Dielectric ceramic composition and the production method

Abstract

A dielectric ceramic composition, comprising a main component including a dielectric oxide, and a sintering auxiliary comprising a first component including an oxide of Li and a second component including an oxide of M1 (note that M1 is at least one kind of element selected from group V elements and VI group elements): wherein said dielectric ceramic composition comprises a plurality of dielectric particles and crystal grain boundaries existing between said dielectric particles next to each other; concentration of M1 element becomes lower from a particle surface to inside thereof in the plurality of dielectric particles; and when assuming that a particle diameter of said dielectric particles is D and a content ratio of the M1 element at said crystal grain boundaries is 100%, a content ratio of the M1 element at a depth T50, where a depth from the particle surface is 50% of said particle diameter D, is 3 to 55%.

Description

BRIEF DESCRIPTION OF DRAWINGS

These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the attached drawings, in which:

FIG. 1 is a sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention;

FIG. 2 is an enlarged sectional view of a key part of a dielectric layer 2 shown in FIG. 1; and

FIG. 3 is a conceptual view for explaining the inner structure of a dielectric particle.

Claims

1. A dielectric ceramic composition, comprising a main component including a dielectric oxide, anda sintering auxiliary comprising a first component including an oxide of Li and a second component including an oxide of M1 (note that M1 is at least one kind of element selected from group V elements and VI group elements): whereinsaid dielectric ceramic composition comprises a plurality of dielectric particles and crystal grain boundaries existing between said dielectric particles next to each other;concentration of M1 element becomes lower from a particle surface to inside thereof in the plurality of dielectric particles; andwhen assuming that a particle diameter of said dielectric particles is D and a content ratio of the M1 element at said crystal grain boundaries is 100%, a content ratio of the M1 element at a depth T50, where a depth from the particle surface is 50% of said particle diameter D, is 3 to 55%.

2. The dielectric ceramic composition as set forth in claim 1, wherein a content ratio of the M1 element at a depth T30, where a depth from the particle surface is 30% of said particle diameter D, is 5 to 60% with respect to a content ratio of the M1 element being 100% at said crystal grain boundaries.

3. The dielectric ceramic composition as set forth in claim 1, wherein a content ratio of the M1 element at a depth T15 where a depth from the particle surface is 15% of said particle diameter D, is 15 to 70% with respect to a content ratio of the M1 element being 100% at said crystal grain boundaries.

4. The dielectric ceramic composition as set forth in claim 1, wherein said dielectric oxide included as a main component is expressed by a composition formula of {(Ba(1-x-y) Cax Sry)O}A (Ti(1-z) Zrz)B O2, and“A”, “B”, “x”, “y” and “z” in said composition formula satisfy 0.75≦A/B≦1.04, 0≦×≦0.9, 0≦y≦0.5 and 0<z<1.

5. The dielectric ceramic composition as set forth in claim 1, wherein said sintering auxiliary further comprises a third component including a compound of M2 (note that M2 is at least one selected from Ba, Ca, Sr, Mg, Mn, B, Al and Zn), anda fourth component including an oxide of Si and/or a compound to be an oxide of Si when being fired.

6. A production method of a dielectric ceramic composition comprising a main component including a dielectric oxide and a sintering auxiliary having a first component including an oxide of Li and a second component including an oxide of M1 (note that M1 is at least one kind of element selected from group V elements and VI group elements), comprising the steps of: preparing a dielectric ceramic composition material to be said dielectric ceramic composition after being fired, andfiring said prepared dielectric ceramic composition material;wherein a temperature raising rate at the time of raising the temperature to a holding temperature at firing is 300 to 700° C./hour in said firing step.

7. The production method of the dielectric ceramic composition as set forth in claim 6, wherein a firing holding temperature is 900 to 1100° C. in said firing step.

8. The production method of the dielectric ceramic composition as set forth in claim 6, wherein temperature holding time is 0 to 0.5 hour in said firing step.

9. The production method of the dielectric ceramic composition as set forth in claim 6, wherein said dielectric oxide included as a main component is expressed by a composition formula of {(Ba(1-x-y) Cax Sry)O}A (Ti(1-z) Zrz)B O2, and“A”, “B”, “x”, “y” and “z” in said composition formula satisfy 0.75≦A/B≦1.04, 0≦x≦0.9, 0≦y≦0.5 and 0<z<1.

10. The production method of the dielectric ceramic composition as set forth in claim 6, wherein said sintering auxiliary further comprises a third component including a compound of M2 (note that M2 is at least one selected from Ba, Ca, Sr, Mg, Mn, B, Al and Zn), anda fourth component including an oxide of Si and/or a compound to be an oxide of Si when being fired.