纳米晶Sm_2Co_(17)型块体永磁的制备及磁性能

制备了两种2∶17R型Sm-Co合金:Sm2(Fe,Cu,Zr,Co)17和纯二元Sm2Co17,并利用高能球磨和放电等离子烧结(SPS)制备了致密的纳米晶块体合金,研究了其磁性能和相结构的变化。Sm2(Fe,Cu,Zr,Co)17具有较高的矫顽力,而纯二元Sm2Co17矫顽力基本为零。但高能球磨可快速降低Sm2(Fe,Cu,Zr,Co)17合金的矫顽力。利用放电等离子烧结非晶粉末制备了纳米晶块体合金,纯二元Sm2Co17合金具有较高的矫顽力,并且具有1∶7H相结构。而Sm2(Fe,Cu,Zr,Co)17合金则因为Fe-Co相及Sm2O3相的析出,具有较高的饱和磁化强度和极低的矫顽力。     

Fe77Co2Zr9B10Cu2合金的制备及其磁性能

采用单辊快淬法制备了Fe77Co2Zr9B10Cu2合金,在530～750℃等温退火40 min,利用X射线衍射和振动样品磁强计研究了Fe77 Co2 Zr9 B10 Cu2合金的微观结构和磁性能。结果表明:淬态Fe77Co2Zr9B10Cu2合金为非晶、纳米晶双相结构。随着退火温度的升高,α-Fe晶体相从非晶、基体中析出,晶粒尺寸长大,晶化体积分数增加,矫顽力先减小后增大,比饱和磁化强度逐渐增大。实验结果表明,530℃退火后合金的矫顽力最小,在670℃时迅速增大。样品的磁性与其微观结构、晶粒尺寸、晶化体积分数等因素有关.     

Sm(CO,Fe,Cu,Zr)z(6.5≤z≤8.5)高温永磁合金的组织结构与性能

介绍了Sm（Co,Fe,Cu,Zr）z永磁合金的显微组织结构特点以及热处理工艺参数对组织结构的影响,讨论了Sm含量及合金元素对微观组织与性能的影响规律,并对合金的矫顽力随温度的反常变化现象、矫顽力增强机理和热稳定性研究进行了总结和讨论．     

退火对玻璃包覆Fe_(69)Co_(10)Si_8B_(13)非晶微丝磁性能及力学性能的影响

研究了退火对玻璃包覆Fe69Co10Si8B13非晶合金微丝磁性能和力学性能的影响。结果表明,退火温度为450℃时,矫顽力和剩磁比最小,轴向和径向矫顽力分别为1.8Oe和8.5Oe,比退火前降低了31%和36%,轴向和径向剩磁比分别为0.031和0.012,比退火前降低了74%和63%。当退火温度低于450℃时,芯丝抗拉强度基本保持不变,平均抗拉强度约2500MPa;当退火温度高于450℃时,芯丝抗拉强度迅速降低。未退火及退火温度低于450℃退火时,合金芯丝断口存在少量的脉状花样,且脉状花样及花样交叉的数量越多,所对应的芯丝抗拉强度越高;经500℃以上退火后,放射状撕裂区占芯丝断口大部分面积,芯丝表现出更大的脆性。在450℃20min条件下退火,微丝具有较低的矫顽力和较高的强度,综合性能优良。     

(Fe50Co50)73.5Cu1Nb3Si13.5B9合金的微观结构及软磁性能

研究了(Fe50Co50)73.5Cu1Nb3Si13.5B9合金晶化过程中的微观结构及形成纳米晶后的合金软磁性能,发现在FINEMET合金基础上,用Co置换1/2含量Fe形成的(Fe50Co50)73.5Cu1Nb3Si13.5B9非晶合金具有相对较高居里温度Tc≈450℃,460℃退火处理后(Fe50Co50)73.5Cu1Nb3Si13.5B9合金形成均匀纳米晶组织,晶粒度约为20nm.     

