Kee-Sun Lee

Effect of TiNx inter/outer layer on Ag(Cr) thin films at elevated temperatures for low emissivity applications

TiNx/Ag(Cr)/TiNx multilayer thin films have been deposited at room temperature on soda lime glass substrates by using RF and DC magnetron sputtering. Ag(Cr) films were deposited by using the Cr chips embedded pure Ag mosaic target. In this report, a rigorous analysis has been performed on the optical properties and the effect of TiNx thin film as an inter/outer layer. The deposited tri-layer films were post annealed at 873 K for 5 min to clarify the low-emissivity (low-e) properties at high temperatures. Proposed multilayer stack exhibited noticeable low-e properties with the smooth surface topography, high visible transmittance and low infrared transmittance. In addition, no outward/inward diffusion of Ag was observed during the post annealing at 873 K. The obtained results suggest that the films were thermally stable even at 873 K with no compromise in the low-e properties. Low-e value of the deposited films was estimated as 0.07 from the sheet resistance.

SiO2/TiO2/n-Si/Ag(Cr)/TiO2 thin films with superhydrophilicity and low-emissivity

In this study, SiO2/TiO2/n-Si/Ag(Cr)/TiO2 multilayer structures have been designed and deposited by the RF and DC magnetron sputtering at room temperature. The as-deposited TiO2/glass films which are initially amorphous in nature were subjected to post annealing at 673 K for anatase phase TiO2. The anatase TiO2 films showed an optical bandgap ~3.32 eV. The Ag(Cr)/TiO2 showed very low-emissivity (low-e) value ~0.081 which is evaluated by using the sheet resistance (6.51 Ω/) of the films. All the deposited films showed high visible transmittance (~81%) and high infrared reflectance (72%) which are recorded by using the UV–vis–NIR spectrophotometer. In addition, experimentally obtained optical properties were in good agreement with the simulation data. The TiO2/n-Si heterojunction concept has been employed to enhance the superhydrophilicity of the deposited multilayer stack, TiO2/n-Si/Ag(Cr)/TiO2 films exhibited best superhydrophilicity with water contact angle ~2°. The deposited multilayer structures SiO2/TiO2/n-Si/Ag(Cr)/TiO2 and TiO2/n-Si/Ag(Cr)/TiO2 achieved significant low-e and superhydrophilicity.

Si-FeSi 2 /C nanocomposite anode materials produced by two-stage high-energy mechanical milling

High capacity retention Silicon-based nanocomposite anode materials have been extensively explored for use in lithium-ion rechargeable batteries. Here we report the preparation of Si-FeSi2/C nanocomposite through scalable a two-stage high-energy mechanical milling process, in which nano-scale Si-FeSi2 powders are besieged by the carbon (graphite/amorphous phase) layer; and investigation of their structure, morphology and electrochemical performance. Raman analysis revealed that the carbon layer structure comprised of graphitic and amorphous phase rather than a single amorphous phase. Anodes fabricated with the Si-FeSi2/C showed excellent electrochemical behavior such as a first discharge capacity of 1082 mAh g-1 and a high capacity retention until the 30th cycle. A remarkable coulombic efficiency of 99.5% was achieved within a few cycles. Differential capacity plots of the Si-FeSi2/C anodes revealed a stable lithium reaction with Si for lithiation/delithiation. The enhanced electrochemical properties of the Si-FeSi2/C nanocomposite are mainly attributed to the nano-size Si and stable solid electrolyte interface formation and highly conductive path driven by the carbon layer.