JP4482695B2 - Low-temperature magnetic refrigeration work material and magnetic refrigeration system - Google Patents

Description

  The present invention relates to a magnetic refrigeration working material that can also be used for cooling at a temperature of 190 K or less, and a magnetic refrigeration system thereof.

  Magnetic refrigeration is attracting attention as a new refrigeration system that replaces the conventional gas refrigeration that uses chlorofluorocarbon-based gases that cause environmental destruction such as destruction of the ozone layer and global warming. In magnetic refrigeration, a magnetic substance is used as a refrigerant (refrigeration working substance), and its magnetocaloric effect, that is, the magnetic entropy change that occurs when the magnetic order of the magnetic substance is changed by a magnetic field in an isothermal state, and the magnetic order of the magnetic substance in an adiabatic state. The adiabatic temperature change that occurs when is changed by a magnetic field is used. Therefore, refrigeration can be performed without using any chlorofluorocarbon or alternative chlorofluorocarbon gas. In addition, the refrigeration efficiency of magnetic refrigeration is higher than that of gas refrigeration. That is, magnetic refrigeration is an environmentally friendly refrigeration system that leads to energy saving. To realize magnetic refrigeration, it is desired to develop a highly efficient refrigeration material that exhibits a large magnetocaloric effect at a low magnetic field.

In such a situation, NaZn ₁₃ type La (Fe _x Si _1-x ) ₁₃ and its hydrogen absorbing compound are about 190-340.
It is raised as a candidate for a frozen working substance in the K temperature range. La (Fe _x Si _1-x ) ₁₃ compound has a Curie temperature of about 190
A giant magnetocaloric effect is shown just above K, along with the itinerant electron metamagnetic transition, which is a first-order phase transition from paramagnetism to ferromagnetism by applying a magnetic field. This Curie temperature is variable depending on the Fe concentration. In addition, about 180% of this compound.
Curie temperature of K can be controlled arbitrarily in the temperature range up to about 340 K due to hydrogen absorption, and due to metamagnetic transition at any temperature of 190-340 K by controlling the amount of absorbed hydrogen A large magnetocaloric effect is obtained. The synergistic magnetocaloric effect of La (Fe _x Si _1-x ) ₁₃ and its hydrogen absorbing compound can be achieved by improving the magnetocaloric effect of Fe concentration.

Magnetic refrigeration is expected to be applied not only to home appliances such as refrigerators and freezers near room temperature, but also to refrigeration technology that supports gas liquefaction industries and superconducting devices. However, NaZn ₁₃ type La (Fe _x Si _1-x ) ₁₃ is about 190
Since it shows a giant magnetocaloric effect just above the Curie temperature of K, it cannot be applied to refrigeration technology below 190 K.
JP 2000-95862 A JP-A-6-69190

As mentioned above, NaZn ₁₃ type La (Fe _x Si _1-x ) ₁₃ is about 190
Giant magnetocaloric effect just above the Curie temperature of K. The present invention makes it possible to control the decrease in Curie temperature of La (Fe _x Si _1-x ) ₁₃ and
The object is to provide a high-performance magnetic refrigeration working material that exhibits a giant magnetocaloric effect in the temperature range below K.

According to the present invention, in the NaZn ₁₃ type _{La (Fe x Si 1-x} ) 13 which is a magnetic refrigeration working substance, Ce or / and Mn is partially substituted with, La _1-z of the composition Ce _z (Fe _x Mn A magnetic refrigeration working material characterized in that _y Si _1-xy ) ₁₃ is obtained.

    The magnetic refrigeration is characterized in that the x value is 0.86 to 0.88, the y value is 0.0 to 0.025, and the z value is 0.0 to 0.030. A working substance is obtained.

Furthermore, the magnetic refrigerant material NaZn ₁₃ type _{La 1-z Ce z (Fe} x Mn y Si 1-xy) 13 to one or magnetic refrigeration system in which a plurality of used cooling control what changed its composition can get.

The magnetic refrigeration, characterized in that said using a magnetic refrigerant material NaZn ₁₃ type _{La 1-z Ce z (Fe} x Mn y Si 1-xy) 13, to cool control range around 200K from near the temperature 70K A scheme is obtained.

