Guangzhong Yuan

In situ optical characterizations of the annealing effects upon SnO2:F films by spectroscopic ellipsometry

In situ study of the annealing effects, up to 600 °C, upon the optical performance of SnO2:F films have been successfully conducted with spectroscopic ellipsometry. The thickness and optical parameters were obtained by the regression of the measured ellipsometry parameters using a five-layer model. The results show that the re-densification of the SnO2:F layers occurs at above 200 °C, resulting in an irreversible thickness reducing from about 326 nm to about 321 nm. The refractive index of the SnO2:F layer increases with temperature and decreases in the cooling period. The in situ temperature dependence of the average refractive index has a good agreement with the sheet resistance measurement results, not only verifying the annealing process deteriorates the low-emissivity performance, but also demonstrates that spectroscopic ellipsometry method is a suitable optical characterization technique to adjust the on-line coating process of float glass.

Study of annealing effect upon the structural and solar- selective properties of C/Ni/NiO composite coatings prepared by sol–gel method

AbstractThe Ni/C/NiO composite thin films have been prepared by one-step sol–gel method. The prepared samples were annealed at 450 °C with different holding times. When the metallic nickel nanoparticles were homogeneously dispersed in the composite, it is observed that both NiO and metallic Ni are surrounded by resident carbon. Comprehensive analysis techniques have been carried out in order to analyze the structural, optical, and solar- selective absorber properties of the composite. The main structure variations with various holding times are (i) the decrease in thickness and (ii) enhancement of metallic Ni nanoparticles size. The solar-selective absorber properties for one-layer Ni/C/NiO composite film annealed at 450 °C with 10 min of holding time show the optimal performance in the present work, exhibiting an absorbance of about 0.80 and an emittance of about 0.11, and capable of a good candidate as SSA for the low–middle temperature applications.

Marangoni effect induced macro porous surface films prepared through a facile sol-gel route

Based on TiO2 as a model system, the sol-gel one step facile method is established to fabricate the macro-porous morphology films on the basis of Marangoni effect. In this proposed mechanism, the binary mixture of hydrophilic CuCl2 and lipophilic Ti-O network is used in sol to produce phase separation. A suitable evaporation rate in the gel film process leads to the macro-porous film due to Marangoni effect. It is observed that the macro-porous morphology of the film sustains during the annealing process, which suggests the creation of porous surface morphology in gel film stage rather than due to annealing. To analyze the preparation mechanism, the sol-gel process and microstructure of films are examined using TG-DTA, SEM, TEM, XRD, Raman, UV-Vis, XPS and FTIR. Furthermore, the optical-thermal properties are studied for the potential applications of such porous surface films as solar selective absorber.