Papers by Author: Ying He

Abstract: GdSrCoO3-δ and Gd1-XSrXCoO3-δ (x=0.1~0.5) were synthesized using glycine-nitrate process (GNP). The formation process of perovskite phase and microstructure of powders were characterized using TG-DTA and XRD. All the powders with different doping amounts of Sr2+ on A-site were single-phase solid solutions, and the stable perovskite phase was formed completely after calcination at 1100°C. The crystal structures of the solid solutions transfer to a higher symmetrical perovskite.

Abstract: The cordierite powders have been synthesized by low temperature combustion technique using urea as fuel, nitrates as oxidizer and silicic acid as silica source. The sintering behavior and crystallization process were investigated. The results showed that the powders could be sintered at a temperature lower than 1000 °C. The μ-cordierite crystallized from glass at first, and then transformed into α-cordierite at higher temperature. The obtained cordierite based glass ceramics at different temperatures have low dielectric constant (4.16 ~ 5.02 at 1 MHz) and low dielectric dissipation factor (≈ 0.003 at 1 MHz) as well as low temperature sintering behavior, which is compatible for electronic packaging.

Abstract: In this paper, we have investigated the near-infrared luminescence emitting from NiSi2 passivated silicon nanocrystals (NCs) embedded in SiOx films. For comparison, we also prepared the regular specimen without NiSi2 passivation. In the both systems, the intensity of photoluminescence emission from NC-Si increased with the increase of annealing temperature, which was explained by the crystallization of amorphous silicon in SiOx films. The maximum intensity of near-infrared emission from NiSi2-passivated NC-Si was stronger by factor 5 than that of regular specimen without NiSi2 passivation. The model of NiSi2 passivation was employed to explain this phenomenon.

Abstract: In this paper, the effect of a thin interlayer of Pt on thermal stability of NiSi films on Si(111) has been studied. The Ni/Pt/Si(111) bilayered samples with the same film thickness were annealed by rapid thermal annealing at 640 °C-900 °C. Both the X-ray diffraction analysis and four-probe measurements show a remarkable improvement in the thermal stability NiSi as a result of Pt interlayer. The possible reason for the enhanced NiSi thermal stability is attributed to the formation of the Ni(Pt)Si solid solution and its preferred orientation, leading to the decrease in the driving force of NiSi2 nucleation and the increase in the interfacial energy change respectively. The experimental results are explained in terms of Miedema’s Model and Thomas-Fermi-Dirac (TFD) equations in detail.