Ag、Cu添加对Fe40Co40Zr6Mo4B10合金热稳定性和磁性能的影响

采用单辊快淬法制备Fe40Co40Zr6Mo4B10、Fe40Co40Zr6Mo4B9Ag1和Fe40Co40Zr6Mo4B9Cu1三种非晶合金,在不同温度下对3种合金进行热处理。利用DSC、XRD、VSM对合金的热性能、微观结构和磁性能进行测试。结果发现,Ag和Cu元素的添加均提高了合金的热稳定性,同时也降低了合金的矫顽力。Cu元素的添加作用更为明显。Fe40Co40Zr6Mo4B9Cu1合金具有相对高的热稳定性能和低的矫顽力。     

Fe0.3Co0.7纳米有序阵列的制备和磁性

使用小孔径阳极氧化铝模板制备Fe0.3Co0.7纳米线有序阵列,研究了热处理对其磁性的影响.结果表明,热处理对Fe0.3Co0.7纳米线有序阵列的结晶度和局部形状各向异性有重大的影响,导致纳米阵列的矫顽力和剩磁比发生相应的变化.在适当热处理条件下获得的Fe0.3Co0.7纳米线有序阵列具有较高的矫顽力和剩磁比.在H2保护下550℃处理时获得最高的矫顽力2.63×105 A/m,矫顽力随着热处理时间的增加先是快速增加,然后趋向平缓,最后有一定程度的下降.     

具有正温度系数的2:17型Sm(Co,Fe,Cu,Zr)z永磁体的研究现状

总结了矫顽力具有正温度系数的2:17型Sm(Co,Fe,Cu,Zr)z永磁体的研究现状;分析了成分与胞状显微组织对矫顽力正温度系数的影响,概括了目前解释矫顽力正温度系数的几种矫顽力机制模型,提出了对矫顽力正温度系数的研究是高温永磁体Sm(Co,Fe,Cu,Zr)z今后一个很有前景的新研究方向.     

退火温度对(Fe0.2Co0.8)76.9Cu0.6Nb2.5Si11B9软磁合金磁谱的影响

研究了退火温度对(Fe0.2Co0.8)76.9Cu0.6Nb2.5Si11B9纳米晶软磁合金磁谱(频率范围在100Hz～110MHz)的影响,进一步分析了退火温度与(Fe0.2Co0.8)76.9Cu0.6Nb2.5Si11B9纳米晶软磁合金初始磁导率、弛豫频率及品质数的关系.发现在673～873K范围内,退火温度只改变(Fe0.2Co0.8)76.9Cu0.6Nb2.5Si11B9纳米晶软磁合金磁谱中μ′-f曲线高低,而对磁谱曲线的形状几乎没有影响;当退火温度Ta=673K时,该合金在高频下有优良的软磁性能:μ′i(0.05A/m,1MHz)=420,弛豫频率f0=3.5MHz.     

磁场退火对纳米晶Fe_(74.5)Cu_1Nb_2Si_(17.5)B_5合金饱和磁致伸缩系数和μi-T曲线的影响研究

研究了不同退火温度下形成的纳米晶Fe_(74.5)Cu_1Nb_2Si_(17.5)B_5合金经过磁场退火后,其饱和磁致伸缩系数λ_S、矫顽力H_C和μi-T曲线的变化。研究表明,经过磁场退火后,纳米晶合金的矫顽力出现不同程度的降低,温度在350℃以下时,初始磁导率表现出明显的提高,这些性能的改善归因于合金饱和磁致伸缩的减小。     

Thermoelectric properties of nanocrystalline Ca(3-x)Cu(x)Co4O9 (0 < or = x < or = 0.32) for power generation

