Grain boundary-insulated semiconductor ceramic, semiconductor ceramic capacitor, and method for producing semiconductor ceramic capacitor
A grain boundary-insulated semiconductor ceramic contains a SrTiO 3 -based compound as a main component, and a diffusing agent containing a grain boundary insulating agent and a glass component. The grain boundary insulating agent is composed of a material free of lead, the glass component mainly contains a SiO 2 —X 2 O-MO—TiO 2 -based glass material that does not contain boron or lead and in which X represents an alkali metal, and M represents at least one of barium, strontium, and calcium, and the content of the glass component is 3 to 15 parts by weight relative to 100 parts by weight of the grain boundary insulating agent. A component base is composed of the grain boundary-insulated semiconductor ceramic.
1. A grain boundary-insulated semiconductor ceramic comprising:
a strontium titanate as a main component; and
a diffusing agent containing a grain boundary insulating agent and a glass component,
wherein the grain boundary insulating agent comprises a material free of lead,
the glass component mainly comprises a SiO 2 —X 2 O-MO—TiO 2 — based glass material that does not contain boron or lead, and in which X represents an alkali metal, and M represents at least one element selected from barium, strontium, and calcium, and
the content of the glass component is 3 to 15 parts by weight relative to 100 parts by weight of the grain boundary insulating agent.
2. The grain boundary-insulated semiconductor ceramic according to claim 1 , wherein the grain boundary insulating agent contains at least one of bismuth and copper.
3. The grain boundary-insulated semiconductor ceramic according to claim 2 , wherein the content of the grain boundary insulating agent is 0.8 to 1.5 parts by weight relative to 100 parts by weight of the main component.
4. The grain boundary-insulated semiconductor ceramic according to claim 3 , wherein the alkali metal X in the glass component is lithium.
5. The grain boundary-insulated semiconductor ceramic according to claim 1 , wherein the content of the grain boundary insulating agent is 0.8 to 1.5 parts by weight relative to 100 parts by weight of the main component.
6. The grain boundary-insulated semiconductor ceramic according to claim 5 , wherein the alkali metal X in the glass component is lithium.
7. The grain boundary-insulated semiconductor ceramic according to claim 1 , wherein the alkali metal X in the glass component is lithium.
8. The grain boundary-insulated semiconductor ceramic according to claim 1 , wherein the grain boundary insulating agent contains bismuth and copper.
9. The grain boundary-insulated semiconductor ceramic according to claim 1 , wherein the strontium titanate contains at least one of Ba, Ca and a rare earth element.
10. The grain boundary-insulated semiconductor ceramic according to claim 9 , wherein the rare earth element is Y.
11. A semiconductor ceramic capacitor comprising a component base comprising the grain boundary-insulated semiconductor ceramic according to claim 1 .
12. The semiconductor ceramic capacitor according to claim 11 ,
wherein the component base has a tubular shape, and
has an electrode on each of an inner peripheral surface and an outer peripheral surface of the component base.
13. A semiconductor ceramic capacitor comprising a component base comprising the grain boundary-insulated semiconductor ceramic according to claim 4 .
14. The semiconductor ceramic capacitor according to claim 13 ,
wherein the component base has a tubular shape, and
has an electrode on each of an inner peripheral surface and an outer peripheral surface of the component base.
15. A semiconductor ceramic capacitor comprising a component base comprising the grain boundary-insulated semiconductor ceramic according to claim 8 .
16. The semiconductor ceramic capacitor according to claim 15 ,
wherein the component base has a tubular shape, and
has an electrode on each of an inner peripheral surface and an outer peripheral surface of the component base.
17. A method for producing a semiconductor ceramic capacitor, comprising the steps of:
providing a reducing atmosphere sintered body which comprising strontium and titanium;
providing a grain boundary insulating agent comprising a material free of lead and a glass component comprising a SiO 2 —X 2 O-MO—TiO 2 -based glass material that does not contain boron or lead and in which X represents an alkali metal, and M represents at least one element selected from barium, strontium, and calcium; and
preparing a component base by performing a heat treatment in an air atmosphere while mixing and stirring the sintered body with the grain boundary insulating agent and the glass component.
18. The method according to claim 17 ,
wherein the sintered body has a tubular shape, and
the method further comprises forming an electrode on each of an inner peripheral surface and an outer peripheral surface of the component base by a plating process.
19. The method according to claim 17 wherein the amount of the glass component is 3 to 15 parts by weight relative to 100 parts by weight of the grain boundary insulating agent.