Murata Manufacturing Co., Ltd.

Tomomi Koga

Hiroyuki Wada

Kohei Shimada

Sui Uno

Tomotaka Hirata

Hitoshi Nishimura

Hiroki Awata

Kenji Takagi

Shoichiro Suzuki

Koichi Banno

Toshikazu Takeda

Megumi Morita

A multilayer ceramic capacitor includes a laminated body including an inner layer portion including ceramic dielectric layers and internal electrodes, and outer layer portions including ceramic dielectric layers. External electrodes connected to the internal electrodes are provided on both ends of the laminated body. The main constituent of the inner layer portion is a perovskite-type compound represented by ABO. The outer layer portions include first outer layers and second outer layers respectively containing oxides that differ from each other in main constituents, and boundary reaction layers are provided between the first outer layers and the second outer layers. First ceramic dielectric layers outside the boundary reaction layers differ in color from second ceramic dielectric layers inside the boundary reaction layers.

Multilayer ceramic capacitor

A laminated ceramic capacitor having a laminated body composed of a plurality of ceramic layers for inner layers; a plurality of internal electrodes at the interfaces between the plurality of ceramic layers for inner layers; and a plurality of ceramic layers for outer layers, provided on the top and bottom so as to sandwich the plurality of ceramic layers for inner layers. The ceramic layers for inner layers are composed of a material containing a multiple oxide including an alkaline-earth metal. The ceramic layers for outer layers respectively have TiOceramic layers containing TiOas their main constituent for certain layers including the outermost layers, and multiple oxide ceramic layers containing a multiple oxide including an alkaline-earth metal for the other layers.

Laminated ceramic capacitor

A multilayer ceramic capacitor includes a ceramic main body including an inner layer portion including third ceramic layers and a plurality of inner electrodes arranged at interfaces between the third ceramic layers, and first and second outer layer portions respectively including first and second ceramic layers, the first and second ceramic layers being arranged vertically so as to sandwich the inner layer portion. The third ceramic layers and the first and second outer layer portions contain a perovskite-type compound represented by ABOwhere A contains one or more of Ba, Sr, and Ca, B contains one or more of Ti, Zr, and Hf, and O represents oxygen) as a main component. Where a rare-earth element concentration (C) in the third ceramic layers is compared to a rare-earth element concentration (C) in outermost layer portions including at least outermost surfaces of the first and second outer layer portions, C&#x3e;C(inclusive of C=0).

A dielectric ceramic that includes a sintered body of BaTiObased ceramic grains, in which the ceramic grains each include a shell part as a surface layer part and a core part inside the shell part. The ceramic grains contain, as accessory constituents, R (R, which is a rare-earth element, is at least one selected from the group consisting of Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Y) and M (M is at least one selected from the group consisting of Mg, Mn, Ni, Co, Fe, Cr, Cu, Al, Mo, W, and V). R and M are present in the shell part of the ceramic grain, and concentrations of R and M contained in the shell part are increased from a grain boundary toward the core part.

Dielectric ceramic and laminated ceramic capacitor using the same

A dielectric ceramic with stable insulation properties even after calcination under a reducing atmosphere, as is preferred for a laminated ceramic capacitor, is a CaTiOcomposition containing Sn. It is preferable for the dielectric ceramic to contain, as its main component, (CaBaSn)TiO(0&#x2266;x&#x3c;0.2, 0.01&#x2266;y&#x3c;0.2) with a solution of Sn at the B site.

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Nagaokakyo, Japan

Tomomi Koga