Zhang Shuyuan

Hydrothermal preparation of long nanowires of vanadium oxide

Long beltlike nanowires were successfully synthesized for a semiconducting oxide of vanadium by a hydrothermal route at 180 °C for 5 h and were characterized by x-ray powder diffraction, energy dispersive x-ray spectroscopy, and electron diffraction microscopy. The product is mainly layered V 2 O 5 . 0.3H 2 O with a small fraction of V 2 O 5 . xH 2 O (0.3 < x < 1.7) and V 2 O 5 phases. The obtained nanowires, several tens of micrometers long and a few of tens of nanometers wide, are crystallized well, growing along the [010] direction. The effects of preparation conditions on the formation of the nanowires are discussed.

Preparation and electron spin resonance effect of nanometer-sized Mn2O3

Abstract Nanometer-sized manganic oxide (Mn 2 O 3 ) has been prepared for the first time by a chemical liquid homogeneous precipitation (CLHP) method. Transmission electron micrographs and X-ray powder diffraction patterns show that the average particle sizes are in the range of 9–50 nm. From the electron spin resonance (ESR) patterns of 9 nm manganic oxide particle, we can observe hyperfine structure (Six absorption peaks of ESR) of Mn 2+ ion adding the Mn 3+ ion signal.

Fractal formation and tunnelling effects on the conductivity of Au/a-Ge bilayer films

The fractal crystallization of the Au/a-Ge bilayer films has been investigated, and the resistance characteristics have been first measured by the two-probe configuration method. The experimental results suggest that the resistance R of various annealing films are influenced by the fractal formation and the fractal dimension. These phenomena were explained by the Random Tunnelling Junction Network (RTJN) model.

Effect of fractal crystallization on the depositing sequence of a Pd/Ge thin film system

The behavior of fractal crystallization in a Pd/Ge thin film system of various ratios of thickness (or composition) after annealing has been investigated by transmission electron microscope. It is difficult for coevaporated Pd–Ge films to obtain fractal crystallization. The fractal structure in Pd/a-Ge bilayer films can form more easily than in a-Ge/Pd bilayer films. The fractal crystallization was restricted because of the formation of the compounds (Pd2Ge and PdGe) in the Pd/Ge thin film system. Growth of the fractal structure depends on the competition between the two processes of amorphous germanium (a-Ge) crystallization and compound formation. Fractal formation can be explained by a random successive nucleation model.

A high-resolution electron microscopy study of microstructure of ZnS powder phosphors with different dopants

Abstract The microstructures of ZnS phosphors with different dopants and different luminescence mechanisms have been investigated by transmission electron microscopy (TEM). Our observations show that there are evident differences in the microstructures of ZnS: Fe, ZnS: Cu and ZnS: Mn. It is reasonable to infer from the TEM experiments that the photoluminescence probably relates mainly to the various stacking faults and dislocations, whereas the a.c. electroluminescence may have a relationship with the microtwin structure, and the coherent growth state of α- and β-phases may be the reason for the d.c. electroluminescence.

A TEM study of phases in the superconducting Y(Yb)-Ba-Cu-O system

Abstract The structure and compositions of phases in the superconducting Y(Yb)-Ba-Cu-O systems with three nominal compositions have been investigated in a transmission microscope (TEM). Based on our improved quantitative microanalysis method, more accurate contents of Y, Yb, Ba and Cu in phases have been obtained simultaneously with the structure determination by electron diffraction. There is no Ba in Y 2 Cu 2 O 5 phase and a little amount of Ba in (Y, Yb) 2 Cu 2 O 5 phase. The more Y 1 Ba 2 Cu 3 O 7 , the better the superconducting property.

New metastable phases in a Pd/amorphous Si bilayer after annealing

Abstract Two new metastable phases have been observed by means of transmission electron microscopy in a Pd/amorphous Si bilayer after annealing at 185 °C. One phase (NSA) is of a b.c.t. structure with a = 0.390 nm and c = 0.540 nm, and the other phase (NSB) is of two-dimensional hexagonal structure with a = 0.521 nm, whose reciprocal lattice points become continuous spikes in the c∗ direction of the reciprocal lattice.

Crystallization and Fractal Formation in Annealed Al/a-Ge Bilayer Films

The crystallization and fractal formation in annealed Al/a-Ge bilayer films were studied. It was found that the effect of metal-mediated crystallization increases with increasing annealing temperature and time. However, fractal patterns could be formed only in samples with proper thickness ratio. Some special phenomena at strain, broken, and step areas are also reported.

In Situ Plane-View and Cross-Sectional Transmission Electron Microscopy of Fractal Formation in Au/a-Ge Bilayer Films

Fractal crystallization in Au/a-Ge bilayer films has been studied by in situ plane-view and cross-sectional transmission electron microscopy. The experimental evidence suggests that the fractal crystallization is controlled by both diffusion and reaction processes. The growth kinetics analysis indicates that both diffusion-limited aggregation and random successive nucleation mechanisms play an important role in fractal crystallization in Au/a-Ge bilayer films.

Study on the cathode deposit produced in the process of carbon arc discharge

The cathode deposit produced by carbon arc discharge was studied by scanning electron microscopy, high resolution electron microscopy, x-ray diffraction and Raman spectroscopy. The results indicate that the stacking of hexagonal carbon layer in the discharged graphite is different from the ABAB stacking sequence in graphite, and that carbon nanotube is a kind of graphite-like micro-crystal with a low-dimensional structure.