Further, by using the magnetic refrigeration working substance NaZn ₁₃ type _{La 1-z Ce z (Fe} x Mn y Si 1-xy) 13, a magnetic refrigeration system for cooling control range around 200K from near the temperature 70K, NaZn ₁₃ magnetic refrigeration system is obtained which is characterized by being configured the composition of the type _{La 1-z Ce z (Fe} x Mn y Si 1-xy) 13 as three.

Also, the three types of configuration, the _{La 0.65 Ce 0.35 (Fe 0.860 Mn} 0.025 Si 0.115) 13 as a cooling near 90K, the _{La 0.65 Ce 0.35 (Fe 0.860 Mn} 0.025 Si 0.115) 13 as a cooling near 130K, 200K A magnetic refrigeration system characterized by being configured as La (Fe _0.88 Si _0.12 ) ₁₃ for cooling in the vicinity can be obtained.

In the magnetic refrigeration system for cooling control using multiple ones of the magnetic refrigeration working substance NaZn ₁₃ type _{La 1-z Ce z (Fe} x Mn y Si 1-xy) 13 for changing one or its composition, magnetic refrigeration system, characterized in that for applying a magnetic field actuating the magnetic refrigerant material NaZn ₁₃ type _{La 1-z Ce z (Fe} x Mn y Si 1-xy) 13 is obtained.

    The magnetic refrigeration system is characterized in that the strength of the magnetic field is between 1T and 2T.

According to the present invention, at any temperature _{La 1-z Ce z (Fe} x Mn y Si 1-xy) 13 of Ce and Mn substitution amount control to be at 80 ~ 190 K, excellent in a relatively low magnetic field The magnetocaloric characteristics can be obtained.

It shows the thermomagnetic curve of the _{La (Fe 0.89-y Mn y} Si 0.11) 13 in FIG. 1. As the Mn concentration increases, the Curie temperature decreases greatly. Further, the hysteresis decreases with increasing Mn concentration, and the embodiment of the present invention will be described below with reference to the drawings at the Curie temperature.
The temperature-induced first order phase transition of becomes gradually unclear. From the Maxwell relation, the magnetic entropy change is expressed by the following equation.

Here, M is magnetization, B is an applied magnetic field, and T is temperature. That is, the magnitude of the temperature change of magnetization in a constant magnetic field is reflected in the magnetic entropy change. As the Mn concentration increases, the temperature change of magnetization at the Curie temperature is reduced, so a decrease in magnetic entropy change is predicted. 2, the Si concentration is constant, shows the magnetic entropy change of La with different Fe concentrations _{(Fe 0.89-y Mn y Si} 0.11) 13. Since the Curie temperature decreases as the Mn concentration increases, the magnetic entropy change shifts to the low temperature side due to Mn partial substitution. However, since the temperature change of magnetization at the Curie temperature becomes smaller as the Curie temperature decreases, the magnetic entropy change gradually becomes smaller.

Next, FIG. 3 shows a thermomagnetic curve of La (Fe _0.88 Mn _y Si _0.12-y ) _{13 with} the Fe concentration kept constant and the Si concentration changed. Curie temperature falls by Mn partial substitution. Even if the Curie temperature is lowered, the change in magnetization at the Curie temperature is as large as that before partial replacement. FIG. 4 shows the temperature dependence of the magnetic entropy change of La (Fe _0.88 Mn _y Si _0.12-y ) ₁₃ .

As the Curie temperature decreases due to partial substitution, the peak of the magnetic entropy change shifts to the low temperature side. At this time, the magnitude of the magnetic entropy change hardly changes. As a result, this compound is -21 at around 170K.
The magnetic entropy change of J / kg K is shown. The results of FIGS. 1, 2, 3 and 4 indicate that a high Fe concentration is essential to obtain a large magnetic entropy change even after Mn substitution. However, since La-Mn is non-solid, for example, when the Fe composition is about 0.88, the solidity limit of Mn is as small as about 0.015, and the Curie temperature is controlled to decrease only in the temperature range of about 160 to 180K. I can't.

