Magnetic material for magnetic refrigeration
A magnetic material for magnetic refrigeration has a composition represented by (R1 1-y R2 y ) x Fe 100-x (R1 is at least one of element selected from Sm and Er, R2 is at least one of element selected from Ce, Pr, Nd, Tb and Dy, and x and y are numerical values satisfying 4≦x≦20 atomic % and 0.05≦y≦0.95), and includes a Th 2 Zn 17 crystal phase, a Th 2 Ni 17 crystal phase, or a TbCu 7 crystal phase as a main phase.
1. A magnetic material consisting of a composition represented by the formula:
(R1 1-y R2 y ) x (Fe) 100-x
wherein:
R1 is at least one element selected from Sm and Er,
R2 is at least one element selected from Ce, Pr, Nd, Tb and Dy,
x is a value satisfying 4≦x≦20 atomic %, and
y is a value satisfying 0.05≦y≦0.95,
wherein optionally a part of Fe is substituted by at least one element selected from Mn and Ni and
wherein optionally a part of R2 is substituted by at least one element selected from La, Gd, Ho, Y, Tm and Yb, and
wherein the crystal phase of the magnetic material consists essentially of a crystal phase with a structure analogous to at least one selected from a Th 2 Zn 17 crystal structure, a Th 2 Ni 17 crystal structure and a TbCu 7 crystal structure and has a Curie temperature of 320K or less.
2. The material according to claim 1 , wherein the magnetic material exhibits a second order magnetic phase transition.
3. The material according to claim 1 , wherein element R2 contains 70 atomic % or more of at least one selected from Ce, Pr and Nd.
4. The material according to claim 1 , wherein element R2 is at least one selected from Ce, Pr and Nd.
5. The material according to claim 1 , wherein a part of R2 is substituted by at least one element selected from La, Gd, Ho, Y, Tm and Yb.
6. The material according to claim 5 , wherein up to 20 at. % of R2 is substituted by at least one element selected from La, Gd, Ho, Y, Tm and Yb.
7. The material according to claim 1 , wherein a part of Fe is substituted by Mn.
8. The material according to claim 1 , wherein the crystal phase of the magnetic material consists essentially of a Th 2 Zn 17 crystal structure.
9. The material according to claim 1 , wherein the crystal phase of the magnetic material consists essentially of a Th 2 Zn 17 crystal structure.
10. The material according to claim 1 , wherein the crystal phase of the magnetic material consists essentially of a TbCu 7 crystal structure.
11. The material according to claim 1 , wherein R1 consists of Sm and Er.
12. The material according to claim 1 , wherein the magnetic material has a Curie temperature of 250 K-320 K.
13. The material according to claim 1 , wherein the magnetic material has a Curie temperature of 270 K-320 K.
14. The material according to claim 1 , wherein a part of Fe is substituted by Ni.
15. The material according to claim 14 , wherein up to 20 at. % of Fe is substituted by Ni.
16. The material according to claim 1 , wherein said part of Fe is not substituted by Mn or Ni.
17. The material according to claim 1 , wherein said part of R2 is not substituted by at least one element selected from La, Gd, Ho, Y, Tm and Yb.
18. The material according to claim 1 , wherein said part of Fe is not substituted by Mn or Ni and wherein said part of R2 is not substituted by at least one element selected from La, Gd, Ho, Y, Tm and Yb.