance and the electrostatic capacitance. A monolithic ceramic capacitor which includes thin dielectric layers composed of this dielectric ceramic composition is highly reliable.

Dielectric ceramic composition and monolithic ceramic capacitor

A ceramic capacitor has a dielectric ceramic layer and at least one pair of electrodes. The dielectric ceramic layer has a primary phase and secondary phases, and the size of the secondary phases in the thickness direction of the dielectric ceramic layer is not more than about one-third of the thickness of the dielectric ceramic layer. A method for making the ceramic capacitor includes the steps of mixing compounds constituting secondary phases in a primary phase of a dielectric ceramic, annealing and then pulverizing the mixture to prepare a raw material for the secondary phases, mixing the raw material for the secondary phases with other materials for the dielectric ceramic shaping and sintering the mixture to form a dielectric ceramic, and forming electrodes on the dielectric ceramic. The ceramic capacitor has high insulation resistance, superior load characteristics at high temperatures or high humidity and high weather resistance, even when sintered in a reducing atmosphere.

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Moriyama, Japan

Toshihiro Okamatsu