Jing Cheng-bin

Microstructural probing of (1−x) GeS2−x Ga2S3 system glasses by Raman scattering

Raman scattering measurement of (1−x) GeS2−xGa2S3 system glasses was conducted in order to understand the microstructural change caused by the addition of Ga2S3. According to the change of Raman spectra with the addition of Ga2S3, two main structural transformations were deduced: the gradual enhancement of ethane-like structural units S3Ge−GeS3 (250 cm−1) and S3 Ga−GaS3 (270 cm−1) and the appearance of charge ambalanced units [Ga2S2(S1/2)4]2− and [Ga(S1/2)4]− And this change of structural aspect seems to give us a clue to understanding the cause of the increased rare-earth solubility.

Microstructure and thermal properties analysis of (1−x) As2S3−xCdBr2 glass system

The homogeneous glass sample for the (1−x)As2S3−xCdBr2, where x=0.015, 0.035, 0.05, was prepared by the conventional melt-quenched method. Amorphous (1−x)As2S3−xCdBr2 alloys were determined by X-ray diffraction, thermal comprehensive analysis and Raman scattering. The glass transition temperature (Tg) decreases a bit with the addition of CdBr2. Based on the experimental data, the microstructure is considered to be the discrete molecule species of AsBr3 and Cd−S atomic bonds or clusters are homogeneously dispersed in a disordered polymer network formed by AsS3 pyramids interlinked by sulfur bridges.

Microstructure and thermal properties of (1−x) As2S3−xCdCl2 glassy system

The homogenous glass samples of the (1−x) As2S3−xCdCl2 where x=0 and 0.05 were prepared by the conventional melt-quenched method. The addition of 5 mol% CdCl2 enhanced the glass transition temperature of pure As2S3 glass sample by about 30°C. Based on the experimental data, the microstructure is considered to be that the discrete molecule species of AsCl3 and nanocrystal CdS is homogeneously dispersed in the disordered polymer network formed by AsS3 pyramids interconnected by sulfur bridges.

IR spectra analysis of SiO2−TiO2−GeO2 gel glass of CO2 laser transmitting hollow waveguide

Both titanium and germanium were introduced into silicon dioxide system by sol-gel method to move its region of anomalous dispersion caused by IR resonance absorption towards the wavelength of CO2 laser. It is indicated by IR absorption spectra that as the content of SiO2 decreases in this glass system TiO2 and GeO2 tends to exist in their own phases. As for the gel glass with a composition of 40 SiO2·30TiO2·30GeO2, when the temperature is below 600°C, germanium atoms exist mainly in Ge−O−Ge bonds. With the temperature increasing from 800°C to 1000°C, titanium atoms in Si−O−Ti bonds abmost transform into Ti−O−Ti bonds. Furthermore, a large number of Si−O−Ti and Si−O−Ge bonds formed when the temperature approaches 800°C, which makes a notable IR absorption band round the wavelength of CO2 laser. Therefore, sol-gel based SiO2−TiO2−GeO2 gel glass is a candidate material for CO2 laser hollow waveguide.

Effects of nitric acid concentration on the stability of alumina sols

Alumina sols with a molar ratio of 1:50 between aluminum sec-butoxide (ASB) and H2O were fabricated by adding various amounts of nitric acid. The particle shape, zeta potential, polydispersity and effective particle size of alumina sol were examined by a TEM, a zeta PALS granularity analyzer and a zetaPALS zeta potential analyzer, respectively. By analyzing the change of zeta potential and double-layer thickness with nitric acid concentration, the potential energy curves of colloidal particles were mapped on the basis of DLVO theory, and the effects of nitric acid concentration on the stability of alumina sols were intensively studied. The results show that for the alumina sols with a mol ratio of 1:50 between ASB and H2O, the total interaction energy of the colloidal particle is at a maximum when the nitric acid concentration is 0.22 mol/L. Therefore, the stability of the colloid reaches optimum at the nitric acid concentration of 0.22 mol/L.

Fabrication Silver Film inside Silica Capillary

To study hollow waveguides for CO2 laser transmission, a liquid-phase deposition technique is applied to form a silver film inside silica capillary based on the method of silver mirror reaction. Using this fabrication method, the optimum combination of different parameters is gained and hollow waveguides have been made successfully with a bore size of 1mm and a guide with length of as long as 2m on self-producing apparatus. To meet quality silver film, a relative high temperature, low flowing speed and long time are adopted on the basis of low reactant concentration. The maximum transmission efficiency of hollow-core fiber without dielectric coating can be up to 85 percent and loss can be low to 0.5dB/m, maximum output power is 53W for stable 20 mintues.

Fabrication and microstructure of SiO2−GeO2 sol-gel glass coatings

SiO2−GeO2 sols and gel glass coatings with different contents of germanium dioxide were fabricated. Stable and transparent sols could only be obtained when the content of GeO2 was under 35%. It is shown by SEM that only one continuous phase is observed in the coating of 65SiO2·35GeO2 and plenty of Ge, O and Si were all found in it. However, the separated phase is found in the coating of 60SiO2·40GeO2 and a large number of Ge and O. It is proved by the Raman scattering investigation that the separated phase in the coating of 60SiO2 ·40GeO2 is germanium dioxide. The congeries of hydrolystates of Cl3 GeCH2 CH2 COOH play the main role in the formation of the separated phase when the proportion of GeO2 is much higher. Si−O−Ge, Si−O−Si, and Ge−O−Ge bonds form in the coating of 65SiO2·35GeO2 and this coating is homogenous.