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.