Although rapidly solidified Nd–Fe–Al alloys exhibit hard magnetic properties they so far have not found any practical application, however, their study has great scientific meaning. Investigations of the Nd–Fe–Al alloys enable one to evaluate the effect of magnetic interactions, between nanoscale precipitates, having different structure and properties, on the macroscopically observed phenomena. The evolution of microstructure in the course of annealing is generally unclear. Most of the reported data were obtained for different materials, using various processing methods, which makes their comparison difficult. It was shown that different fabrication methods (melt spinning, suction casting) generate different properties. On the other hand, for the particular processing method the structure and magnetic properties are highly affected by the processing variables.
In this study the samples fabricated by two methods were compared. Melt spinning, with the roll speed 5–30 m/s, and casting into moulds having bore diameters 1, 3, 6 and 12 mm were used. The alloy composition was kept constant Nd60Fe30Al10. Strong dependence of the magnetic properties on quenching rate was proved. Application of the appropriate processing variables for both the methods (roll speed or rode diameter) enables one to obtain comparable quenching rates and thus overall similar magnetic properties. However, for the cylindrical specimens different cooling rates for the surface and core produces a structural gradient, which leads to variation of the magnetic properties on the sample cross-section. The structural and property gradients were evaluated using SEM and magnetic measurements, respectively. 相似文献
A basic understanding of the catalytic performance is needed to probe the physical properties that change with a reduction in the catalytic clusters size. It has been shown that the edge of low-width MoS2 nanoribbon has a metallic characteristic, while that of bulk MoS2 has a semi-conductive characteristic. For probing the observations, we constructed the models representing the surface atoms and the edge atoms of the MoS2 nanoribbon. The nanoribbon-like model can also be used to model the edge atoms of the nanocluster MoS2 .Then we calculated the density of states (DOS) of infinitely two-dimensional MoS2 and of the structure corresponding to the edge atoms of the MoS2 nanoribbon-like structure with Wien2K software. The magnetic moment of structures was calculated for identifying the magnetic structure. We found that the bulk MoS2 and infinitely two-dimensional MoS2 are semi-conductive and not magnetic, while the computation model corresponding to MoS2 nanoribbon is metallic. The calculation anticipates that the edges of the MoS2 nanocluster and the low-width MoS2 nanoribbon are strongly magnetic. 相似文献
Various poly(ε‐caprolactone)s (PCLs) prepared by ring‐opening polymerization of ε‐caprolactone (CL) initiated by a range of metallic derivatives such as alkoxides, Al(OiPr)3, La(OiPr)3, Sn(octanoate)2, Ti(OiPr)4, Zn[O(CH2)3NHtBoc]2, or borohydride La(BH4)3(THF)3 were evaluated for their in vitro cytotoxicity. The amount of residual metal present in the polymer samples was measured and compared to the initial quantity introduced. The effect of the metallic system on the biocompatibility profiles of the resulting polyesters was evaluated in vitro on PCL films from a series of cytotoxicity tests involving MTT and neutral red assays upon exposure to human osteoprogenitor cells. The absence of toxic influence of all these PCLs suggests that they may be used as biomaterials in contact with living human cells.
This paper will focus on the comparative study of the structural, electronic, magnetic, optical, and thermoelectric properties of the two Heusler systems Ag2TiGa and Ag2VGa in the inverse L21 Hg2CuTi structure. Using the density functional theory-based wien2k code, which implements the computational methods used in this study, namely GGA, GGA-mBJ, GGA + U, and GGA + SOC (spin-orbit coupling). The band structures show that all two structures studied are metallic. The spin density of states of Ag2VGa has evident spin splitting near the Fermi level , and the total magnetic moment of the Ag2VGa structure is 2.19 μB, which indicates that Ag2VGa is magnetic. The full-Heusler Ag2VGa material can be used as spintronic materials due to their high spin polarization (about 50%). While Ag2TiGa has low polarization so it is bad electronically, but better thermoelectrically than Ag2VGa. So, the full-Heusler Ag2TiGa material may also be considered as a potential candidate for thermoelectric applications at room temperature. Studies of the two new Heusler alloys may provide a theoretical reference for subsequent theoretical research and experimental synthesis of Ag-based Heusler alloys. 相似文献
