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1.
利用直流电沉积法在多孔阳极氧化铝模板中制备出了一系列Fe100-xPdx磁性纳米线阵列. Pd的增加使纳米线的总体磁性降低,各向异性和矫顽力也发生了较大的变化. 当Pd含量高达x=30时,纳米线仍有相当高的矫顽力(7.48 kA/m)和较明显的各向异性,但当Pd的含量增加到50%时,纳米线的易磁化方向由平行线的方向反转到垂直线的方向. 实验证明,这是由于在Fe80Pd20和Fe70Pd30中连续的磁性相在Fe50Pd50纳米线中变成了与非磁性相相互间隔的非连续片状结构. 片状磁性相的形状各向异性使易磁化方向转变到垂直纳米线轴的方向. 从生长动力学的角度对Fe50Pd50纳米线中这种片状的形成进行了解释. 关键词: 纳米线 电化学沉积 磁性  相似文献   

2.
史慧刚  付军丽  薛德胜 《物理学报》2005,54(8):3862-3866
利用电化学沉积方法在阳极氧化铝模板中制备了Fe89.7P10.3非晶 合金纳 米线阵列.利用x射线衍射仪、透射电子显微镜、振动样品磁强计和穆斯堡尔谱仪研究了样品的结构和磁性,发现纳米线阵列是非晶结构,且拥有垂直磁各向异性和高的矫顽力,Hc =304×104A/m.纳米线内部的平均超精细场和平均同质异能移分别为2 15×106 A/m和007 mm/s;而纳米线末端的平均超精细场(233×106 A/m )大于内 部的值,平均同质异能移(004 mm/s)小于内部的值.另外,纳米线内部Fe原子磁矩与线轴的夹角约为16°,而在纳米线末端Fe原子磁矩与线轴的夹角约为28°.这些结果表明,由于形状各 向异性,在纳米线中实现了无序非晶合金磁矩的有序排列. 关键词: 非晶合金 纳米线阵列 垂直磁各向异性 穆斯堡尔谱  相似文献   

3.
利用直流电化学沉积法通过调节沉积参数在多孔阳极氧化铝模板中制备出了束状形貌的Co89Cu11纳米线阵列.结构分析表明,束状结构就是沿纳米线长轴方向密集排列的堆垛层错,根据CoCu纳米线的生长机理对这种结构的形成进行了解释.在相同成分比的情况下,该结构的Co89Cu1纳米线阵列具有明显优于一般结构的矩形比(S=096),说明该结构的纳米线阵列的形状各向异性远好于一般结构.通过磁性测 关键词: 磁性纳米线 电化学沉积 反磁化机理  相似文献   

4.
利用电化学沉积方法在同一种富Co2+溶液Co2+/Cu2+=10∶1中,利用不同的沉积电位成功地制备了一系列不同成分(x=0.38—0.87)和复合相结构的CoxCu1-x纳米线阵列.发现随着纳米线中Cu含量的变化,CoxCu1-x纳米线的复相结构随之发生规律的变化,最终导致纳米线的磁性也随之规律的变化.随着纳米线中Cu含量的不断增加,一部分Cu与Co形成面心立方结构(fcc)的CoCu固溶体,减弱了磁晶各向异性与形状各向异性的竞争,从而提高样品的方形度;一部分Cu以fcc结构的Cu单质的形式存在于纳米线中,并随着Cu颗粒大小的不同分别起到破坏磁晶各向异性和钉扎畴壁的作用,从而增加纳米线的方形度和矫顽力.对比不同成分的样品,发现CoxCu1-x纳米线的方形度和矫顽力的最大值分别出现在Co75Cu25和Co60Cu40中,并且由于其特殊的复相结构致使它们的值要好于相同直径的单相结构的结果. 关键词: 纳米线 电化学沉积 磁性  相似文献   

5.
铁镍合金纳米线阵列的制备与穆斯堡尔谱研究   总被引:4,自引:0,他引:4       下载免费PDF全文
刘青芳  王建波  彭勇  曹兴忠  薛德胜 《物理学报》2001,50(10):2008-2011
用交流电化学沉积方法在阳极氧化铝模板中成功地制备了直径约16nm,长度4μm的Fe1-xNix(0关键词: 纳米线阵列 穆斯堡尔谱 铁镍合金  相似文献   

