文章信息/Info

Title:

Magnetic Properties and Magnetocaloric Effects in R PdAl (R=Gd Er)

作者:

許志一; 沈俊; 沈保根

（1．中國(guó)科學(xué)院物理研究所 磁學(xué)國(guó)家重點(diǎn)實(shí)驗(yàn)室，北京 100190）��
（2．中國(guó)科學(xué)院理化技術(shù)研究所 低溫重點(diǎn)實(shí)驗(yàn)室，北京 100190）

Author(s):

XU Zhiyi��1;  SHEN Jun��2;  SHEN Baogen��1

(1. State Key Laboratory for Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China)��
(2. Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of��Sciences, Beijing 100190, China)

關(guān)鍵詞:

R PdAl化合物; 結(jié)構(gòu); 磁性; 磁熵變; 磁熱效應(yīng)

DOI:

10.7502/j.issn.1674-3962.2013.02.03

摘要:

低溫退火的LTM R PdAl和高溫退火的HTM R PdAl分別具有正交TiNiSi型和六角ZrNiAl型結(jié)構(gòu)。綜述了磁場(chǎng)和溫度變化對(duì)LTM R PdAl和HTM R PdAl化合物磁性和磁熱效應(yīng)的影響。實(shí)驗(yàn)結(jié)果表明，LTM R PdAl化合物均是反鐵磁性的，當(dāng)R=Gd，Tb，Dy，Ho，Er時(shí)，奈爾溫度T N分別為31，45，21，10和10 K。對(duì)于HTM R PdAl化合物，當(dāng)R=Tb，Ho，Er時(shí)是反鐵磁性的，T N分別為43，12和5 K，而當(dāng)R=Gd，Dy時(shí)是鐵磁性的，其居里溫度分別為T C=49，25 K。反鐵磁R PdAl化合物均呈現(xiàn)磁場(chǎng)誘導(dǎo)的反鐵磁鐵磁變磁轉(zhuǎn)變。對(duì)HTM R PdAl（�玆=Ho，Er）化合物，由于弱的反鐵磁耦合，在低磁場(chǎng)下呈現(xiàn)出高的飽和磁化強(qiáng)度，從而產(chǎn)生大的磁熱效應(yīng)，在0~5 T磁場(chǎng)變化下的最大磁熵變值和制冷能力分別高達(dá)20��6，24 3 J/kg·K和386，299 J/kg，是優(yōu)異的低溫磁制冷材料。��

Abstract:

In this article, the investigation progress is reviewed in magnetic field and temperature dependences of the magnetic properties and magnetocaloric effects (MCEs) for �玆�玃dAl compounds with the orthorhombic TiNiSi�瞭ype (LTM) and the hexagonal ZrNiAl�瞭ype (HTM) structures. The LTM�勃玆�玃dAl (�玆��=Gd, Tb, Dy, Ho and Er) compounds are found to be antiferromagnet with the Néel temperature �玊���璑=31, 45, 21, 10 and 10 K, respectively. It has been confirmed that the HTM�勃玆�玃dAl (�玆��=Tb, Ho and Er) compounds undergo the antiferromagnetic (AFM)�瞭o�瞤aramagnetic (PM) transition at �玊���璑=43, 12 and 5 K, while the HTM�勃玆�玃dAl (�玆��=Gd and Dy) compounds undergo the ferromagnetic (FM)�瞭o�睵M transition at their respective Curie temperature, which is �玊���瑿 =49 K and 25 K, respectively. A field�瞚nduced metamagnetic transition from AFM to FM state is observed below �玊���璑 in the antiferromagnetic �玆�玃dAl. For the HTM�勃玆�玃dAl (�玆��=Ho and Er) compounds, a small magnetic field can induce an FM�瞝ike state due to a weak AFM coupling, which leads to a high saturation magnetization, and gives rise to a large MCE around �玊���璑. The maximum value of magnetic entropy change (Δ�玈���璏) reaches -20��6 and -24��3 J/kg·K with a refrigerant capacity (�玆C��) value of 386 and 299 J/kg around �玊���璑 for a field change of 0~5 T, respectively. The large Δ�玈���璏 and considerable �玆C�� suggest that HTM�勃玆�玃dAl may be an appropriate candidate for magnetic refrigerant in low temperature ranges.��