Fujie Liu

Effect of microstructure on the mechanical properties of PAN-based carbon fibers during high-temperature graphitization

The change of microstructure of PAN-based carbon fibers has been studied as a function of heat-treatment temperature (1,800–2,800 °C, stretching 0%) by Raman spectroscopy and X-ray diffraction. With increasing heat-treatment temperature, both the crystallite size (La, Lc) and the degree of preferred orientation (g) increase, while the crystallite interlayer spacing (d002) decreases. The values of both Rs and Rc decrease, while Rs decreases more quickly. It implies that the degrees of skin-core of the carbon fibers increase. The relationship between mechanical properties and microstructure of the variants is also explored in detail.

Effective energy transfer and luminescence of LB films based on europium-substituted heteropolytungstate

The europium-substituted heteropolytungstate K13Eu(SiW11O39)(2) was successfully assembled into two lipids by LB technique for the first time. X-ray diffraction has shown a well defined lamellar for the LB films. The LB films have been characterized by fluorescence spectra and the characteristic luminescence behaviors were discussed. The ligand-metal charge transfer band could be observed in the spectra of the LB films, which could not be found in that of heteropolytungstate solid. The results of fluorescence spectra indicate the energy could be effectively transferred from ligands to the Eu3+ ions in the LB films and the luminescence efficiency was increased greatly. The influences of various lipids on the luminescence of polyoxometalates were investigated. The various interactions between monolayer and polyanions have different effect on the luminescence properties of europium-substituted heteropolytungstate.