Cryogenic regenerator material, regenerative cryocooler, and system including regenerative cryocooler
According to an embodiment, a cryogenic regenerator material contains a silver oxide. A molar ratio of silver atoms to oxygen atoms contained in the cryogenic regenerator material: Ag/O is 1.0 or more and 4.0 or less. The cryogenic regenerator material contains at least one selected from AgO, Ag 2 O and Ag 3 O as the silver oxide.
1. A regenerative cryocooler, comprising a cryogenic regenerator material comprising a silver oxide, the molar ratio of silver atoms to oxygen atoms contained in the cryogenic regenerator material: Ag/O being 1.0 or more and 4.0 or less.
2. The regenerative cryocooler of claim 1 , wherein the molar ratio of silver atoms to oxygen atoms contained in the cryogenic regenerator material: Ag/O is 1.8 or more and 3.2 or less.
3. The regenerative cryocooler of claim 1 , wherein the silver oxide is contained in a ratio of 50% by volume or more based on a whole volume of the cryogenic regenerator material.
4. The regenerative cryocooler of claim 1 , wherein the silver oxide is at least one selected from the group consisting of AgO, Ag 2 O and Ag 3 O.
5. The regenerative cryocooler of claim 1 , wherein the silver oxide comprises a first phase of silver oxide and a second phase of silver oxide having different crystal structures.
6. The regenerative cryocooler of claim 5 , wherein, assuming that A is a half width of a main peak of the first phase of silver oxide and B is a half width of a main peak of the second phase of silver oxide in a powder X-ray diffraction spectrum, the following condition is satisfied: A/B ≥1.2.
7. The regenerative cryocooler of claim 5 , wherein a crystal structure of the first phase of silver oxide is cubic, and a crystal structure of the second phase of silver oxide is hexagonal.
8. The regenerative cryocooler of claim 5 , wherein the first phase of silver oxide is Ag 2 O, and the second phase of silver oxide is Ag 3 O.
9. The regenerative cryocooler of claim 5 , wherein the first phase of silver oxide is present at the grain boundaries of the second phase of silver oxide.
10. The regenerative cryocooler of claim 1 , further comprising an Ag coating layer on a surface of the cryogenic regenerator material.
11. The regenerative cryocooler of claim 1 , further comprising at least one regenerator material selected from a copper alloy mesh and a stainless steel mesh.
12. A system comprising the regenerative cryocooler of claim 1 .
13. The regenerative cryocooler of claim 4 , wherein the silver oxide is AgO.
14. The regenerative cryocooler of claim 4 , wherein the silver oxide is Ag 2 O.
15. The regenerative cryocooler of claim 4 , wherein the silver oxide is Ag 3 O.
16. The system of claim 12 , wherein said system is a superconducting electromagnet apparatus.
17. The system of claim 12 , wherein said system is a magnetic resonance imaging (MRI) apparatus.
18. The system of claim 12 , wherein said system is a cryopump apparatus.
19. The system of claim 12 , wherein said system is a Josephson voltage standard system.
20. The system of claim 12 , wherein said system is a single-crystal pulling apparatus.