Magnetic and thermal properties of the (Gd 1- x Tb x ) 3Al 2 compounds were studied as potential magnetic refrigerant materials which are used in magnetic refrigeration near room temperature at low magnet...Magnetic and thermal properties of the (Gd 1- x Tb x ) 3Al 2 compounds were studied as potential magnetic refrigerant materials which are used in magnetic refrigeration near room temperature at low magnetic field. The compounds (Gd 1- x Tb x ) 3Al 2 with x =0, 0.1, 0.2 and 0 3 exhibit a second order magnetic transition. Curie temperature varies from 255 K for x =0.3 to 280 K for x =0. The maximum of the isothermal magnetic entropy change Δ S increases by substituting Tb element for Gd element. Δ S max =18.9 kJ·m -3 ·K -1 for x =0.1 by changing the magnetic field from 0 to 1 T.展开更多
磁制冷技术的发展取决于磁热效应材料的研究进展.其中,具有各向异性磁热效应的材料可以用于旋转磁制冷技术,有利于制冷装置的大幅度简化.本文研究了快淬带Ho Co Si化合物的磁性、磁热效应及磁各向异性.在Tt=5.7 K以下的低温,Ho Co Si快...磁制冷技术的发展取决于磁热效应材料的研究进展.其中,具有各向异性磁热效应的材料可以用于旋转磁制冷技术,有利于制冷装置的大幅度简化.本文研究了快淬带Ho Co Si化合物的磁性、磁热效应及磁各向异性.在Tt=5.7 K以下的低温,Ho Co Si快淬带铁磁和螺旋磁性共存,随着温度的升高,在TC=13.7 K处发生了铁磁(FM)到顺磁(PM)的二级相变.XRD和SEM都显示出Ho Co Si具有择优取向.为了获得大的磁热效应并确定择优取向对磁性和磁热效应的影响,对10 m/s下Ho Co Si快淬带在磁场平行和垂直织构方向时居里温度附近的等温磁化曲线进行分析,并计算了对应的磁熵变和磁制冷能力.在外磁场μ0H=0—5 T的磁场变化时,磁场平行和垂直织构方向的最大磁熵变值–ΔSM分别为22 J/(kg·K)和12 J/(kg·K);制冷能力RC(RCP)分别为360(393.8)J/kg和160(254.4)J/kg,表明10 m/s的Ho Co Si快淬带具有大的磁热效应和明显的磁各向异性,有望实现旋转样品磁制冷技术.展开更多
The crystal structure, itinerant-electron metamagnetic transition (IEMT) and magnetocaloric effect (MCE) in the iron-based rare-earth intermetallic compound La0.8Ce0.2Fe11.4Si1.6 have been investi- gated. The powder X...The crystal structure, itinerant-electron metamagnetic transition (IEMT) and magnetocaloric effect (MCE) in the iron-based rare-earth intermetallic compound La0.8Ce0.2Fe11.4Si1.6 have been investi- gated. The powder X-ray diffraction revealed that the ingot of La0.8Ce0.2Fe11.4Si1.6 annealed at 1373 K in vacuum for only 5 days could be crystallized in the cubic NaZn13-type structure. The La0.8Ce0.2Fe11.4Si1.6 compound exhibited giant values of the isothermal entropy change ?SM around the Curie temperature TC (about 186 K). And the maximum value ΔS M max is about 78.29 J/(kg·K) under a field change of 0—3 T, which can be calculated by the magnetization iso- therms around TC. Such a large MCE is attributed to the sharp change of magnetization and susceptibility around TC and the first-order magnetic transition of field-induced IEMT above TC.展开更多
文摘Magnetic and thermal properties of the (Gd 1- x Tb x ) 3Al 2 compounds were studied as potential magnetic refrigerant materials which are used in magnetic refrigeration near room temperature at low magnetic field. The compounds (Gd 1- x Tb x ) 3Al 2 with x =0, 0.1, 0.2 and 0 3 exhibit a second order magnetic transition. Curie temperature varies from 255 K for x =0.3 to 280 K for x =0. The maximum of the isothermal magnetic entropy change Δ S increases by substituting Tb element for Gd element. Δ S max =18.9 kJ·m -3 ·K -1 for x =0.1 by changing the magnetic field from 0 to 1 T.
文摘磁制冷技术的发展取决于磁热效应材料的研究进展.其中,具有各向异性磁热效应的材料可以用于旋转磁制冷技术,有利于制冷装置的大幅度简化.本文研究了快淬带Ho Co Si化合物的磁性、磁热效应及磁各向异性.在Tt=5.7 K以下的低温,Ho Co Si快淬带铁磁和螺旋磁性共存,随着温度的升高,在TC=13.7 K处发生了铁磁(FM)到顺磁(PM)的二级相变.XRD和SEM都显示出Ho Co Si具有择优取向.为了获得大的磁热效应并确定择优取向对磁性和磁热效应的影响,对10 m/s下Ho Co Si快淬带在磁场平行和垂直织构方向时居里温度附近的等温磁化曲线进行分析,并计算了对应的磁熵变和磁制冷能力.在外磁场μ0H=0—5 T的磁场变化时,磁场平行和垂直织构方向的最大磁熵变值–ΔSM分别为22 J/(kg·K)和12 J/(kg·K);制冷能力RC(RCP)分别为360(393.8)J/kg和160(254.4)J/kg,表明10 m/s的Ho Co Si快淬带具有大的磁热效应和明显的磁各向异性,有望实现旋转样品磁制冷技术.
基金This work was supported by the National Natural Science Foundation of China （Grant No. 50164003）.
文摘The crystal structure, itinerant-electron metamagnetic transition (IEMT) and magnetocaloric effect (MCE) in the iron-based rare-earth intermetallic compound La0.8Ce0.2Fe11.4Si1.6 have been investi- gated. The powder X-ray diffraction revealed that the ingot of La0.8Ce0.2Fe11.4Si1.6 annealed at 1373 K in vacuum for only 5 days could be crystallized in the cubic NaZn13-type structure. The La0.8Ce0.2Fe11.4Si1.6 compound exhibited giant values of the isothermal entropy change ?SM around the Curie temperature TC (about 186 K). And the maximum value ΔS M max is about 78.29 J/(kg·K) under a field change of 0—3 T, which can be calculated by the magnetization iso- therms around TC. Such a large MCE is attributed to the sharp change of magnetization and susceptibility around TC and the first-order magnetic transition of field-induced IEMT above TC.
