Papers by Author: Xiao Yang Gong

Abstract: Studies of ion motion in crystalline and glassy materials, Jonscher power law, which was frequently referred to as the so-called universal dynamic response (UDR) is an effective method, but the power law exponents obtained from curve-fitting are sensitively affected by the frequency window employed in the analysis. So how to choose frequency window and which window can truly describe the nature of the materials, are important for every researcher. In this paper, through analyzing the experimental data of frequency dependence of ac conductivity in 50Li₂O–50P₂O₅ glasses, a simple method to choose frequency window was found and further discussions indicated our choice was reasonable.

Abstract: A core-shell structure material, carbon fiber/MoS₂ was prepared by a surface modification precipitation process in aqueous solution. A nucleation model for this structure was proposed. Coating was obtained from 10-4M ammonium molybdate. The energy band gap of MoS₂ calculated from the absorption spectra was about 1.97eV. CFs/MoS₂ core-shell structure has strong absorption in the wavelength range from 400 to 1000nm, which is well fitted to visible light of the solar spectrum. The result of thermal analysis indicates that the composite is stable below 403 °C.

Abstract: A novel nano-iron particulate reinforced polymer-based composite material against electromagnetic pollution was prepared for household appliances. The attenuation, permittivity and various absorbing aspects of the composite materials were investigated. Results indicated that the composite materials exhibit promising effects of microwave absorption. The attenuation was affected by volume fraction of nano-iron powders. A single microwave absorption medium won’t be appreciable, and a combination of different microwave absorption materials is suggested.

Abstract: Based on Jonscher power law, frequency dependence of ac conductivity of 40Fe2O3–60P2O5 glasses were investigated in a relatively high temperature range. Results indicated the power law exponent first decreases with increasing temperature, reached a minimum at a certain temperature and then in- creases again. Preliminary theoretical explanations and predictions for this phenomenon were presented.

Abstract: CaCu3Ti4O12 ceramics were prepared by the traditional solid-state reaction method and the dielectric properties were investigated, the activation energy and relaxation time factor of the samples were calculated. Debye relaxation theory was attempted to analyze the experimental datum, the static and high-frequency dielectric constants were obtained according to Cole-Cole spectra. The temperature dependence of the dielectric constant of CaCu3Ti4O12 were fitted by computer and the theoretical results nearly agree with experimental results.

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.