6.
利用直流电沉积法在多孔阳极氧化铝模板中制备出了一系列Fe100-xPdx磁性纳米线阵列. Pd的增加使纳米线的总体磁性降低,各向异性和矫顽力也发生了较大的变化. 当Pd含量高达x=30时,纳米线仍有相当高的矫顽力(7.48 kA/m)和较明显的各向异性,但当Pd的含量增加到50%时,纳米线的易磁化方向由平行线的方向反转到垂直线的方向. 实验证明,这是由于在Fe80Pd20 和Fe70Pd30中连续的磁性相在Fe50Pd50纳米线中变成了与非磁性相相互间隔的非连续片状结构. 片状磁性相的形状各向异性使易磁化方向转变到垂直纳米线轴的方向. 从生长动力学的角度对Fe50Pd50纳米线中这种片状的形成进行了解释.  相似文献   

7.
电化学沉积Fe单晶纳米线生长中的取向控制   总被引:6,自引:0,他引:6       下载免费PDF全文
利用电化学沉积方法,发现了一种能够动态地控制铁纳米线生长方向的沉积方法,利用该方法沉积了包括[110]取向,[200]取向及非晶态三种结构和取向的一维Fe纳米线阵列.对于三种纳米线阵列,测量了它们的磁特性,分析发现具有[200]择优取向纳米线阵列的方形度,各向异性特性和矫顽力都比[110]取向阵列有很大的改善. 关键词: 磁性纳米线 电化学沉积 取向控制  相似文献   

8.
本文报道了有关溅射氧化铁薄膜磁性能的系统研究,特别着重于矫顽力的温度依赖关系和矫顽力随不同氧化铁相的变化。从理论分析与实验测量结果的对比中,给出了形状各向异性、磁晶各向异性及应力各向异性各自对Fe3O4薄膜、γ-Fe2O3薄膜及二者混合相薄膜的贡献,并且得到了Fe3O4薄膜和γ-Fe2O3薄膜的磁晶各向异性常数K1的温度依赖关系曲线。 关键词:  相似文献   

9.
张辉  曾德长  刘仲武 《物理学报》2011,60(6):67503-067503
研究了Fe0.81Ga0.19合金单晶沿[100]方向的磁机械效应和磁致伸缩效应.基于Stoner-Wohlfarth模型,通过数值计算获得了在压应力和外磁场联合作用下磁化强度的方向余弦.研究表明,随着压应力的增加,退磁态下合金中的磁各向异性会由三轴各向异性向双轴各向异性转变.这使得合金中 90° 畴的体积分数增加,导致磁致伸缩效应增大. 关键词: FeGa合金 磁机械效应 巨磁致伸缩效应  相似文献   

10.
陈文兵  韩满贵  邓龙江 《物理学报》2011,60(1):17507-017507
使用电化学脉冲沉积法制备了磁晶各向异性易磁化方向(c轴)垂直纳米线长轴方向的钴纳米线.受到磁晶各向异性、静磁相互作用等因素与形状各向异性相互竞争的结果,纳米线阵列的磁滞回线显示出较弱的磁各向异性.此外,在2—18 GHz频率范围内,纳米线/石蜡复合材料的介电色散谱的虚部在5 GHz处有一个主峰,在10 GHz附近有一个较弱的峰;德拜弛豫特性和材料的电导率对这两个峰的形成均有贡献.同时,其磁导率色散谱的虚部在频率为6.1 GHz处有一个主峰,在10 GHz以上有两个较微弱的峰. 前一个峰源于自 关键词: 钴纳米线 介电色散谱 磁导率色散谱 微波吸收剂  相似文献   

11.
Fe-30%Pd alloys in ribbon and nanowire geometry have been prepared. Ribbon samples were produced by the melt-spinning technique in the Ar environment. FePd nanowires, having about 35 nm in diameter, 105 nm inter-nanowires distance and around 4 μm in length, were synthesized into nanoporous anodic alumina membranes as templates. Energy dispersive X-ray microanalysis of ribbons shows an average atomic composition of Fe (73.2%) and Pd (26.8%). The X-ray diffraction at RT analysis was performed on both surfaces, free and wheel side, of the melt-spun ribbon. It shows the coexistence of two phases: fct and bct FePd, but with differences between both surfaces consisting the existence of Fe oxides (Fe2O3 and Fe3O4) and a textured 200 reflection in the free side. Heating and cooling thermomagnetic curves exhibit a reversible behaviour from RT to 720 K, but around 770 K a clear irreversible transformation takes place.  相似文献   

12.
Fe0.95Pd0.05 nanowires were fabricated by the electrodeposition in porous anodic aluminum oxide templates and post-annealed at 300–700 °C. Transmission electron microscopy observations demonstrated the isolated nanowires to have polycrystalline structure. Magnetic measurements, however, showed improvement of both coercivity and squareness with the addition of 5 at% Pd in the Fe nanowires as well as proper annealing temperatures of about 500 °C.  相似文献   