Next, a thermomagnetic curve of _{La 1-z Ce z (Fe} 0.88 Si 0.12) 13 was changed only La concentration in FIG. Due to partial substitution of Ce, the Curie temperature decreases, and the change in magnetization at the Curie temperature becomes significant. Therefore, as shown in FIG. 6, the magnetic entropy change also increases as the Curie temperature decreases. However, the solid limit of Ce is as small as about 0.2, and the Curie temperature cannot be controlled to greatly decrease.

Therefore, partial substitution of both Mn and Ce of La (Fe _0.88 Si _0.12 ) ₁₃ was performed. FIG. 7 shows the temperature dependence of the magnetic entropy change of La (Fe _0.88 Si _0.12 ) ₁₃ , La _0.8 Ce _0.2 (Fe _0.880 Mn _0.015 Si _0.105 ) ₁₃ and La _0.65 Ce _0.35 (Fe _0.860 Mn _0.025 Si _0.115 ) ₁₃ . In La _0.8 Ce _0.2 (Fe _0.880 Mn _0.015 Si _0.105 ) ₁₃ in which the Fe concentration was 0.88 and Mn and Ce were substituted to almost the solid limit, the Curie temperature decreased to about 130 K, and the magnetic entropy change was larger than before substitution. Observed. Furthermore, in La _0.65 Ce _0.35 (Fe _0.860 Mn _0.025 Si _0.115 ) ₁₃ in which the Fe concentration is 0.86 and Mn and Ce are substituted to almost the solid limit, the magnetic entropy change is small, but the solid limit of Ce and Mn is The operating temperature dropped to around 80K to expand. In other words, large magnetic entropy change can be obtained at any temperature _{La 1-z Ce z (Fe} x Mn y Si 1-xy) 13 of Ce and Mn 70K~190 K by controlling the amount of substitution.

Next, RCP was examined. RCP is defined as the product of the maximum value of the peak of magnetic entropy change and the half value width of the peak, and corresponds to the maximum value of the amount of heat that can be absorbed and released by the magnetic material in one magnetic refrigeration cycle. This is a magnetocaloric characteristic that is particularly important when cooling a wide temperature range. Table 1 shows _RCPs of La (Fe _0.88 Si _0.12 ) ₁₃ , La _0.8 Ce _0.2 (Fe _0.880 Mn _0.015 Si _0.105 ) ₁₃ and La _0.65 Ce _0.35 (Fe _0.860 Mn _0.025 Si _0.115 ) ₁₃ . Here, Tc is the Curie temperature. The RCPs in all compositions have similar large values. Therefore, it is possible to obtain a large RCP at any temperature _{La 1-z Ce z (Fe} x Mn y Si 1-xy) 13 of Ce and Mn 80 to 190 K by controlling the amount of substitution.

Figure 8 shows the temperature dependence of the adiabatic temperature change of La (Fe _0.88 Si _0.12 ) ₁₃ , La _0.8 Ce _0.2 (Fe _0.880 Mn _0.015 Si _0.105 ) ₁₃ and La _0.65 Ce _0.35 (Fe _0.860 Mn _0.025 Si _0.115 ) ₁₃ . Show. Regarding the adiabatic temperature change, similarly to the magnetic entropy change, if the Fe concentration is the same, even if the Curie temperature is controlled to be lowered, a value almost equal to or higher than that before the substitution can be obtained.

On the other hand, La _0.65 Ce _0.35 (Fe _0.860 Mn _0.025 Si _0.115 ) ₁₃ is about 5 when 2T magnetic field is applied.
K, but adiabatic temperature change of about 4 K was observed when 1 T magnetic field was applied. This value is the applied magnetic field of La (Fe _0.88 Si _0.12 ) ₁₃ and La _0.8 Ce _0.2 (Fe _0.880 Mn _0.015 Si _0.105 ) ₁₃
It is almost the same as the adiabatic temperature change at T. In other words, large adiabatic temperature change is obtained by _{La 1-z Ce z (Fe} x Mn y Si 1-xy) 13 of Ce and Mn any temperature 190 K from 70K by controlling the amount of substitution.

