Papers by Author: Ying Bang Yao

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Authors: Yi He Zhang, Qing Song Su, Li Yu, Li Bing Liao, Hong Zheng, Hai Tao Huang, Guo Ge Zhang, Ying Bang Yao, Cindy Lau, Helen Lai Wah Chan
Abstract: Phlogopite with layered silicate structure had been firstly chemically modified via an in situ intercalation method, and phlogopite-polymer nanocomposite films were prepared from 2,2'-bis (3,4-dicarboxyphenyl) hexafluropropane dianhydride (6FDA) and oxydimethyl aniline (ODA) in N,N-dimethylacetamide as a solvent by using in-situ polymerization process combined with ultrasonic dispersion and multi-step curing. The structure of phlogopite minerals and its polymer nanocomposites were characterized by X-ray diffraction (XRD) and infrared spectra (FTIR) respectively. The experimental results indicated that the phlogopites with layered nanostructure had lost their ordered structure and had been exfoliated or intercalated. Thereafter, they were dispersed randomly in the polyimide matrix. The dependence of dielectric properties and thermal stabilities of the nanocomposite films on the phlogopite content and frequency were studied.
Authors: Yi He Zhang, Qing Song Su, Li Yu, Hong Zheng, Hai Tao Huang, Guo Ge Zhang, Ying Bang Yao, Helen Lai Wah Chan
Abstract: A sol-gel process was used to prepare polyimide-silica hybrid films from the polyimide precursors and TEOS in N,N- dimethyl acetamide, then the hybrid film was treated with hydrofluoric acid to remove the dispersed silica particles, leaving pores with diameters between 80nm to 1µm, depending on the size of silica particles. The structure and dielectric constant of the hybrid and porous films were characterized by FTIR,SEM. The porous films displayed relatively low dielectric constant compared to the hybrid polyimide-silica films.
Authors: Yan Hua Fan, Shu Hui Yu, Rong Sun, Lei Li, Ru Xu Du, Yan Sheng Yin, Ying Bang Yao
Abstract: Ba0.7Sr0.3TiO3 thin films with a thickness of 300~900 nm were prepared with sol-gel method directly on the copper foils. The films have been processed in almost inert atmosphere such that the oxidation of Cu foil was avoided while allowing the film to crystallize. The crystal structure, morphology and dielectric properties of the films were measured and analyzed. The effects of annealing temperatures and film thickness on the electrical properties were discussed.
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