Material for magnetic refrigeration preparation and application

• US 20040250550A1
• Filed: 01/30/2004
• Published: 12/16/2004
• Est. Priority Date: 07/31/2001
• Status: Active Grant

• Current Assignee: Stichting Voor de Technische Wetenschappen, Universiteit Van Amsterdam Faculteit Der Natuuwetenschappen Wiskunde EN Informatica Amsterdam
• Original Assignee: Stichting Voor de Technische Wetenschappen, Universiteit Van Amsterdam Faculteit Der Natuuwetenschappen Wiskunde EN Informatica Amsterdam
• Inventors: Bruck, Ekkehard Hubertus, Tegusi, Ojiyed, De Boer, Frank Roelof
• Granted Patent: US 7,069,729 B2
• Time in Patent Office: Days
• US Class Current: 62/3.1
• CPC Class Codes: F25B 21/00 Machines, plants or systems, using electric or magnetic effects
• CPC Class Codes: H01F 1/017 Compounds
• CPC Class Codes: Y02B 30/00 Energy efficient heating, ventilation or air conditioning [HVAC]

Abstract

A material that can be used for magnetic refrigeration, wherein the material substantially has the general formula (A_YB_1−y)_2+δC_1−xD_x) wherein A is selected from Mn and Co; B is selected from Fe and Cr; C and D are different and are selected from P, As, B, Se, Ge, Si and Sb; x and y each is a number in the range 0-1; and δ is a number from (−0.1)-(+0.1).

Claims

1. A material that can be used for magnetic refrigeration, wherein the material substantially has the general formula

(A_YB₁₋

y)_2+δ

C<sub>1−

x</sub>D_x)

wherein

A is selected from Mn and Co;

B is selected from Fe and Cr;

C and D are different and are selected from P, As, B, Se, Ge, Si and Sb;

x and y each is a number in the range 0-1; and

δ

is a number from (−

0.1)-(+0.1).

2. A material according to claim 1, wherein at least 90% of A is Mn;

at least 90% of B is Fe;

at least 90% of C is P; and

at least 90% of D is As or Sb.

3. A material according to claim 2, wherein the material has the general formula MnFe(P₁₋

xAs_x).

4. A material according to claim 2, wherein the material has the general formula MnFe(P₁₋

xSb_x).

5. A material according to claim 1, wherein x is a number in the range from 0.3-0.6.

6. A material according to claim 1, wherein the material substantially has the general formula MnFeP_0.45As_0.55.

7. A material according to claim 1, wherein if D is As, As is partly replaced with Si and/or Ge.

8. A material according to claim 7, wherein 1-40% of the As is replaced with Si and/or Ge.

9. A method for the manufacture of the material according to claim 3, wherein powders of iron arsenide (FeAs₂) or iron antimony (FeSb₂);

manganese phosphide (Mn₃P₂);

iron (Fe); and

Manganese (Mn) are mixed in suitable quantities to produce a powder mixture that complies with the general formula MnFe(P<sub>1−

x</sub>As_x) or MnFe(P<sub>1−

x</sub>Sb_x) and the powder mixture is subsequently molten under an inert atmosphere and annealed.

10. A method for the manufacture of the material according to claim 1, wherein the same comprises mixing powders of the compounds Fe₂P, MnAs₂, Mn and P in suitable weight proportions, grinding the powders to produce a powder mixture complying with the general formula MnFe(P₁₋

xD_x), melting the powder mixture in an inert atmosphere, and annealing the resulting alloy.

11. A method according to claim 10, wherein the powder mixture is sintered at a temperature of approximately 1000°

C. and the resulting alloy is heated at a temperature of approximately 650°

C.

12. A method according to claim 10, wherein the sintering step takes at least approximately one hour and the annealing step takes at least approximately 24 hours.

13. A method according to claim 10, wherein the starting materials are mixed in quantities so as to provide a composition having the formula MnFeP_0.45As_0.55.

14. A method according to claim 10, wherein prior to melting the powder mixture is compressed to a pill.

15. A method according to claim 10, wherein the inert atmosphere is an argon atmosphere.

16. A method according to claim 10, wherein the molten powder mixture is annealed at a temperature in the 750-950°

C. range.

17. A method of using the material according to claim 1 comprising employing the material in magnetic refrigeration in the 250-3200 K range.

18. A material according to claim 2, wherein at least 95% of A is Mn.

19. A material according to claim 2, wherein at least 95% of B is Fe.

20. A material according to claim 2, wherein at 95% of C is P.

21. A material according to claim 1, wherein at least 95% of D is As or Sb.

22. A material according to claim 8, wherein 10-30% of the As is replaced with Si and/or Ge.

23. A material according to claim 22, wherein 17-23% of the As is replaced with Si and/or Ge.

24. A material according to claim 23, wherein approximately 20% of the As is replaced with Si and/or Ge.

25. A method according to claim 10, wherein D comprises As and Si and/or Ge.

26. A method according to claim 13, wherein the starting materials are mixed in quantities so as to provide a composition having the formula MnFeP_0.45As_9.45(Si/Ge)_0.10.