Ceramic capacitor and method for the preparation thereof

Claim 2

A ceramic capacitor having a dielectric layer composed of one or more than one dielectric ceramic composition and two or more than two internal electrodes so disposed as to interpose the dielectric layer, wherein: the dielectric ceramic composition is composed of a sintered body of ceramic particles having crystal grains with a core section composed mainly of BaTiO 3 and a shell portion composed of crystal grains of BaTiO 3 in the form of a solid solution comprising an oxide of one or more than one elements M selected from the group consisting of Mg, Ca, Sr, and Zn, and on oxide as represented by R 2 O 3 , wherein R is one or more than on element selected from the group consisting of Sc, Y, Gd, Dy, Ho, Er, Yb, Tb, Tm and Lu and optionally ZrO 2 , said ceramic particles having a structure as shown in the microphotograph of FIG. 1, with streaks domain walls in the core section, said shell sections having M and R in the crystal grains of BaTiO 3x in the shell, with M and R components in the shell being substantially uniformly distributed.

Claim 3

A ceramic capacitor as claimed in claim 1, wherein the shell section of the ceramic particle is composed of ZnO 2 in the form of a solid solution.

Claim 4

A ceramic capacitor as claimed in claim 1, wherein the internal electrode is composed of material containing Ni as a major component.

Claim 5

The ceramic capacitor of claim 1, wherein the core section of the crystal grain is composed mainly of BaTiO 3 and the shell section is composed of BaTiO 3 and a solid solution of ZrO 2 .

Claim 6

A process for the preparation of a ceramic capacitor comprising: a step of preparing powder of raw material as basic component; a step of calcining the powder of raw material as the basic component at a predetermined temperature; a step of forming a slurry by mixing the calcined raw material powder with powder of an additive component and an organic binder; a step of formulating the slurry into a sheet form, thereby forming a non-sintered ceramic sheet; a step of yielding a laminated body by forming a conductive paste film so as to interpose the non-sintered ceramic sheet; a step of baking the laminated body in a non-oxidative atmosphere; and a step of subjecting the laminated body to heat treatment in an oxidative atmosphere; wherein the basic component comprises BaTiO 3 as a major component, one or more than one oxide selected from MgO, CaO, SrO and ZnO, an oxide as represented by R 2 O 3 , wherein R is one or more than one element selected from Sc, Y, Gd, Dy, Ho, Er, Yb, Tb, Tm and Lu, and BaO and/or TiO 2 so added as to amount to 1.00≦k≦1.04, wherein k is a ratio by mole of (Ba+Mg+Ca+Sr+Zn) to (Ti+R); and wherein an additive component comprises Li 2 O-SiO 2 -MeO or B 2 O 3 -SiO 2 -MeO, wherein Me is one or more than one element selected from Ba, Ca, Sr, Mg and Zn.

Claim 7

A process for the preparation of a ceramic capacitor comprising: a step of preparing powder of raw material as basic component; a step of calcining the powder of raw material as the basic component at a predetermined temperature; a step of forming a slurry by mixing the calcined raw material powder with powder of an additive component and an organic binder; a step of formulating the slurry into a sheet form, thereby forming a non-sintered ceramic sheet; a step of yielding a laminated body by forming a conductive paste film so as to interpose the non-sintered ceramic sheet; a step of baking the laminated body in a non-oxidative atmosphere; and a step of subjecting the laminated body to heat treatment in an oxidative atmosphere; wherein the basic component comprises BaTiO 3 as a major component, one or more than one oxide selected from MgO, CaO, SrO and ZnO, an oxide as represented by R 2 O 3 , wherein R is one or more than one element selected from Sc, Y, Gd, Dy, Ho, Er, Yb, Tb, Tm and Lu, and BaO and/or TiO 2 so added as to amount to 1.00≦k≦1.04, wherein k is a ratio by mole of (Ba+Mg+Ca+Sr+Zn) to (Ti+R); and wherein an additive component comprises Li 2 O-SiO 2 -MeO or B 2 O 3 -SiO 2 -MeO, wherein Me is one or more than one element selected from Ba, Ca, Sr, Mg and Zn.

