Dielectric composition, dielectric element, electronic component and multi-layer electronic component

1. A dielectric composition comprising:

particles having a perovskite crystal structure including at least Bi, Na, Sr and Ti,

wherein at least some of the particles have a core-shell structure comprising a core portion and a shell portion, and

wherein a content of Bi present in the core portion is at least 1.2 times a content of Bi present in the shell portion.

2. The dielectric composition according to claim 1 , wherein S 1 :S 2 =1:99-20:80 in a cross section of the dielectric composition, and wherein S 1 is a mean cross-sectional area of the core portions and S 2 is a mean cross-sectional area of the shell portions.

3. The dielectric composition according to claim 1 , wherein a total cross-sectional area of the core portions is 0.1%-15% with respect to the dielectric composition as a whole, in a cross section of the dielectric composition.

4. The dielectric composition according to claim 1 , wherein 0.125≤α≤2.00, where α is a molar ratio of Bi with respect to Sr in the dielectric composition.

5. The dielectric composition according to claim 1 , further comprising at least one element selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Ba, Ca, Mg and Zn.

6. A dielectric element comprising the dielectric composition according to claim 1 .

7. An electronic component comprising:

a dielectric layer having the dielectric composition according to claim 1 .

8. A laminated electronic component comprising:

a laminated portion formed by alternately laminating an internal electrode layer and a dielectric layer comprising the dielectric composition according to claim 1 .

9. A single-layer ceramic capacitor comprising:

a disc-shaped dielectric body comprising the dielectric composition according to claim 1 ; and

a pair of electrodes, wherein the electrodes are located on both surfaces of the dielectric body.

10. The single-layer ceramic capacitor according to claim 9 , wherein a material of the electrodes comprises Cu.

11. A laminated ceramic capacitor comprising:

a capacitor element main body having a structure in which dielectric layers comprising the dielectric composition according to claim 9 and internal electrode layers are alternately stacked; and

a pair of terminal electrodes which are respectively conductively connected with the internal electrode layers alternately arranged inside the main body and which are located at both ends of the main body.

12. The laminated ceramic capacitor according to claim 11 , wherein a material of the internal electrode layers comprises Cu.

13. The laminated ceramic capacitor according to claim 11 , wherein the internal electrode layers comprise a base metal as a conductive material.

14. The laminated ceramic capacitor according to claim 11 , wherein the internal electrode layers comprise Cu alloy as a conductive material.

15. The laminated ceramic capacitor according to claim 11 , wherein the terminal electrodes comprise a conductive material having Cu as a main component thereof.

16. A method for producing a laminated ceramic capacitor, the method comprising:

preparing a green chip using a sheet method or a printing method employing a paste for dielectric layers and a paste for internal electrodes, wherein the paste for the dielectric layers is an organic paint comprising a mixture of a dielectric starting material and an organic vehicle or wherein the paste for the dielectric layers is an aqueous paint comprising a mixture of a dielectric starting material and an aqueous vehicle;

performing a debinding treatment;

baking the green chip thereby forming a main body;

printing or transcribing external electrodes on the main body; and

backing the main body,

wherein starting material is selected such that a dielectric composition of the laminated ceramic capacitor comprises particles having a perovskite crystal structure including at least Bi, Na, Sr and Ti,

wherein at least some of the particles have a core-shell structure comprising a core portion and a shell portion, and

wherein a content of Bi present in the core portion is at least 1.2 times a content of Bi present in the shell portion.

17. The method according to claim 16 , wherein the paste for the internal electrodes is prepared by mixing a conductive material comprising Au, Pt, Ag, Ag—Pd alloy, Cu or Ni, or various types of oxide which form the conductive material after baking, or organometallic compounds, or resonates with the organic vehicle, and wherein a paste for the external electrodes is prepared in the same way as the paste for the internal electrodes.