A method for producing an alumina sintered body, including: a step of applying an alkaline earth metal compound onto a surface of an alumina raw material which is an unsintered alumina compact or an alumina sintered body; and a step of subjecting the alumina raw material to which the alkaline earth metal compound has been applied to heat treatment at a temperature of 1200 C. or more for 5 minutes or more and 300 minutes or less.

The present invention provides a ceramic composition, comprising a primary mixture and a secondary mixture, wherein the primary mixture comprises a first primary ingredient powder and a second primary ingredient powder, and the first primary ingredient powder comprises BaTiO.sub.3, the second primary ingredient powder comprises any of SrTiO.sub.3, Ba.sub.0.95Ca.sub.0.05TiO.sub.3, BaZr.sub.0.1Ti.sub.0.9O.sub.3 or a combination thereof, and the secondary mixture comprises a rare earth oxide, a silicon oxide and an alkaline-earth metal oxide. The present invention further provides a ceramic sintered body obtained by sintering the ceramic composition, and a capacitor comprising the ceramic sintered body and a method for manufacturing the same; wherein the capacitor satisfies EIA-X8R specification, and has a high dielectric constant.

A method of manufacturing a multilayer ceramic electronic component includes: preparing a dielectric magnetic composition including base material powder particles including BaTi.sub.2O.sub.5 or (Ba.sub.(1-x)Ca.sub.x)Ti.sub.2O.sub.5 (0x<0.1), the base material powder particles having surfaces coated with one or more of Mg, Mn, V, Ba, Si, Al and a rare earth metal; preparing ceramic green sheets using dielectric slurry including the dielectric magnetic composition; applying an internal electrode paste to the ceramic green sheets; preparing a green sheet laminate by stacking the ceramic green sheets to which the internal electrode paste is applied; and preparing a ceramic body including dielectric layers and a plurality of first and second internal electrodes arranged to face each other with each of the dielectric layers interposed therebetween by sintering the green sheet laminate.

A method for producing an alumina sintered body, including: a step of applying an alkaline earth metal compound onto a surface of an alumina raw material which is an unsintered alumina compact or an alumina sintered body; and a step of subjecting the alumina raw material to which the alkaline earth metal compound has been applied to heat treatment at a temperature of 1200 C. or more for 5 minutes or more and 300 minutes or less.

An alumina sintered body including an inner layer in which alumina crystal grains contained have an average aspect ratio of 1.0 to 2.0 and an outer layer which covers at least a part of the inner layer from outside and in which alumina crystal grains contained have an average aspect ratio of more than 2.0, the alumina sintered body being free from silicon except unavoidable impurities.

A method of manufacturing a multilayer ceramic electronic component includes: preparing a dielectric magnetic composition including base material powder particles including BaTi.sub.2O.sub.5 or (Ba.sub.(1-x)Ca.sub.x)Ti.sub.2O.sub.5 (0x<0.1), the base material powder particles having surfaces coated with one or more of Mg, Mn, V, Ba, Si, Al and a rare earth metal; preparing ceramic green sheets using dielectric slurry including the dielectric magnetic composition; applying an internal electrode paste to the ceramic green sheets; preparing a green sheet laminate by stacking the ceramic green sheets to which the internal electrode paste is applied; and preparing a ceramic body including dielectric layers and a plurality of first and second internal electrodes arranged to face each other with each of the dielectric layers interposed therebetween by sintering the green sheet laminate.

A multilayer ceramic capacitor includes: a ceramic body including dielectric layers and first and second internal electrodes disposed to face each other with respective dielectric layers interposed therebetween; and first and second external electrodes disposed on an external surface of the ceramic body, wherein the dielectric layer contains a barium titanate-based powder particle having a core-shell structure including a core and a shell around the core, the shell having a structure in which titanium is partially substituted with an element having the same oxidation number as that of the titanium in the barium titanate-based powder particle and having an ionic radius different from that of the titanium in the barium titanate-based powder particle, and the shell covers at least 30% of a surface of the core.

Disclosed is a composite abrasive with hard core and soft shell, comprising hard abrasive core with grain diameter in a range of 0.11 m and a soft oxide shell with thickness in a range of 5100 nm, the grain size of the oxide of the soft oxide shell is in a range of 520 nm, the composite abrasive is obtained from aqueous solution of oxide inorganic salt precursor and the hard abrasive by dispersing, constant temperature reflux hydrolyzing, solid-liquid separating, washing and drying. The component abrasive with hard core and soft shell of the present invention can improve the manufacturing efficiency and the surface quality during the ultraprecise manufacturing of the sapphire substrate.

A multilayer ceramic capacitor includes: a ceramic body including dielectric layers and first and second internal electrodes disposed to face each other with respective dielectric layers interposed therebetween; and first and second external electrodes disposed on an external surface of the ceramic body, wherein the dielectric layer contains a barium titanate-based powder particle having a core-shell structure including a core and a shell around the core, the shell having a structure in which titanium is partially substituted with an element having the same oxidation number as that of the titanium in the barium titanate-based powder particle and having an ionic radius different from that of the titanium in the barium titanate-based powder particle, and the shell covers at least 30% of a surface of the core.

A multilayer ceramic electronic component includes: a body part including dielectric layers and internal electrodes disposed to face each other with respective dielectric layers interposed therebetween; and external electrodes disposed on an outer surface of the body part and electrically connected to the internal electrodes. The dielectric layer includes grains including: a semiconductive or conductive grain core region containing a base material represented by ABO.sub.3, where A is at least one of Ba, Sr, and Ca, and B is at least one of Ti, Zr, and Hf, and a doping material including a rare earth element; and an insulating grain shell region enclosing the grain core region.