La _1-z Ce _z (Fe _x Mn _y Si _1-xy ) ₁₃ has excellent magnetocaloric properties in a relatively low magnetic field at any temperature from 70 K to 190 K by controlling the substitution amount of Ce and Mn. Show.

La(Fe_0.88Si_0.12)₁₃、La_0.8Ce_0.2(Fe_0.880Mn_0.015Si_0.105)₁₃およびLa_0.65Ce_0.35 (Fe_0.860Mn_0.025Si_0.115)₁₃のキュリー温度とRCP。

Curie temperature and RCP of La (Fe _0.88 Si _0.12 ) ₁₃ , La _0.8 Ce _0.2 (Fe _0.880 Mn _0.015 Si _0.105 ) ₁₃ and La _0.65 Ce _0.35 (Fe _0.860 Mn _0.025 Si _0.115 ) ₁₃ .

Therefore, La _1-z Ce _z (Fe _x Mn _y Si _1-xy ) ₁₃ is from 70K to 190
It is promising as a magnetic refrigeration material in the K temperature range.

Thermomagnetic curves of La (Fe _0.89-y Mn _y Si _0.11 ) ₁₃ at y = 0.0, 0.1, 0.2 and 0.3. Temperature dependence of magnetic entropy change of La (Fe _0.89-y Mn _y Si _0.11 ) ₁₃ at y = 0.0, 0.1, 0.2 and 0.3. _{La (Fe 0.88 Mn y Si 0.12} -y) 13 thermomagnetic curve of y = 0.000 and 0.015 for. Temperature dependence of magnetic entropy change of La (Fe _0.88 Mn _y Si _0.12-y ) ₁₃ at y = 0.000, 0.010 and 0.015. Thermomagnetic curves of La _1-z Ce _z (Fe _0.88 Si _0.12 ) ₁₃ at z = 0.0, 0.1, 0.2 and 0.3. Temperature dependence of magnetic entropy change of La _1-z Ce _z (Fe _0.88 Si _0.12 ) ₁₃ at z = 0.0, 0.1, 0.2 and 0.3. Temperature dependence of magnetic entropy change of La (Fe _0.88 Si _0.12 ) ₁₃ , La _0.8 Ce _0.2 (Fe _0.880 Mn _0.015 Si _0.105 ) ₁₃ and La _0.65 Ce _0.35 (Fe _0.860 Mn _0.025 Si _0.115 ) ₁₃ . Temperature dependence of adiabatic temperature change of La (Fe _0.88 Si _0.12 ) ₁₃ , La _0.8 Ce _0.2 (Fe _0.880 Mn _0.015 Si _0.105 ) ₁₃ and La _0.65 Ce _0.35 (Fe _0.860 Mn _0.025 Si _0.115 ) ₁₃ .

Claims (2)

In NaZn ₁₃ type _{La (Fe x Si 1-x} ) 13, the La is partially substituted with Ce, or / and Si was partially replaced with Mn, the composition _{formula: La 1-z Ce z (} Fe x Mn y Si 1 _-xy ) ₁₃ (0.86 ≦ x ≦ 0.88, 0 ≦ y ≦ 0.03, 0 ≦ z ≦ 0.035
A magnetic refrigeration working material represented by 0 <(y + z) ) or a magnetic refrigeration working material of the hydrogen absorbing compound. The magnetic refrigeration working material NaZn ₁₃ type La (Fe _x Si _1-x ) ₁₃ (0.86 ≦ x ≦ 0.88) and the magnetic refrigeration working material according to claim 1 are used by changing the composition and using two or more kinds, the range of temperature 70K of 200K, the composition formula: is represented by _{La 1-z Ce z (Fe} x Mn y Si 1-xy) 13 (0.86 ≦ x ≦ 0.88,0 ≦ y ≦ 0.03,0 ≦ z ≦ 0.035) A magnetic refrigeration method, wherein cooling control is performed using a magnetic refrigeration working material of one composition system.

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