Papers by Author: Wei Wei Ju

Abstract: Four kinds of three-dimensional structure of graphane are investigated using first-principles method. It is found that the energy of four different structures has little difference, so the conclusion can be drawn that the four structures are likely to exist synchronously in experiments.

Abstract: Performing ab-initio total-energy calculations to investigate the adsorption and diffusion processes of the Au atoms with both the clean Si(001)-(1×1) and H-terminated Si(001)-(2×1) surfaces. It was found that, on the clean Si(001)-(1×1) surface, the most stable adsorption sites for Au atoms are middle part of four Si atoms, while on H-terminated Si(001)-(2×1) surface, the most stable sites are the middle part of a Si-Si dimer. The result showed that surface hydrogenation make most stable site transfer and affect the adsorption of Au on Si(001) surface.

Abstract: The electrical properties of 10M2O-36Fe2O3-54P2O5 (M=Li, Na and K) glasses were studied in the temperature range from 323 to 573 K. Non-linear Arrhenius behavior was observed for all the samples examined. It was shown that in both high- and low-temperature ranges, the replacement of Li, Na and K would result in decreases in both the dc conductivity and the activation energy. Analysis of the relationship of the parameters included in the Arrhenius equation, activation energy and the pre- exponential factor for each sample, preliminary explanations for these experimental phenomena have been presented.

Abstract: CaCu3Ti4O12 and CaCu3Ti3.9Zr0.1O12 ceramics were prepared by the traditional solid-state reaction method and the dielectric properties were investigated. Comparison of the results of the two samples examined indicated that the partial replacement of titanium by zirconium in the system CaCu3Ti4O12 may result in different changes of the dielectric constant and dielectric loss. For these experimental phenomena possible explanations and predictions also have been presented.

Abstract: The adsorption of Au on clean Si(001) surface is investigated by the local density approximation using first-principles pseudopotentials. We found that the adsorption energy of Au on ideal Si(001)-(1×1) surface is lower than that on reconstructed Si(001)-(2×1) surface, suggesting that adsorbed Au atoms chemically react with the surface Si atoms and break Si-Si dimer bonds of the substrate. Furthermore, the intermixing of Au and Si is also considered and the calculation suggests that intermixing will not take place at low temperature. But due to the small energy barrier for Au atoms to diffuse into Si substrate, we can conclude that the Au-Si alloy is easily formed at relatively high temperature. This result should be one of the reasons of the lack of consensus on the issue of intermixing of Au and Si.