13.
采用磁控溅射法制备了Pd/Fe和Pd1-xFex/Fe多层膜.利用变换梯度磁强计测量了样品的Ms.发现层间耦合是铁磁性的,Ms具有长程振荡,周期为4ML.振荡的相位和周期在Pd0.966Fe0.034/Fe和Fd0.944Fe0.056/Fe系统中保持不变.就Pd/Fe多层膜中是否存在内层的Pd负极化和长程的铁磁耦合振荡进行了讨论,并分析了不同计算结果以及理论计算与实验结果之间存在差异的原因. 关键词:  相似文献   

14.
15.
Klebsiella oxytoca BAS‐10 ferments citrate to acetic acid and CO2, and secretes a specific exopolysaccharide (EPS), which is able to bind different metallic species. These biomaterials may be used for different biotechnological purposes, including applications as innovative green biogenerated catalysts. In production of biogenerated Pd species, the Fe(III) as ferric citrate is added to anaerobic culture of K. oxytoca BAS‐10, in the presence of palladium species, to increase the EPS secretion and improve Pd‐EPS yield. In this process, bi‐metallic (FePd‐EPS) biomaterials were produced for the first time. The morphology of bi‐metallic EPS, and the chemical state of the two metals in the FePd‐EPS, are investigated by transmission electron microscopy, Fourier transform infra‐red spectroscopy, micro‐X‐ray fluorescence, and X‐ray absorption spectroscopy methods (XANES and EXAFS), and compared with mono‐metallic Pd‐EPS and Fe‐EPS complexes. Iron in FePd‐EPS is in the mineralized form of iron oxides/hydroxides, predominantly in the form of Fe3+, with a small amount of Fe2+ in the structure, most probably a mixture of different nano‐crystalline iron oxides and hydroxides, as in mono‐metallic Fe‐EPS. Palladium is found as Pd(0) in the form of metallic nanoparticles with face‐centred cubic structure in both bi‐metallic (FePd‐EPS) and mono‐metallic (Pd‐EPS) species. In bi‐metallic species, Pd and Fe nanoparticles agglomerate in larger clusters, but they remain spatially separated. The catalytic ability of bi‐metallic species (FePd‐EPS) in a hydrodechlorination reaction is improved in comparison with mono‐metallic Pd‐EPS.  相似文献   

16.
The Fe14.5Co16.5Ni55B15 and the Fe13Co15.5Ni51.5B20 ferromagnetic nanowires were deposited using the electrochemical deposition method. The structure of these nanowires was investigated using X-ray diffraction. Squid magnetometer was used to investigate the magnetic behavior. The hysteresis loops of 50 μm long nanowire arrays were studied as a function of boron concentration, nanowire diameter and field orientation. The competition between shape anisotropy and magnetostatic interactions played a vital role in determining the magnetic field necessary to saturate an array. The decrease in coercive field (Hc) and the squareness (SQ) of the hysteresis loop from 100 to 200 nm wire diameter for both types of compositions suggests the formation of multidomains in the nanowire.  相似文献   

17.
Fe1-x Co x nanowires are obtained by electrochemical deposition into the pores of track-etched membranes. The characteristics of the growth process that allow controlling the length and aspect ratio of the nanowires are established. The elemental composition and magnetic properties of the nanowires depend on the diameter of the track-etched pores, which varies from 30 to 200 nm, and the electrochemical potential U (650–850 mV), which determines the nanowire growth rate. According to the results of elemental analysis and the Mössbauer spectroscopy data, the Co content in Fe1-x Co x lies in the range of x=0.20?0.25. It is found that the orientation of the magnetic moment of Fe–Co nanoparticles in the wires depends both on the track pore size d and on the nanowire growth rate. Thus, the magnetic moments in nanowires grown in 50-nm-diameter pores are oriented within 0°–40° with respect to the nanowire axis. The magnetic properties of the nanowires are explained in the framework of a theoretical model describing the magnetic dynamics of nanocomposites, which was extended to include the relaxation of the magnetization vector and to take into account interaction between the particles. The key physical parameters important for the technological applications of the nanowires are determined, their dependence on the nanowire growth conditions is traced, and the possibility of controlling them is established.  相似文献   

18.
The phase composition, crystal structure, and magnetic properties of films of the ordered alloys FePd, FePt, and Fe50Pd50 − x Pt x , where x = 1–10 at %, were analyzed. The spectral dependences of the magnetic rotation and optical absorption were taken. The effect of heat treatment on the crystal structure, magnetization, and coercive field strength of the ordered alloy films was studied. The influence of the degree of atomic ordering on the perpendicular magnetic anisotropy was investigated. It was shown that films of ordered FePd and FePt alloys of equiatomic composition and films of Fe50Pd50 − x Pt x , where x = 1–10 at %, can serve as media for magnetic and thermomagnetic data recording and storage.  相似文献   

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