Synthesis,Crystal Structure and Fluorescent Properties of Silver and Cadmium Complexes

Two new complexes [Ag（bix）]n·n NAA·n H2O（1） and [Cd（NAA）（phen）2（H2O）]2· 2CH3COO-·H2O（2）（bix = 1,4-bis（imidazol-1-ylmethyl）benzene,HNAA = α-naphthylacetic acid,phen = 1,10-phenanthroline） have been successfully synthesized under hydrothermal conditions.Their structures have been determined by elemental analyses,IR spectroscopy,TG and single-crystal X-ray diffraction analysis.The intermolecular hydrogen bonding or π-π stacking interactions extend the complexes into a 3D supramolecular structure.Moreover,the luminescent properties of complex 2 have been investigated in the solid state.

The microstructure of a single crystal superalloy after different aging heat treatments

To study the influence of aging heat treatments on the microstructure of single crystal superalloys with high content of refractory elements and optimal the aging heat treatment regimes, a single crystal superalloy containing 22 wt% refractory elements was investigated.Results show that for the experimental alloy, even the homogenization-solution heat treatment for 25 h cannot homogenize the alloying elements completely. During primary aging heat treatment, γ＇ phase grows larger and turns to regular cubes. Higher aging temperature induces larger γ＇ cubes. For specimens with primary aging heat treated at 1120 ℃,γ＇ morphology does not change apparently during secondary aging heat treatment. For specimens with primary aging heat treatment at 1150 ℃,γ＇phase in interdendrite grows obviously comparing with that in dendrites. By analyzing the precipitating kinetics of γ＇phase, it is found that owning to the dendrite segregation and different aging heat treatment temperatures, γ＇ phase at different regions grows under the control of different factors at different aging heat treatment stages. The two controlling factors that are driving forces of phase transformation and element diffusion rate induce obviously different growth rates of γ＇ phase. As a result, the γ＇-precipitating behaviors are variable based on different solute concentrations and aging temperatures. For advanced single crystal superalloys that are supposed to be used at relatively high temperatures, the final γ＇ size after aging heat treatment is suggested to be close to the crossing point of diffusion controlling curve and driving force controlling curve corresponding to the serving temperature. And then,high-temperature properties can be improved.

Effects of Nanosilica on Crystallization and Thermal Ageing Behaviors of Polyethylene Terephthalate

The effects of nanosilica（SiO2） on crystallization and thermal aging behaviors of polyethylene terephthalate（PET） have been studied using differential scanning calorimetry（DSC） and polarized optical microscopy（POM）, viscometry, tensile testing and scanning electron microscopy（SEM）. For non-isothermal and isothermal crystallizations, the crystallization rate of PET increases considerably with increasing content of SiO2 providing a large number of nucleation sites, but the relative crystallinity of the nanocomposites has little differences with that of neat PET. According to POM observation, the nucleation of PET becomes faster and the nucleation density increases significantly with increasing SiO2 content. For PET and its nanocomposites thermally aged at 190 ℃, the results of intrinsic viscosity, carboxyl content and tensile test show that the degradation rate of PET is reduced with the addition of a small content of SiO2, but the degradation rate increases with further addition of SiO2, owing to the dual effect of SiO2 on PET degradation.

Crystals based on solid solution of Ag_(1-x) Tl_xBr_(1-x) I_x for the manufacturing of IR fibers

For the development of fiber optics for the range from 0.2 to 50.0 μm, one needs light-stable, nonhygroscopic, ductile crystals that would be transparent within this spectral range and have a lack of cleavage, and from which the flexible infrared （IR） fibers are extruded. The crystals based on solid solutions of silver and monadic thallium haides meet the conditions listed above. Consequently, by differential thermal and x ray analyses, we study the TIBr-TII phase diagram using the crystals with optimal compositions, which we grow ourselves. We also manu- facture light-stable nanocrystalline IR fibers that are transparent at longer wavelengths compared with AgC1-AgBr fibers.