We successfully synthesized nano-sized Ca(3-x)Cu(x)Co4O9 (0 < or = x < or = 0.32) powders by solution combustion process. Plate-like grains and porous structure were observed in the sintered Ca(3-x)Cu(x)Co4O9 ceramics. The sintered Ca(3-x)Cu(x)Co4O9 showed a monoclinic symmetry. The electrical conductivity of the Ca(3-x)Cu(x)Co4O9 increased with increasing temperature, indicative of a semiconducting behavior. The added Cu led to a significant increase in the electrical conductivity. The Seebeck coefficient of the Cu-added Ca(3-x)Cu(x)Co4O9 was much higher than that of the Cu-free Ca3Co4O9. The highest power factor (9.99 x 10(-4) Wm(-1)K-2) was obtained for Ca2.76Cu0.24Co4O9 at 800 degrees C.     

Co nanoislands on Au(111) and Cu(111) surfaces studied by scanning tunneling microscopy and spectroscopy

Co nanoislands on the Au(111) and Cu(111) surfaces have been studied by scanning tunneling microscopy and spectroscopy. The experimental results showed that Co nanoislands prefer to aggregate at the step edge and dislocation sites on the reconstructed Au(111) surface and at the step edge on the Cu(111) surface, respectively. In addition, based on dZ/dV-V spectra, in both the Co/Au(111) and the Co/Cu(111) systems, Gundlach oscillation was observed. From the peak shift of dZ/dV-V spectra between Co nanoisland and substrate surface, we can quantitatively obtain that the constant energy separation is -0.13 +/- 0.01 eV for the Co/Au(111) system, and 0.41 +/- 0.02 eV for the Co/Cu(111) system, respectively. These values indicate the work function difference between Co nanoisland and these surfaces.     

Analytical electron microscopy of Sm(Co,Fe,Cu, Zr)9

Electron microscopic studies of as-cast Sm(Co,Fe,Cu,Zr)₉ magnets revealed a hexagonal phase of the type Sm₂(Co,Fe,Cu,Zr)₁₇ with crystal lattice parameters of a=0.84 nm and c=3.2 nm. After a solid solution treatment, only rhombohedral (3R) and hexagonal (2H) grains were found. After an additional annealing treatment at 800°C, grains with a microcellular precipitation structure similar to the one found in Sm(Co,Fe,Cu,Zr)_7.5 magnets occurred. In addition, in the as-cast and after-aged samples, other, partly unidentified Cu- or (Co,Fe)-enriched phases were detected     

Synthesis, characterization and structure effects on preconcentration and extraction of N,N'-bis-(salicylaldehydene)-1,4-bis-(p-aminophenoxy) butane towards some divalent cations

Separation with solvent extraction of Cu(II), Co(II) and Ni(II) from aqueous solution using N,N'-bis-(salicylaldehydene)-1,4-bis-(p-aminophenoxy)butane (H(2)L) as the new extractant has been studied. The new Schiff base, was synthesized by reaction of 1,4-bis-(p-aminophenoxy)butane and salicylaldehyde. Microanalytical data, elemental analysis, UV-vis (1)H NMR and (13)C NMR spectra and IR-spectra were used to confirm the structures. The extractability and selectivity of divalent cations was evaluated as a function of relationship between distribution ratios of the metal and pH or ligand concentration. Cu(+2) showed the highest extractability and selectivity at pH 7.8, whereas Ni(+2) and Co(+2) showed at pH 9.2. From the loaded organic phase, Cu(II), Co(II), Ni(II) stripping were carried out in one stage with aqueous acid solution including various concentrations of HCl. The stripping efficiency was found to be quantitative in case of 1.5M HCl. From quantitative evaluation of the extraction equilibrium data, it has been deduced that the complexes extracted are the simple 1:1 chelates, CuL, CoL, NiL.     

