Diamond films have been deposited on AlN substrates using hot filament chemical vapor deposition. By applying a negative bias voltage, a high diamond nucleation density on AlN substrates as high as 10 10 cm-2 has been realized. The appearance of bias current and plasma induced on the AlN surface was found critical for the enhancement of diamond nucleation density. Satisfactory adhesion of the deposited diamond films with the AlN substrates has been achieved for application purposes. q2000 Elsevier Science B.V. All rights reserved.

The functionalization of carbon nanotubes (CNTs) was carried out by using different chemical treatment methods. These functionalized CNTs were characterized by TEM image and FT-IR spectra. The CNT electrodes are measured by thermal resistivity and cyclic voltammetry experiments. The results showed that two important factors controlled the electrochemical properties of the CNT film electrode: one is the active functional group; another is activation energy of the CNT film. From our experiments, we have found the electrode of 10min nitric acid treated CNTs have the optimal peaks in relation to carboxylic acids, the highest redox peak currents, the biggest value of k0 and welldefined quasi-reversible voltammograms for redox of iron couples, in which the two factors best match.

The magnetoresistance effect of p-type diamond films has been investigated at different temperature. Diamond films were grown by microwave plasma chemical vapor deposition. Mirror-polished p-type Si(100). was used as a substrate material. The experimental results show that a notable magnetoresistance effect in polycrystalline and heteroepitaxial semiconducting diamond films was observed. The relative changes in the resistivity of the diamond films with magnetic field strongly depended on both boron-doped concentration in the films and geometric form of the samples. The effect of disk structure was greater than that of strip-type samples, also variation in the resistivity of heteroepitaxial diamond films was greater than that of polycrystalline diamond films at same magnetic field. The magnetoresistance of p-type diamond films was decreased with increasing both boron-doped concentration and temperature. The relative changes in resistance of the heteroepitaxial diamond films with the disk structure was increased by 0.85 at room temperature under magnetic intensity of 5T, but only 0.40 for strip-type structure. The results are discussed in detail.

The Pr55-xAl12+xFe33−yCuy (0≤x≤5, 0≤y≤8) bulk metallic glasses (BMGs) 5mm in diameter and 100 mm in length were prepared by copper mold suction casting. Hysteresis loops of the Pr55−xAl12+xFe33−yCuy BMGs and the corresponding Pr55Al12Fe30Cu3 crystallized alloy were measured, and the results showed that the Pr55−xAl12+xFe33−yCuy BMGs are hard magnetic, while the completely crystallized Pr55Al12Fe30Cu3 alloy is paramagnetic at room temperature. The thermal behavior and crystallization of the Pr55Al12Fe30Cu3 BMG were studied by differential scanning calorimetry, and the results indicated that the Pr-based BMG has obvious glass transition and a wide supercooled liquid region up to 75K. The crystallization activation energy for the Pr55Al12Fe30Cu3 BMG is much smaller than that of Zr-Ti-Cu-Ni-Be BMG.

The process of diamond nucleation by hot filament chemical vapor deposition was investigated by atomic force microscopy. It was observed that a large number of micro-defects (pits) were produced on the surface of the silicon substrate due to ion bombardment under the negative potential and diamond nucleated on the pits. The formation of the pits and their role in diamond nucleation were theoretically approached. The results indicate that the number of the pits increased with increasing potential, the diamond nucleation density and the nucleation rate were functions of the pits, and they were in agreement with the experiment results.