Magnetocaloric effect and critical behaviors of R2NiMnO6 (R=Eu and Dy) double perovskite oxides
Magnetocaloric effect and critical behaviors of R2NiMnO6 (R=Eu and Dy) double perovskite oxides
复制标题
R2NiMnO6（R=Eu和Dy）双钙钛矿氧化物的磁热效应和临界行为
DOI：
10.1016/j.jallcom.2018.02.327
复制
发表时间：
2018
影响因子：
6.2
通讯作者：
Cheng Zhao-Hua
中科院分区：
文献类型：
--
作者：
Su Lei;Zhang Xiang-Qun;Dong Qiao-Yan;Ke Ya-Jiao;Hou Kai-Yue;Liu Cheng-Shi;Cheng Zhao-Hua
研究了Eu 2NiMnO 6和Dy 2NiMnO 6双钙钛矿氧化物的磁热效应和临界行为。在0 ~ 7 T的磁场范围内，磁熵变的最大值（|Δ S M max|）分别达到4.0J/kgK和5.2J/kgK，相对制冷量（RCP）分别为241.5J/kg和385.1J/kg。相对较高的|Δ S M|和RCP的研究结果表明，这类双钙钛矿型氧化物可作为在较宽温度范围内工作的磁制冷剂候选材料。采用修正的Arrott图、Kouvel-Fisher法和临界等温线分析等方法估算了Eu 2NiMnO 6的临界指数（β、γ和δ）和Tc。这些临界指数不仅服从Widom标度关系δ= 1+ γ/β，而且满足标度方程M（H，ε）= ε β f±（H/ε β+ γ），其中ε=（T-TC）/TC，f+（T> TC）和f-（T<TC）是正则解析函数.因此，推导出的临界指数相当准确。此外，有效临界指数的温度变化类似于无序铁磁体，这与从反磁化率T C以上观察到的Griffiths相行为相匹配。
We have investigated the magnetocaloric effects and critical behaviors of Eu 2 NiMnO 6 and Dy 2 NiMnO 6 double perovskite oxides. For a magnetic field varying from 0 to 7 T, the maximum values of the magnetic entropy change (| Δ S M max|) reach 4.0 J/kg K and 5.2 J/kg K, and the relative refrigeration capacity (RCP) values are 241.5 J/kg and 385.1 J/kg for Eu 2 NiMnO 6 and Dy 2 NiMnO 6, respectively. The relatively high values of| Δ S M| and RCP suggest that these double perovskite oxides can be used as candidates of magnetic refrigerants working in a wide temperature range. Various techniques such as modified Arrott plot, Kouvel-Fisher method and critical isotherm analysis are used to estimate the critical exponents (β, γ and δ) as well as T C for Eu 2 NiMnO 6. These critical exponents not only obey the Widom scaling relation δ= 1+ γ/β, but also fulfill the scaling equation M (H, ε)= ε β f±(H/ε β+ γ) where ε=(T–T C)/T C, f+(T> T C) and f-(T< T C) are the regular analytic functions. Therefore, the deduced critical exponents are reasonably accurate. Moreover, temperature variation in effective critical exponents resemble with those for disordered ferromagnet, which matches with the Griffiths-like phase behavior observed from inverse magnetic susceptibility just above T C.