Large improvement of coercivity in Sm-(Co,Cu)/Fe films by Cu addition

The magnetic properties and microstructure of Sm-(Co,Cu)/Fe films were investigated systematically. The addition of Cu is helpful for keeping a better multilayer structure due to the reduction of the crystallization temperature of the hard phase. With lowering the temperature, the coercivity of the Sm-(Co,Cu)/Fe films increases rapidly with a linear relationship. The Cu addition significantly improves the coercivities of the Sm-(Co,Cu)/Fe multilayer films, especially at the low temperatures. Adding the Cu as well as lowering the temperature cause a large inhomogeneity in the hard phase, and therefore a high pinning coercivity.     

Giant Magnetoresistance Effect of [bcc-Fe(M)/Cu](M=Co,Ni) Multilayers

1. IlltroductionGiant magnetoresistance (GMR) effect of metallic multilayers has been widely investigated after thefinding by Baibich et al.11], as a new phenomenon tobreak through the memory density in ultra high density magnetic recording, high sensitivity in magnetichead, and so on. Metallic multilsyers of 3d transition elements could be classified into three groups of[bee/bcc], [fee/fccl and [bee/fcc] from the standpointof combination of crystal structure of constituting elements of metal…     

Properties of Co on Cu(111) revealed by AES and DEPES

Auger electron (AES) and directional elastic peak electron (DEPES) spectroscopies were used to investigate the Co/Cu(111) interface. The change in the Auger Cu (M_2,3VV transition at 66 eV) peak intensity (h_Cu) recorded at room temperature shows that the Co growth mechanism is not a layer by layer type. This proves that Co does not wet the Cu substrate. The recorded DEPES profiles reveal the coexistence of fcc and hcp Co structures already at an early stage of growth (0.8 ML). The Co coverage increase leads to the reduction of intensities associated with the fcc structure and significant increase of the signal from the hcp structure. The comparison between experimental and theoretical data at large coverages (43 ML) shows a major contribution of the hcp structure within the Co layers in the recorded DEPES profiles.     

Exchange of first row transition metal ions with n-butylamine intercalate of tin(IV) hydrogenphosphate

The exchange of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) on n-butylamine tin phosphate intercalate was achieved at 25°C by using metal ion acetate solutions. The uptake behaviour of Mn(II), Co(II) and Ni(II) is similar and there is a progressive decrease of the interlayer distance; while for Cu(II) and Zn(II), there is a gradual disappearance of the reflection which corresponds to the interlayer distance of the n-butylamine tin phosphate intercalate, and a new reflection appears, which correspond to the interlayer distance of the fully exchanged phase. All compounds were examined by diffuse reflectance spectroscopy, X-ray diffraction, magnetic susceptibility measurements ans DTA-TG. Manganese, cobalt and nickel compounds present an actahedral stereochemistry, while, the copper compound is octahedral with a tetragonal distortion. The probable stereochemistry of the anhydrous phases obtained by heating at 480°C is also given.     

Determination of copper(II) by displacement substoichiometric extraction with radiolabeled cobalt(II)

A substoichiometric radiochemical displacement technique has been employed for the quantification of trace amounts of copper from complex matrices. The procedure is based on higher stability of copper bipyridine complex compared to its cobalt analog, which leads to the displacement of spiked (⁶⁰Co) cobalt from its bipyridine complex in n-butanol by Cu(II). The amount of labeled cobalt stripped back into the aqueous phase is proportional to the amount of copper incorporated into the organic phase and is monitored for the quantitative estimation of copper. The interferences from various allied ions were critically examined. The proposed method has been successfully employed for the estimation of copper from various certified alloys.     

Cu部分代Co超细硬质合金研究

基于Cu与Co相同的晶型结构和相似的原子结构,采用共沉淀方法,制备Cu部分代Co的WC—10Co硬质合金,研究Cu对材料的组织和力学性能的影响。实验结果表明,通过Cu—Co共沉淀方式将cu加入粘接相中,形成Co（Cu）固溶体,在液相烧结过程中Cu均匀地分布在Co中,可以降低WC在粘接相中的溶解度,有效阻碍WC颗粒的溶解...