Claim 8

A method as claimed in claim 5, wherein the conductive paste is formed with material containing Ni as a major component.

Claim 9

A method as claimed in claim 5, wherein the additive component comprises Cr 2 O 3 and/or Al 2 O 3 .

Claim 10

A process for the preparation of a ceramic capacitor comprising: a step of preparing powder of raw material as a first basic component; a step of calcining the powder of raw material as the first basic component at a predetermined temperature; a step of forming a slurry by mixing the calcined first basic component with powder of raw material as a second basic component, an additive component and an organic binder; a step of formulating the slurry into a sheet form, thereby forming a non-sintered ceramic sheet; a step of yielding a laminated body by forming a conductive paste film so as to interpose the non-sintered ceramic sheet; a step of baking the laminated body in a non-oxidative atmosphere; and a step of subjecting the laminated body to heat treatment in an oxidative atmosphere; wherein the first basic component comprises BaTiO 3 as a major component, one or more than one oxide selected from MgO, CaO, SrO and ZnO, an oxide as represented by R 2 O 3 , wherein R is one or more than one element selected from Sc, Y, Gd, Dy, Ho, Er, Yb, Tb, Tm and Lu, and BaO and/or TiO 3 so added as to amount to 1.00≦k≦1.04, wherein k is a molar ratio of (Ba+Mg+Ca+Sr+Zn) to (Ti+R); wherein the second basic component comprises CaZrO 3 and/or BaZrO 3 ; and wherein an additive component comprises Li 2 O-SiO 2 -MeO or B 2 O 3 -SiO 2 -MeO, wherein Me is one or more than one element selected from Ba, Ca, Sr, Mg and Zn.

Claim 11

A process for the preparation of a ceramic capacitor comprising: a step of preparing powder of raw material as a first basic component; a step of calcining the powder of raw material as the first basic component at a predetermined temperature; a step of forming a slurry by mixing the calcined first basic component with powder of raw material as a second basic component, an additive component and an organic binder; a step of formulating the slurry into a sheet form, thereby forming a non-sintered ceramic sheet; a step of yielding a laminated body by forming a conductive paste film so as to interpose the non-sintered ceramic sheet; a step of baking the laminated body in a non-oxidative atmosphere; and a step of subjecting the laminated body to heat treatment in an oxidative atmosphere; wherein the first basic component comprises BaTiO 3 as a major component, one or more than one oxide selected from MgO, CaO, SrO and ZnO, an oxide as represented by R 2 O 3 , wherein R is one or more than one element selected from Sc, Y, Gd, Dy, Ho, Er, Yb, Tb, Tm and Lu, and BaO and/or TiO 3 so added as to amount to 1.00≦k≦1.04, wherein k is a molar ratio of (Ba+Mg+Ca+Sr+Zn) to (Ti+R); wherein the second basic component comprises CaZrO 3 and/or BaZrO 3 ; and wherein an additive component comprises Li 2 O-SiO 2 -MeO or B 2 O 3 -SiO 2 -MeO, wherein Me is one or more than one element selected from Ba, Ca, Sr, Mg and Zn.

Claim 12

A method as claimed in claim 8, wherein the conductive paste is formed with material containing Ni as a major component.

Claim 13

A method as claimed in claim 8, wherein the additive component comprises Cr 2 O 3 and/or Al 2 O 3 .

Claim 14

A dielectric ceramic composition composed of a sintered body of ceramic particles having an inner core section and an outer shell section, the core being composed mainly of BaTiO 3 and the shell section being composed of BaTiO 3 and a solid solution of one or more oxides, said composition having a structure as shown in the microphotograph of FIG. 1.

Claim 15

A dielectric ceramic composition composed of a sintered body of ceramic particles having an inner core section and an outer shell section, the core being composed mainly of BaTiO 3 and the shell section being composed of BaTiO 3 and a solid solution of one or more oxides, said composition having a structure as shown in the microphotograph of FIG. 1.