JPH08178443A - Regenerator - Google Patents

Abstract

PURPOSE: To increase the specific heat in a specific range and to improve cold heat accumulation efficiency by forming a magnetic material made of a cold heat accumulating material of one or more of rare earth elements of a specific range of Ce, Gd, Tb, Dy, Ha, Er, Tm, Pr and Nd and an additive of a specific range containing Si. CONSTITUTION: A cold heat accumulating material is formed of a magnetic material made of one or more of 35 to 95at.% of rare earth elements of Ce, Gd, Tb, Dy, Ho, Er, Tm, Pr and Nd and 5 to 65at.% of additive containing Si. The accumulating material made of the magnetic material generates a composition in which R, RSi compound, RSi2 compound and R5 S4 compound are mixed. The magnetic transition point of the compound at substantially 8 to 30K is most and the peak of the specific heat exists near the point, and hence the specific heat can be improved at substantially 8 to 30K.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regenerator filled with a regenerator material having a high specific heat at a low temperature and is used in various refrigerators.

[0002]

2. Description of the Related Art Refrigerators that use various types of regenerators such as Stirling type, GM (Gihoed McMahon) type, pulse tube type, etc. must have a regenerator filled with a regenerator material in order to improve refrigerating capacity. Become. This regenerator takes heat from the compressed working gas flowing in one direction and stores the heat.
It transfers the heat stored in the expanded working gas flowing in the opposite direction.

Conventionally, alloys such as copper and lead are often used as the regenerator material filled in the regenerator. However, since the regenerator material made of copper or lead has only the specific heat of the lattice system, the specific heat is large at 40 K or more, but becomes excessively small at an extremely low temperature of 20 K or less. Therefore, when the regenerator filled with the regenerator material is used in a refrigerator (particularly, a multistage refrigerator), heat cannot be sufficiently absorbed from the compressed working gas, and the expansion does not occur. The heat cannot be sufficiently transferred to the working gas. As a result, a refrigerator using a regenerator filled with such a regenerator material has a problem that it cannot reach an extremely low temperature.

Therefore, as a regenerator proposed in order to solve such a problem, Japanese Patent Laid-Open No. 1-310269 has been proposed.
The one shown in Japanese Patent Publication is known. As a typical example thereof, Er having not only the specific heat of the lattice system but also the specific heat of the spin system
A regenerator filled with a magnetic regenerator material made of ₃ Ni is disclosed. This is because at a cryogenic temperature of 20 K or less, the specific heat thereof is larger than that of the regenerator material made of copper or lead, so that the regenerator efficiency can be improved at an extremely low temperature of 20 K or less (particularly less than 10 K) than the regenerator material made of copper or lead.

[0005]

However, the above-mentioned E
In the regenerator material made of r ₃ Ni, the magnetic transformation point (that is, the phase transition between magnetic states) exists near 8K, so that the specific heat is large at less than 8K, but becomes small at 8 to 30K. Therefore, although the cold storage efficiency is high at an extremely low temperature of less than 8K, the cold storage efficiency is insufficient at 8 to 30K. Therefore, in the above-mentioned cool storage material composed of Er ₃ Ni, 10 to ₃
There is a problem that it is difficult to apply to a refrigerator that generates 0K of refrigeration.

[0006] Therefore, it is a technical object of the present invention to provide a regenerator having a regenerator material having a large specific heat at 8 to 30K and capable of improving the regenerator efficiency at 8 to 30K.

[0007]

In order to solve the above technical problems, the technical means taken in the present invention is a regenerator filled with a regenerator material, wherein the regenerator material is at least Ce, Gd, Tb, Dy, Ho, Er, Tm, Pr, N
rare earth element 35-95 at which is one or more of d
%, And an additive containing at least Si 5 to 65 at%
That is, the magnetic substance is composed of.

Here, Ce, Gd, Tb, Dy, Ho,
Additive 5 containing 35 to 95 at% of rare earth element containing one or more of Er, Tm, Pr and Nd and Si
In the regenerator material using the magnetic substance composed of ˜65 at%, as is clear from FIGS. 1 and 2, R, RSi compound, R
A structure in which Si ₂ compound, R ₅ Si ₄ compound, etc. are mixed is generated. And the magnetic transformation point of these compounds is about 8 to
Since many of them have a temperature of 30 K and a peak of the specific heat exists near the magnetic transformation point, the specific heat can be improved at about 8 to 30 K.

