Jianjun Han

Surface Passivation of CdSe Quantum Dots in All Inorganic Amorphous Solid by Forming Cd 1−x Zn x Se Shell

CdSe quantum dots (QDs) doped glasses have been widely investigated for optical filters, LED color converter and other optical emitters. Unlike CdSe QDs in solution, it is difficult to passivate the surface defects of CdSe QDs in glass matrix, which strongly suppress its intrinsic emission. In this study, surface passivation of CdSe quantum dots (QDs) by Cd1−xZnxSe shell in silicate glass was reported. An increase in the Se/Cd ratio can lead to the partial passivation of the surface states and appearance of the intrinsic emission of CdSe QDs. Optimizing the heat-treatment condition promotes the incorporation of Zn into CdSe QDs and results in the quenching of the defect emission. Formation of CdSe/Cd1−xZnxSe core/graded shell QDs is evidenced by the experimental results of TEM and Raman spectroscopy. Realization of the surface passivation and intrinsic emission of II-VI QDs may facilitate the wide applications of QDs doped all inorganic amorphous materials.

Formation of core/shell PbS/Na 2 SrSi 2 O 6 nanocrystals in glass

In this work, PbS QDs were precipitated in the glass containing sodium strontium silicate (Na2SrSi2O6) nanocrystals. Tunable absorption and photoluminescence of PbS QDs in the range of 1700-2200 nm were achieved through thermal treatment. Increased heat-treatment duration and temperature would induce the formation of Na2SrSi2O6 nanocrystals. The results from absorption and photoluminescence spectra and X-ray diffraction patterns indicated that PbS QDs acted as nucleating agents for Na2SrSi2O6 nanocrystals and facilitate their formation. The high resolution transmission electron microscopy analysis confirmed that PbS/Na2SrSi2O6 core/shell nanocrystals were formed in the glasses.

Corrosion mechanism of E-glass of chemical resistance glass fiber in acid environment

The corrosion of ECR glass fiber was investigated by the analysis methods of weight loss ratio under different acids and at various durations. Weight loss, leaching of cations, and surface composition of ECR glass fiber were analyzed. The corrosion mechanism of ECR glass fiber in acid environment was also discussed. The experimental results showed that the corrosion degree of ECR glass fiber in different acids obeyed the order: HNO3>H2SO4>HCl. The acid effects on corrosion of ECR glass fiberis were totally different. Hydrochloric acid mainly destroyed the network structure of [AlO4], while sulfuric acid and nitric acid mainly destroyed the structure of [SiO4]. The acid resistance of ECR glass fiber is much better than that of E glass fiber due to the generation of intermediate product silicic acid gel Si(OH)4 during ion exchange. It can adhere to the glass surface to form a thin film and hinder the proceeding of corrosion.

Melting properties of loose and granulated glass batch

The physical properties, the pre-reacting performance and melting properties of the loose glass batch and the granulated glass batch were investigated, respectively. The experimental results showed that compacted glass batch could reduce dust, use ultra-fine powder, and improve heat transfer efficiency. When loose glass batch was compressed into granular, the thermal conductivity was increased from 0.273 W/m·°C to 0.430 W/m·°C, the activation energy Ea of pre-reacting decreased from 178.77 kJ/mol to 143.30 kJ/mol. Using the pre-reacted granular glass batch can significantly reduce the melting time, increase the batch melting rate, and decrease the heat consumption of 1kg molten glass from 3591.24 to 3277.03kJ/kg.

Effect of the Formation of CNTs on the Reduction of Ilmenite

The reduction process of ilmenite by hydrogen and methane under MPCVD was analyzed by XRD result. The reduction degree of ilmenite increased with adding methane, the case similar to reduction rate. The mechanism of reduction process changed with the increasement of methane flow because of the formation of carbon nanotubes (CNTs). The morphology of reduced samples was observed by SEM, and it was found that CNTs played an important role in the fracture of ilmenite particles. The reduction kinetics showed that the reduction was rate-controlling for hydrogen, and diffusion-controlling when hydrogen mixed with high flow methane.