A series of (GdxDy1-x)Co2 (0-0.55) compounds have been prepared by arc-melting method. In order to determine the phase transition order in these compounds, we have performed some magnetization measurements. Only from the plots of temperature dependence of magnetization and the low-field magnetization isotherms, it is difficult to judge the phase transition order. The low-field Arrott plot is proved to be a more reliable method to characterize the first-order transition and the second-order transition. No first-order transition is observed in (GdxDy1 x)Co2 compounds (xa0). The result is discussed in the Inoue-Shimizu like model.

A simple hydrothermal route, using cetyltrimethylammonium bromide (CTAB) as the surfactant, has been proposed for synthesizing single-crystalline spinal cobalt ferrite (CoFe2O4) nanorods. Transmission electron microscope (TEM) and scanning electron microscopy (SEM) images indicated that the final product consists of nanorods with a diameter of about 25nm andlength up to about 120 nm.Furthermore, high-resolution TEM (HRTEM) revealeda clear lattice structure of the [1 0 0] planes in the nanorods. The magnetic properties of the CoFe2O4 nanorods were characterized using vibrating sample magnetometer (VSM). The possible formation mechanism for the CTAB-assistedhyd rothermal synthesis of CoFe2O4 nanorods has been discussed.

CoFe2O4 nanowire arrays with an average diameter of about 40 nm were prepared in porous anodic aluminum oxide (AAO) template using sol-gel process. Transmission electron microscopy (TEM) diffraction pattern and X-ray diffraction (XRD) showed that the nanowires were polycrystalline phase. Magnetic measurements showed the arrays of nanowires did not show a preferential magnetic orientation, the reason was briefly discussed. The effect of heating rate on the structure and magnetic properties of CoFe2O4 nanowire arrays was investigated. The result showed that the coercivity decreased with the increase of the heating rate.

Co-Pb nanowire arrays with an average diameter of 20nm and lengths up to several micrometers were grown in ordered anodic alumina templates using AC electrodeposition. The as-deposited samples were annealed at different temperatures. The structure and magnetic properties of Co-Pb nanowires were analyzed by X-ray diffraction and a vibrating sample magnetometer. We found that the sample annealed at 700℃ had large perpendicular coercivity Hc (as high as 2660 Oe) and high squareness (MR/Ms) (about 0.97), which was much larger than that of pure Co nanowires annealed at 700℃ (2170 Oe, 0.9). The change in coercivity and squareness associated with the microstructure was discussed.

We have succeeded in synthesizing PrFe11V12xTix (x50.2-1) compound and their nitrides with the ThMn12-type structure. The phase formation and magnetic properties have been investigated by x-ray diffraction, differential thermometric analysis, and magnetic measurement. The stable temperature range of the 1-12 phase for PrFe11V12xTix alloys has been determined as a function of Ti content. PrFe11V compounds with the ThMn12-type structure do not exist and PrFe11Ti compounds with the TnMn12-type structure are obtained by annealing in a narrow temperature range between 1303 and 1383 K. Furthermore, 1-12 phase with the ThMn12-type structure can be obtained at lower temperature and wider temperature range with decreasing Ti content x (0.2<x<1). PrFe11V12xTixNy with x50.2-1 has a Tc of about 730-785K, Ba larger than 8 T and Ms in the range 144-148 emu/g. These intrinsic magnetic properties are highly favorable for permanent magnet applications. As a preliminary, an intrinsic coercivity of 5.4 kOe is obtained for PrFe11V0.5Ti0.5Ny at room temperature by using mechanical alloying technique.

Pseudobinary Pr12xTbx(Fe0.6Co0.4)2 (0<x<0.4) cubic Laves single phases have been synthesized by melt spinning and subsequent annealing. Their structure, magnetic properties and stability have been investigated. The composition, at which the anisotropy of Pr12xTbx(Fe0.6Co0.4)2 is compensated, is close to x50.1. The spontaneous magnetostrictions l111 of Pr0.9Tb0.1(Fe0.6Co0.4)2 and Pr0.8Tb0.2(Fe0.6Co0.4)2 are larger than 150031026 and 190031026, respectively. Pr12xTbx(Fe0.6Co0.4)2 (0.1<x<0.4) ribbon-based materials with 3% epoxy resin combine high magnetostriction with significant magnetic coercivity. Pr0.9Tb0.1(Fe0.6Co0.4)2 is a promising magnetostrictive material.

Phase formation in annealed mechanical alloyed NdFe V Ti, and magnetic properties of the consequent phases and their 10.51+x1.5 (1-x)Tix nitrides were investigated by using X-ray diffraction and magnetic measurement. From the X-ray diffraction patterns we have constructed a phase formation diagram as a function of Ti content x and annealing temperature. The demarcation curve between 1:7 and 1:12 phases moves to higher annealing temperatures with increasing Ti content. In the NdFe Ti alloy the ThMn structure is obtained by annealing 11:12 the as-milled powder at temperatures above 950℃. The nitrides NdFe V Ti N retain the same structure as their parent 10.5+0.5xV1.5 (1+x) compounds. The nitride with high V content is more stable than that with low V content. Upon nitrogenation, the Curie temperature is enhanced from 150℃ to 180℃. In NdFe V Ti N T the values fall in the range 450～480℃. The hard magnetic properties 10.5+0.5xV1.5 (1-x)TixNy magnets have been assessed.

A nonequilibrium phase transformation in a stoichiometric NdFe11Ti compound during mechanical milling was monitored by the measurements of AC susceptibility, magnetization, X-ray di

A simple two-step hydrogen reduction method was used to synthesize FePt/Fe composite nanotubes. As the first step, L10 FePt nanotubes were prepared by heating a porous alumina template loaded with an alcohol solution of a Fe chloride and Pt chloride mixture in flowing hydrogen at 670℃. Then, FePt/Fe composite nanotubes were obtained by reducing the alcohol solution of the Fe chloride within the formed FePt nanotubes at a lower temperature, namely 470℃. Through changing the concentrations of initial alcohol solutions, the FePt:Fe atomic ratios of the composite nanotubes were easily adjusted and the magnetic properties were tuned accordingly. For (FePt)100−x /Fex composite nanotubes with x ranging between 0 and 26 at.%, the hard and soft phases were well coupled and the coercivity was tunable over a large range (1.27-2.73 T). Furthermore, the marked interdiffusion between Fe and FePt, which usually exists in FePt-based composites fabricated by using conventional methods, was not observed in the formed composite nanotubes. This indicates the two-step hydrogen reduction method to be a promising route for synthesizing nanocomposites which are difficult to fabricate by using conventional methods due to the interdiffusion between different phase

20 nm diameter Fe-Co nanowire arrays with different composition were fabricated by electrodeposition. A nanoporous anodized aluminium oxide film was used as the substrate. The microstructure and magnetic properties were studied by x-ray fluorescence, transmission electron microscopy, x-ray diffraction and vibrating samplemagnetometry. Both the coercivity Hc and the spontaneous magnetization Ms increase when the Co content in Fe-Co alloy increases from 0 to about 30 at.%, and then decrease with further increase in the Co content. A model called the 'chain of crystals' is developed and solved to explain the experimental results.