When the content of the rare earth element is less than 35 at% (that is, the content of the additive is more than 65 at%), as is clear from the example of the phase diagram of Er-Si shown in FIG.
Its magnetic transformation point becomes substantially 8~30K Er ₅ Si _3, E
A structure in which r ₅ Si ₄ , ErSi, Er ₃ Si ₅ , ErSi _{2 and the} like are mixed is not generated at all (here, Er ₅ S
The magnetic transformation points of i ₃ , Er ₃ Si ₅ and ErSi ₂ are not clarified in FIG. 1, but these magnetic transformation points are also within the range of approximately 0 to 30K. ). Furthermore, since the phase of Si simple substance having only the specific heat of the lattice system is generated, the specific heat at 8 to 30K cannot be improved.
On the other hand, it was experimentally confirmed that when the content of the rare earth element exceeds 95 at% (that is, the content of the additive is less than 5%), the specific heat decreases around 10K.

Further, from FIG. 2, the content of the rare earth element R is 35.
When the content of the additive is ˜40 at% (the content of the additive is 60-65 at%), a structure in which the ErSi ₂ compound and the Er ₃ Si ₅ compound are mixed can be generated, and the content of the rare earth element R is 40 to 50 at%. (The content of the additive is 50 to 6
0 at%), Er ₃ Si ₅ compound and ErSi
It is possible to generate a structure mixed with a compound, and when the content of the rare earth element R is 50 to 55 at% (the content of the additive is 45 to 50 at%), the ErSi compound and the E
It is possible to generate a structure in which an r ₅ Si ₄ compound is mixed, and the content of the rare earth element is 55 at% to 63 at%.
When the content of the additive is 37 to 45 at%, E
It is possible to generate a texture in which an r ₅ Si ₄ compound and an Er ₅ Si ₃ compound are mixed, and the rare earth element is 63 at% or more.
When the content is 95 at% (the content of the additive is ₅ to 37 at%), a mixed structure of Er ₅ Si ₃ compound and Er can be generated, so that the peak of specific heat is adjusted according to the ratio of the mixed structure. It will be possible.

In the above technical means, in order to improve the specific heat of 5 to 8K, B, Al and I are added in the additive.
n, Ag, Ge, Ga, Sn, Au, Mg, Zn, P
d, Pt, Re, Cs, Ir, Fe, Mn, Cr, C
It is desirable to contain at least one element selected from d, Hg and Os. Since the magnetic transformation point of the compound formed by these elements is 30 K or less, the specific heat of 5 to 8 K can be further improved.

Here, in order not to lower the specific heat at 8 to 30 K, the content of these elements is 5 at%.
The following is desirable. If it exceeds 5 at%, the specific heat at 8 to 30 K may decrease.

[0013]

According to the above technical means, the regenerator material is at least Ce, Gd, Tb, Dy, Ho, Er, Tm, Pr,
One or more Nd rare earth elements 35-95a
5% to 65 at% of an additive containing t% and at least Si
%, The structure in which R ₅ Si ₄ , RSi, RSi _{2 and the} like having a magnetic transformation point of about 8 to 30 K are mainly mixed is generated, so that the conventional magnetic transformation point of Er ₃ Ni is The specific heat at 8 to 30K can be improved as compared with the cold storage material at about 8K.

From the above, the heat storage efficiency at 8 to 30K can be improved, and the regenerator by the above technical means can be used at 8 to 30K.
It can be applied to refrigerators that generate 30K of refrigeration.

[0015]

【Example】

[Example 1] 8.56 g (50 at%) of Er block and 1.44 g (50 at%) of Si block were placed in an arc melting furnace, and the inside of the arc melting furnace was vacuum-suctioned and then replaced with argon gas. Then, arc melting is performed to manufacture a regenerator material, which is cut into 5 × 5 × 7 mm. Here, from the state diagram shown in FIG. 2, the regenerator materials manufactured as described above are Er and S
If i is exactly 50 at%, ErSi (magnetic transformation point 1
Only 0K, specific heat peak 12K) is produced, but due to a slight composition error, Er ₅ Si ₄ or Er ₃ S
The structure has a mixture of i ₅ and ErSi.

Next, the specific heat of the regenerator material manufactured as described above was measured at about 3 to 30 K by the adiabatic method using a Ge thermometer. Here, the adiabatic method is to measure the temperature change ΔT when Joule heat ΔQ is applied to a sample (here, ingot) under adiabatic conditions, and divide the Joule heat ΔQ by the temperature change ΔT to obtain the specific heat ΔC. Is the way to do it. The specific heat measurement result is shown in FIG.

