Magnetic material

• US 20030051774A1
• Filed: 03/18/2002
• Published: 03/20/2003
• Est. Priority Date: 03/27/2001
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Sahashi, Masashi, Saito, Akiko, Sawa, Takao, Kobayashi, Tadahiko
• Granted Patent: US 6,676,772 B2
• Time in Patent Office: Days
• US Class Current: 148/302
• CPC Class Codes: F25B 21/00 Machines, plants or systems, using electric or magnetic effects
• CPC Class Codes: H01F 1/015 Metals or alloys
• CPC Class Codes: Y02B 30/00 Energy efficient heating, ventilation or air conditioning [HVAC]

Abstract

The magnetic material for magnetic refrigeration of the present invention is characterized by exhibiting, in a certain temperature region, preferably, only in part of a temperature region from 200 K to 350 K, an inflection point at which a second order differential coefficient of a magnetization curve changes from positive to negative with respect to a magnetic field, within the range of this magnetic field formed using a permanent magnet unit. This magnetic material of the present invention can generate a low temperature by using a relatively low magnetic field, by transferring the entropy between the electron spin system and the lattice system near the temperature at which an inflection point appears on the magnetization curve. Examples of the magnetic material meeting this condition are La(Fe,Si)₁₃, (Hf,Ta)Fe₂, (Ti,Sc)Fe₂, and (Nb,Mo)Fe₂, each containing 50 to 60 atomic % of transition metals such as Fe.

Claims

1. A magnetic material for magnetic refrigeration, which exhibits, in a certain temperature region, an inflection point at which a second order differential coefficient of a magnetization curve changes from positive to negative with respect to a magnetic field, within the range of the strength of the magnetic field formed using a permanent magnet.

2. A material according to claim 1, which exhibits, only in part of a temperature region from 200 K to 350 K, an inflection point at which a second order differential coefficient of a magnetization curve changes from positive to negative with respect to a magnetic field, within the range of the strength of the magnetic field of not more than 1 tesla.

3. A material according to claim 1, which comprises:

a total of 50 to 96 atomic % of one or not less than two elements selected from the group consisting of Fe, Co, Ni, Mn, and Cr;

a total of 4 to 43 atomic % of one or not less than two elements selected from the group consisting of Si, C, Ge, Al, B, Ga, and In; and

a total of 4 to 20 atomic % of one or not less than two elements selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb.

4. A material according to claim 3, wherein said magnetic material further comprises 4 to 25 atomic % of Si.

5. A material according to claim 1, which comprises:

a total of 60 to 96 atomic % of one or not less than two elements selected from the group consisting of Fe, Co, Ni, Mn, and Cr; and

a total of 4 to 40 atomic % of one or not less than two elements selected from the group consisting of Sc, Ti, Y, Zr, Nb, Mo, Hf, Ta, and W.

6. A material according to claim 5, wherein said magnetic material further comprises a total of not less than 25 atomic % of one or not less than two elements selected from the group consisting of Ti, Zr, Nb, and Hf.

7. A material according to claim 1, which comprises:

a total of 50 to 80 atomic % of one or not less than two elements selected from the group consisting of Fe, Co, Ni, Mn, and Cr;

a total of 20 to 50 atomic % of one or not less than two elements selected from the group consisting of Sb, Bi, P, and As.

8. A material according to any one of claims 3 to 7, wherein the content of oxygen is not more than 1 atomic %.