Beta-alumina-based sintered compact and its production method
View Patent ↗To provide a dense beta-alumina-based sintered compact having a high ionic conductivity as a solid electrolyte by firing at a low temperature to suppress the volatilization of Na 2 O and its production method. By adding RNbO 3 which is a material having a low melting point to a beta-alumina powder, followed by firing, it is possible to obtain a beta-alumina-based sintered compact having a low firing temperature and containing, as the main component, dense β″ alumina crystals which are free from anomalous grain growth during the firing process.
1. A beta-alumina-based sintered compact, comprising:
a beta-alumina crystalline phase having Na 2 O and Al 2 O 3 as main components; and
an RNbO 3 crystalline phase;
wherein R is at least one element selected from the group consisting of Li, Na, and K.
2. The beta-alumina-based sintered compact according to claim 1 , wherein the beta-alumina crystalline phase comprises a β″ alumina crystalline phase.
3. The beta-alumina-based sintered compact according to claim 1 , wherein R is Na.
4. The beta-alumina-based sintered compact according to claim 1 , comprising NiO as a component.
5. The beta-alumina-based sintered compact according to claim 4 , wherein a chemical composition of the beta-alumina-based sintered compact, based on oxides, is:
from 8 to 15 mass % of Na 2 O;
from 5 to 30 mass % of Nb 2 O 5 ;
from 1 to 10 mass % of NiO; and
a remainder of Al 2 O 3 .
6. A method for producing the beta-alumina-based sintered compact as defined in claim 1 , comprising:
mixing a beta-alumina powder and an RNbO 3 powder; and
molding and firing the mixture;
wherein R is at least one element selected from the group consisting of Li, Na, and K.
7. The method for producing the beta-alumina-based sintered compact according to claim 6 , wherein firing the mixture comprises firing at a temperature of less than 1450° C.
8. The method for producing the beta-alumina-based sintered compact according to claim 6 , wherein the beta-alumina powder comprises β″ alumina.
9. The method for producing the beta-alumina-based sintered compact according to claim 6 , wherein R is Na.
10. The method for producing the beta-alumina-based sintered compact according to claim 6 , wherein the beta-alumina powder comprises NiO.
11. The method for producing the beta-alumina-based sintered compact according to claim 10 , wherein a chemical composition of the beta-alumina-based sintered compact, based on oxides, is
from 8 to 15 mass % of Na 2 O;
from 5 to 30 mass % of Nb 2 O 5 ;
from 1 to 10 mass % of NiO; and
a remainder of Al 2 O 3 .
12. A beta-alumina-based sintered compact, comprising:
as chemical components, based on oxides, Na 2 O and Al 2 O 3 ; and
as a crystalline phase, a beta alumina crystalline phase and an RNbO 3 crystalline phase;
wherein R is at least one element selected from the group consisting of Li, Na, and K.
13. The beta-alumina-based sintered compact according to claim 12 , wherein the beta-alumina crystalline phase comprises a β″ alumina crystalline phase.
14. The beta-alumina-based sintered compact according to claim 12 , wherein R is Na.
15. The beta-alumina-based sintered compact according to claim 12 , comprising NiO.
16. The beta-alumina-based sintered compact according to claim 15 , wherein a chemical composition of the beta-alumina-based sintered compact, based on oxides, is:
from 8 to 15 mass % of Na 2 O,
from 5 to 30 mass % of Nb 2 O 5 ;
from 1 to 10 mass % of NiO; and
a remainder of Al 2 O 3 .