As is apparent from FIG. 3, in the cold storage material of Example 1, the cold storage material using Er ₃ Ni (conventional example 1) and P were used.
Compared with the cold storage material using b (conventional example 2), approximately 8 to 12
It can be seen that the specific heat at K becomes large, and the specific heat at 12 to 30 K is almost the same as the conventional example. Most of the regenerator materials of Example 1 were ErSi compounds (magnetic transformation point 1
0K), the peak of specific heat is about 8K-12K
It is thought to be because it exists in.

[Embodiment 2] Ho block 8.54 g (5
0 at%) and Si block 1.46 g (50 at%) were placed in an arc melting furnace, and the same as Example 1. In this case, the regenerator material of Example 2 had HoSi (magnetic transformation point 25
K, specific heat peak 21K) is produced, but due to slight composition error, Ho ₅ Si ₄ or Ho ₃ Si
_The organization will be a mixture of ₅ and HoSi.

The specific heat of the regenerator material of Example 2 was measured in the same manner as in Example 1, and the measurement results are shown in FIG.

As is apparent from FIG. 3, even in the regenerator material of Example 2, the regenerator material using Er ₃ Ni (conventional example 1) and P were used.
Compared with the regenerator material using b (conventional example 2), approximately 10 to 3
The specific heat at 0K is large. Most of the regenerator materials of Example 2 were HoSi compounds (magnetic transformation point 25
Since it is K), it is considered that the specific heat peak exists near 23K.

[Conventional Example 1] Er block 8.95 g (7
5 at%) and Ni block 1.05 g (25 at%) were placed in the arc melting furnace, and the same as Example 1. Here, the regenerator material of Conventional Example 1 was Er ₃ Ni (magnetic transformation point 8K), and its specific heat was measured in the same manner as in Example 1, and the measurement result is shown in FIG.

As is apparent from FIG. 4, the regenerator material of Conventional Example 1 has a large specific heat at 8 K or less, but the specific heat at 8 K or more is smaller than that of Examples 1 and 2. this is,
It is considered that this is because the magnetic transformation point of Er ₃ Ni exists at 8K and the peak of specific heat exists near 7K.

[Conventional Example 2] A regenerator material was manufactured by melting 10 g of Pb. The specific heat of this regenerator material was measured in the same manner as in Example 1, and the measurement results are shown in FIG.

As is apparent from FIG. 3, the specific heat at 25 K or less is smaller in the regenerator material of Conventional Example 2 than in Examples 1 and 2. It is considered that this is because the specific heat of the lattice system due to the lattice vibration is remarkably lowered with the temperature drop and does not have the specific heat of the spin system.

The regenerator filled with the regenerator material according to Examples 1 and 2 is of a Stirling type, a GM type, a pulse tube type, a Solvay type, a resonance tube type or the like which produces a refrigeration of 30 K or less, particularly 8 to 30 K. It can be applied to various refrigerators. It is also possible to use each stage according to the temperature of the multistage refrigerator.

[0026]

The present invention has the following effects.

According to the present invention, the regenerator material is at least C
e, Gd, Tb, Dy, Ho, Er, Tm, Pr, Nd
35% to 95 at% of rare earth elements that are one or more of
And at least 5 to 65 at% of an additive containing Si, the specific heat at 8 to 30 K can be improved. As a result, the cold storage efficiency at 8 to 30K can be improved, and the present invention can be applied to a refrigerator that generates refrigeration at 8 to 30K.

[Brief description of drawings]

FIG. 1 is a graph showing a magnetic transformation point of an alloy existing in a regenerator material according to the present invention.

FIG. 2 is a phase diagram of Er—Si.

FIG. 3 is a graph showing specific heat characteristics at low temperatures of Examples 1 and 2 of the present invention and Conventional Examples 1 and 2.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshiki Hoshino 473 Takagi, Fuso-cho, Niwa-gun, Aichi (72) Inventor Uichiro Mizutani 2-12-6 Sotoyama, Minami-ku, Nagoya-shi, Aichi

Claims (3)

[Claims] 1. A regenerator filled with a regenerator material, wherein the regenerator material is at least Ce, Gd, Tb, Dy, H.
A cold storage characterized by being a magnetic material comprising 35 to 95 at% of a rare earth element which is one or more of o, Er, Tm, Pr and Nd, and 5 to 65 at% of an additive containing at least Si. vessel. 2. The regenerator according to claim 1, wherein the additive is B, Al, In, Ag, Ge, Ga, S.
n, Au, Mg, Zn, Pd, Pt, Re, Cs, I
A regenerator characterized by containing at least one element selected from r, Fe, Mn, Cr, Cd, Hg, and Os. 3. The regenerator according to claim 2, wherein the content of the at least one element is 5 at% or less.