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71.
MAGNETIC PROPERTIES AND CRYSTALLIZATION OF THE RAPIDLY QUENCHED (Fe1-xNdx) 81.5B18.5 ALLOYS
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Magnetic properties and crystallization behaviors of amorphous (Fe1-xNdx) 81.5B18.5 alloys were studied. The crystallization temperature is found to rise at first and then drop monotonically with x, having a maximum value of 976K at x=0.11 (9at% Nd). The (Fe1-xNdx) 81.5B18.5 alloys prepared at a quenching rate of vs = 6.6m /s are amorphous, and exhibit good glass formability. Both the coercive field Hc and energy product (BH)max depend strongly on Nd concentration. Amorphous (Fe1-xNdx) 81.5B18.5 alloys with higher Nd concentration have a high coercive field at low temperature, due to the large random uniaxial anisotropy of Nd. The room-temperature Hc and (BH)max obtained on optimal annealing con-ditions show two maxima as a function of Nd concentration x. The highest room-temperature coercive field Hc =22 kOe within the Nd concentrations around x=0.368 and the maximum energy product(RH)max= 13.3 MG·Oe at x =0.055 are observed. The hard magnetic properties of these crystallized samples are related to the presence of the bard magnetic Nd2Fe14B phase. 相似文献
72.
EFFECT OF MANGANESE SUBSTITUTION IN R2AlFe16-x Mnx(R=Y,Ho,Nd AND Pr)COMPOUNDS ON STRUCTURAL AND MAGNETIC PROPERTIES
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The structural and magnetic properties of R2AlFe16-xMnx(0≤x≤8 for Y,Ho,0≤x≤10 for Pr, 0≤x≤16 for Nd)compounds have been investigated by means of X-ray diffraction and magnetization measurements.The R2AlFe16-xMnx compounds have a hexagonal Th2Ni17-type structure for R=Y and Ho, and a rhombohedral Th2Zn17-type structure for Nd and Pr.With increasing x,the unit-cell volumes have a small increase initially,followed by a greater linear increase.The Curie temperature and the saturation magnetizati on of these compounds show marvelous drop with increasing x.Compensation point was observed in the temperature dependence of the magnetization for Ho2AlFe12Mn4 compound. 相似文献
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77.
基于磁二色效应的光发射电子显微镜磁成像技术是研究薄膜磁畴结构的一种重要研究手段,具有空间分辨率高、可实时成像以及对表面信息敏感等优点.以全固态深紫外激光(波长为177.3 nm;能量为7.0 eV)为激发光源的光发射电子显微技术相比于传统的光发射电子显微镜磁成像技术(以同步辐射光源或汞灯为激发源),摆脱了大型同步辐射光源的限制;同时又解决了当前阈激发研究中由于激发光源能量低难以实现光电子直接激发的技术难题,在实验室条件下实现了高分辨磁成像.本文首先对最新搭建的深紫外激光-光发射电子显微镜系统做了简单介绍.然后结合超高真空分子束外延薄膜沉积技术,成功实现了L10-FePt垂直磁各向异性薄膜的磁畴观测,其空间分辨率高达43.2 nm,与利用X射线作为激发源的光发射电子显微镜磁成像技术处于同一量级,为后续开展高分辨磁成像提供了便利.最后,重点介绍了在该磁成像技术方面取得的一些最新研究成果:通过引入Cr的纳米"台阶",成功设计出FePt的(001)与(111)双取向外延薄膜;并在"台阶"区域使用线偏振态深紫外激光观测到了磁线二色衬度,其强度为圆二色衬度的4.6倍.上述研究结果表明:深紫外激光-光发射电子显微镜磁成像技术在磁性薄膜/多层膜体系磁畴观测方面具备了出色的分辨能力,通过超高真空系统与分子束外延薄膜制备系统相连接,可以实现高质量单晶外延薄膜制备、超高真空原位传输和高分辨磁畴成像三位一体的功能,为未来磁性薄膜材料的研究提供了重要手段. 相似文献
78.
Using x-ray diffraction and magnetic measurements, we have studied the structural and magnetic properties of Dy2Co17-xMnx (x=0∽5) compounds with a rhombohedral Th2Zn17-type structure. With an increasing Mn concentration x, the unit-cell volume V was found to increase linearly. The Curie temperature Tc decreases linearly, and the saturation magnetization Ms at 5K first increases slightly for x<1, then decreases rapidly for x>1 with a further increase of Mn concentration x. In compounds for x=1~3, a spin reorientation was found. A magnetic diagram of the compounds is given. 相似文献
79.
Change in the magnetic ground state of LaFe11.4Al1.6 compound by the substitution of Mn for Fe
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The structure and magnetic properties of La(Fe_{1-x}Mn_x)_{11.4}Al_{1.6} (0≤x≤0.25)compounds have been studied. The NaZn_{13}-type structure is preserved and the lattice parameter increases linearly with increasing the Mn concentration. The magnetic ground state changes from the antiferromagnetic to the spin-glass or the cluster-glass state by the substitution of Mn for Fe. Furthermore, a field-induced transition from cluster glass to ferromagnet is found for the samples with x=0.05 and 0.10. 相似文献
80.
Magnetism and magnetic entropy changes in LaFe11A12Cx(x=0.0, 0.2 and 0.5) compounds have been investigated.The Curie temperature TC is conveniently controlled from 200K to room temperature by varying the carbon concentration.Large magnetic entropy change is obtained over a wide temperature range due to the high magnetization and the drastic decrease in the magnetization around TC.The large magnetic entropy change in wide temperature range,low cost and the convenience of controlling TC suggest that the LaFe11Al2Cx compounds are promising candidates for magnetic refrigerants in the corresponding temperature range. 相似文献