[en] The diffusion reaction kinetics of weathered crust elution-deposited rare earth with mixed ammonium salts was studied. The influence of concentration of reagents and particle size of ore on diffusion rate was investigated. The results showed that the diffusion process and diffusion rate could be improved by increasing reagents concentration and decreasing diffusion flowing rate and particle size. The diffusion process could be explained with the shrinking core Model, which could be controlled by the diffusion rate of reacting reagents in porous solid layer.

[en] Si(1 1 1) was implanted by copper ions with different doses and copper distribution in silicon matrix was obtained. The as-implanted samples were annealed at 300 and 540 deg. C, respectively. Formation of copper silicides in as-implanted and annealed samples were studied. Thermodynamics and kinetics of the reaction were found to be different from reaction at copper-silicon interface that was applied in conventional studies of copper-silicon interaction. The defects in silicon induced by implantation and formation of copper silicides were recognized by Si(2 2 2) X-ray diffraction (XRD)

[en] Cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) coated on small particle silica gel was prepared. Direct enantiomeric resolution of six novel chiral tetrahedrone-type clusters has firstly been achieved on this CDMPC chiral stationary phase (CSP), using hexane as the mobile phase with various alcohols as modifiers. The influence of the mobile phase composition on the enantioselectivity was discussed, and the effect of structural variation of the solutes on their enantioseparation was also investigated and compared. It was found that both the metal in the tetrahedral core and the ligand coordinated to the atom in tetrahedral core had significant effects on their chromatographic behaviors

[en] A computer program to calculate atomic concentrations in the surface layer of multi-element solids from experimental RBS spectra is presented. The basic features of the computational model, its function and application scope are discussed in detail. The analysed sample is modeled as a series of layers each with the same thickness and the calculations proceed layer by layer from the surface, so that the concentration and the depth profile of each element can be obtained. The program is in BASIC and it is operated on the IBM microcomputer in the manner of man-computer conversation. A few of simple but quite reliable routines are available

[en] Tantalum carbide thin films were synthesized by ion beam enhanced deposition at room-temperature. Tantalum and graphite targets were alternatively sputtered by Ar⁺ with the energy of 1.5 KeV and the co-sputtered thin films were simultaneously bombarded by 15 KeV Ar⁺. The arrival ratios of Ta and C atoms could be conveniently controlled by adjusting the time of sputtering of targets. AES showed that thin films were dependent on the arrival ratios of Ta and C atoms. In combination with X-ray diffraction, it was found that TaC, Ta₂C and mixed phases of TaC and Ta₂C could be controlled by varying the arrival ratios of Ta and C atoms. Knoop's hardness measurement showed that the hardness of TaC was about 1500 kg/mm². (author). 13 refs.; 5 figs.; 1 tab

[en] Transition metal carbide thin films were synthesized by dual ion beam deposition. Metal (Ta, W, Mo) and graphite targets were alternately sputtered by Ar⁺ with an energy of 1.5 keV from a broad-beam Kaufman ion source. The resulting films were simultaneously bombarded by 15 keV Ar⁺ from another Kaufman ion source. The arrival ratios of metal and C atoms can be conveniently controlled by adjusting the relative time of sputtering. It was observed that different phases of carbides formed at different arrival ratios. All depositions were at room temperature. XPS showed the existence of free carbon atoms even for Me/C ratios >1. The effect of bombardment by Ar⁺ on the phase formation was also investigated. (orig.)

[en] A Monte Carlo simulation study of radiation damage produced by energetic electrons during their slowing down in solid is presented. The elastic and inelastic energy losses of the electron are followed through a succession of collisions until its energy degrades to a limiting value Emin. At any collision, the moving electron may transfer sufficient energy to a lattice atom to produce a displaced atom and a vacancy. A large number of incident electrons are followed and the locations of defects created are recorded in order to give the spatial distribution of the radiation damage in solids. The simulation results show that the concentration distribution of the defects with the depth in materials is not uniform. The damage level at the surface layer of the sample is higher than that obtained by using displacement cross-section. This simulation program can be used to estimate more accurately the displacement per atom, dpa. (author)

[en] The structural and magnetic properties of the ion-beam sputtered Fe/Mo multilayers were studied. The samples were prepared by keeping d_Mo at 40 A and varying d_Fe from 10 A to 60 A. The modulation wave-length and the film structures were determined by X-ray diffraction. The magnetic properties were measured with the vibrating sample magnetometer (VSM). The crystal orientation of the Fe/Mo multilayers with the Fe layer thickness d_Fe larger than 25 A were Fe(110)/Mo(110). The easy magnetization direction of the multilayers was parallel to the film plane, with the coercivity Hc maintained about 100 Oe over the range from d_Fe=10 A to d_Fe=60 A. The saturation magnetization of the Fe/Mo multilayers, 4πMs, reached 1.83 T for d_Fe=60 A and then dropped to 1.04 T for d_Fe=10 A. In the direction normal to the film plane, 4πMs was much lower, but Hc reaches up to 450 Oe for d_Fe=20 A. (author). 9 refs.; 5 figs

[en] Good intermixing between deposited Mo and an Fe substrate can be obtained by dynamic recoil mixing. The range of mixing zone increases monotonously as the dose rate and the temperature of the sample increase and has a saturation tendency with the increase of dose but is independent of the irradiation energy over 50 keV. In addition, the iron atoms in the substrate will be extended to the surface as the dose rate increases to over 50 μA cm^-2 under our experimental conditions. (author)

[en] Highlights: • First-time growth of Cu-filled carbon nanotube (Cu@VACNT) without extra catalysts. • Subtle evolution on the Cu substrate was vital for synthesizing Cu@VACNTs • Tuning the growth temperature controls the filling of Cu inside the VACNTs. • Superior field emission performance of Cu@VACNT core-shell field emitters. A highly conductive metal core modifies the electronic properties of a carbon shell, offering the possibility of enhancing its field emission (FE) behavior. Herein, a method has been devised to synthesize copper-filled vertically aligned carbon nanotubes (Cu@VACNTs) directly on Cu disks without extra metal catalysts via plasma-enhanced chemical vapor deposition. An ensemble of Cu particles formed on the surface of Cu disks due to surface reconstruction in a reducing environment plays a crucial role in the nucleation and growth of Cu@VACNTs. The filling of Cu inside the VACNTs can be controlled by tuning the growth temperature. The study of FE properties revealed that a conductive Cu-core extending throughout the entire length of the VACNTs could significantly enhance the FE properties of the VACNTs. Excellent FE properties including low turn-on field (E_To = 1.57 V/µm), low threshold field (E_Th = 2.43 V/µm), high field enhancement factor (β = 3061), and high FE stability were observed for the Cu@VACNTs. The enhanced FE properties of the Cu@VACNTs can be accredited to low field screening due to bundled morphology and improved electrical and thermal conductivities offered by the encapsulation of highly conductive Cu nanowires inside the cores of VACNTs.