A production method of a dielectric ceramic composition, comprising a main component comprised of barium titanate, a fourth subcomponent comprised of an oxide of R1 (note that R1 is at least one kind selected from a first element group composed of rare earth elements having a value of effective ionic radius for coordination number 9 of less than 108 pm) and a fifth sub component comprised of an oxide of R2 (note that R2 is at least one kind selected from a second element group composed of rare earth elements having a value of effective ionic radius for coordination number 9 of 108 pm to 113 pm); comprising the steps of obtaining a post-reaction material by bringing the main component material reacting with a part of the fourth subcomponent material and/or a part of the fifth subcomponent material, and adding remaining materials of the fourth subcomponent and the fifth subcomponent to be included in the dielectric ceramic composition to the post-reaction material; wherein a ratio M1/M2 of the number of moles M1 of R1 of the fourth subcomponent and the number of moles M2 of R2 of the fifth subcomponent in the finally obtained dielectric ceramic can be balanced even when the dielectric layers are made thin.
Description
BRIEF DESCRIPTION OF DRAWINGS
Below, the present invention will be explained based on an embodiment shown in a drawing.
FIG. 1 is a sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.
Claims
1. A production method of a dielectric ceramic composition, comprising
a main component comprised of barium titanate,a fourth subcomponent comprised of an oxide of R1 (note that R1 is at least one kind selected from a first element group composed of rare earth elements having a value of effective ionic radius for coordination number 9 of less than 108 pm), anda fifth subcomponent comprised of an oxide of R2 (note that R2 is at least one kind selected from a second element group composed of rare earth elements having a value of effective ionic radius for coordination number 9 of 108 pm to 113 pm);comprising the steps ofobtaining a post-reaction material by bringing a material of said main component reacting with a part of a material of said fourth subcomponent and/or a part of a material of said fifth subcomponent to be included in said dielectric ceramic composition in advance, and adding remaining materials of said fourth subcomponent and said fifth subcomponent to be included in said dielectric ceramic composition to said post-reaction material;wherein a ratio M1/M2 of the number of moles M1 of R1 of said fourth subcomponent to the number of moles M2 of R2 of said fifth subcomponent in said finally obtained dielectric ceramic composition satisfies 4<M1/M2≦100.
2. The production method of a dielectric ceramic composition as set forth in claim 1, wherein in said step for obtaining the post-reaction material, the material of said main component and a part of the material of said fourth subcomponent and/or a part of the material of said fifth subcomponent to be included in said dielectric ceramic composition are dispersed as solid solution in advance.
3. The production method of a dielectric ceramic composition as set forth in claim 1, wherein
a content of said fourth subcomponent in the finally obtained dielectric ceramic composition with respect to 100 moles of said main component is 0 to 10 moles (note that 0 is not included) when calculated as a conversion of R1, and a content of said fifth subcomponent in the finally obtained dielectric ceramic composition with respect to 100 moles of said main component is 0 to 2 moles (note that 0 is not included) when calculated as a conversion of R2.
4. The production method of a dielectric ceramic composition as set forth in claim 1, wherein said fourth subcomponent and/or said fifth subcomponent to be brought to react with a material of said main component in advance is 0 to 0.5 mole (note that 0 and 0.5 are not included) when calculated as a conversion of R1 and/or R2 with respect to 100 moles of said main component.
5. The production method of a dielectric ceramic composition as set forth in claim 1, wherein, when assuming that a value of effective ionic radius for coordination number 9 of rare earth elements composing said first element group is r1 and a value of effective ionic radius for coordination number 9 of rare earth elements composing said second element group is r2, said first element group and said second element group are composed so that a ratio (r2/r1) of r1 and r2 satisfies a relationship of 1.007<r2/r1<1.06.
6. The production method of a dielectric ceramic composition as set forth in claim 1, wherein said R1 is at least one kind selected from Y, Ho, Er, Tm, Yb and Lu.
7. The production method of a dielectric ceramic composition as set forth in claim 1, wherein said R2 is at least one kind selected from Dy, Tb, Gd and Eu.
8. The production method of a dielectric ceramic composition as set forth in claim 1, wherein
said dielectric ceramic composition furthermore comprises
a first subcomponent comprised of at least one kind selected from MgO, CaO, BaO and SrO,a second subcomponent comprised of SiO2 mainly and comprised of at least one kind selected from MO (note that M is at least one kind selected from Mg, Ca, Ba and Sr), Li2O and B2O3, anda third subcomponent comprised of at least one kind selected from V2O5, MoO3 and WO3;wherein ratios of respective subcomponents with respect to 100 moles of said main component are
first subcomponent: 0.1 to 5 moles,second subcomponent: 0.1 to 12 moles, andthird subcomponent: 0 to 0.3 mole (note that 0 is not included).
9. The production method of a dielectric ceramic composition as set forth in claim 8, wherein
said dielectric ceramic composition furthermore comprises a sixth subcomponent comprised of MnO and/or Cr2O3, anda ratio of the sixth subcomponent with respect to 100 moles of said main component is 0.05 to 1.0 mole.
10. The production method of a dielectric ceramic composition as set forth in claim 1, wherein a material having an average particle diameter of 0.05 to 0.5 μm is used as a material of said main component.
11. A dielectric ceramic composition produced by the methods as set forth in claim 1.
12. An electronic device having a dielectric layer composed of the dielectric ceramic composition as set forth in claim 11.
Patent Application
20070225154
