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Magnetic refrigeration material compound with high magnetic entropy change and its preparation method

A technology of magnetic refrigeration materials and compounds, applied in the direction of magnetic materials, heat exchange materials, chemical instruments and methods, etc., can solve problems such as unreported processes, achieve the effects of controlling oxygen content, simple preparation process, and improving inherent characteristics

Inactive Publication Date: 2014-07-23
CHINA JILIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the solid-state reaction method is the main method for rare earth oxide magnetic refrigeration materials, but almost all literature research works use the traditional high-temperature firing process in the atmospheric atmosphere, and the process in the reducing atmosphere has not been reported.
In addition, the doping elements involved in the literature are mainly divalent alkaline earth metal elements, and there are few patents and literature reports on the use of gallium Ga, thulium Tm, rolled Gd and indium In as doping elements.

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  • Magnetic refrigeration material compound with high magnetic entropy change and its preparation method
  • Magnetic refrigeration material compound with high magnetic entropy change and its preparation method

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preparation example Construction

[0023] Different from the preparation of traditional magnetic refrigeration materials, the present invention uses manganese perovskite LaMnO 3 The structural system is the matrix, and calcium Ca and thulium Tm are used as the matrix component ions. A solid-state reaction method is used to directly introduce auxiliary doping ions M with unequal Mn sites into the raw material formula to prepare a high magnetic entropy change. The magnetic refrigeration material (La 0.7 Ca 0.2 T m 0.1 )Mn 1-x m x o 3 (03+ / Mn 4+ Valence balance, so as to achieve the purpose of controlling the number of point defects in the crystal structure.

[0024] The following specifically describes the magnetic refrigeration material of the present invention (La 0.7 Ca 0.2 T m 0.1 )Mn 1-x m x o 3 preparation process.

[0025] The present invention adopts the solid phase reaction method for batching to prepare the mixture used for firing. Specifically, a certain amount of La 2 o 3 Dry at a tem...

Embodiment 1

[0032] First, a certain amount of La 2 o 3 Dry at 600°C for 10 hours (h) to remove crystal water. Weigh the dried La according to the atomic ratio La: Ca: Tm: Mn: Ga = 07: 0.2: 0.1: 0.99: 0.01 2 o 3 , MnCO 3 , CaCO 3 , Tm(NO 3 ) 3 and Ga(NO 3 ) 3 , formulated into a mixture. Preferably, before preparing the mixture, the MnCO 3 and CaCO 3 For drying, for example, MnCO 3 and CaCO 3 Dry at a temperature of 100°C to 300°C for 6 to 12 hours. Then, add absolute ethanol according to the weight ratio of the mixture to absolute ethanol at 1:1.5, and ball mill and mix for 4 hours in a planetary ball mill with a rotational speed of 300 rpm (r / min), to obtain a ball mill. Afterwards, the prepared ball mill was dried at a temperature of 100° C. for 30 h. Put the dried mixture into a crucible (such as alumina crucible, graphite crucible, etc.), and calcinate at 1000° C. for 24 hours to obtain a precursor. Then, after the precursor is ground repeatedly, it is pressed under a ...

Embodiment 2

[0036] First, a certain amount of La 2 o 3 After drying at 700 °C for 7 h, the MnCO 3 、TiO 2 and CaCO 3 Dry at 100°C for 12h. Then, according to the atomic ratio La:Ca:Tm:Mn:Ti=07:0.2:0.1:0.9:0.1, weigh the dried La 2 o 3 , MnCO 3 , CaCO 3 and TiO 2 and Tm(NO 3 ) 3 , formulated into a mixture. Afterwards, the prepared mixed material and absolute ethanol were added into absolute ethanol at a weight ratio of 1:1, and then ball milled and mixed for 4 hours in a planetary ball mill with a rotational speed of 300 r / min to obtain a ball mill. Afterwards, the prepared ball mill was dried at a temperature of 150° C. for 20 h. Next, the dried mixture was put into an alumina crucible, and calcined at 1100° C. for 20 hours to obtain a precursor. Afterwards, the precursor is repeatedly ground, and pressed under a pressure of 200 MPa into a small round block with a diameter of about 20 mm and a thickness of about 5 mm to obtain a mixture for firing. Put the round block-shaped...

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Abstract

The invention discloses a magnetic refrigeration material compound with a high magnetic entropy change and its preparation method. With a chemical composition formula of (La0.7Ca0.2Tm0.1)Mn1-xMxO3, the magnetic refrigeration material compound in the invention employs the structural system of manganese perovskite LaMnO3 as a matrix, adopts Ca and Tm as matrix component ions, and takes M as a point defect controlled doping ion, wherein, the x is greater than 0 and smaller than or equal to 0.1. And the greatest magnetic entropy change of the compound is greater than or equal to 5.0J / kg.K under a 5T magnetic field. In the invention, doping of ions of different valences and atmosphere treatment are employed to regulate and control point defects. The magnetic refrigeration performance of the compound is improved by controlling electron transport in a crystal structure and interionic spinning electron coupling effect, thus obtaining a high Curie transition point and good material usage performance. Therefore, the magnetic entropy change value of the compound can be enhanced by about an order of magnitude, and the compound of the invention has the characteristics of high material stability, no toxic or side effect, simple operation process, and low cost, etc.

Description

technical field [0001] The invention relates to a high magnetic quotient variable magnetic refrigeration material and a preparation method thereof, in particular to a high magnetic entropy variable magnetic refrigeration material obtained by utilizing the substitution effect of ionic elements and burning in a high-temperature atmosphere and a preparation method thereof. Background technique [0002] The rare earth oxide system with perovskite structure shows unique optical, electrical and magnetic transport properties and excellent magnetoresistance effect, catalytic performance and magnetocaloric effect due to the inherent strong carrier-spin coupling effect, so it is It is widely used in many fields such as magnetic refrigeration, high temperature heating materials, solid resistors and redox catalysis. Especially in recent years, due to the serious impact of Freon refrigerant on the ecological environment (destruction of the atmospheric ozone layer), according to the Montr...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09K5/14H01F1/053
Inventor 张朋越葛洪良彭晓领洪波杨杭福刘婷婷
Owner CHINA JILIANG UNIV
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