Papers by Keyword: Infrared Transmittance

Abstract: (100-x)Ge₂₃Se₆₇Sb₁₀-xRbI glasses were prepared by the melting technique. The structures and properties were investigated by using SEM, XRD, DSC, FTIR and Vickers hardness tester. It is found that, with increasing x, the glass-forming ability and the infrared transmittance of (100-x)Ge₂₃Se₆₇Sb₁₀-xRbI samples decrease, the thermal stability and the fracture toughness increase, the Vickers hardness increases first and then decreases. When the content of RbI is 1%, the hardness reaches the maximum value 1985 MPa, at this point, the fracture toughness reaches 10.41 MPamm^1/2.

Abstract: Germanate oxyfluoride glass in CaF2/BaF2-AlF3-SiO2-GeO2 was prepared by melt quenching technique and subsequently converted to glass-ceramics with microstructures comprised nano-crystallites in a residual glass matrix by two-step heat treatments process. DSC, XRD, SEM and IR transmission investigations were used to determine structural characteristics and optical property of the prepared germanate oxyfluoride glass-ceramics. The influences of heat treatment conditions on crystallization behaviors and infrared transmission were discussed. The results show that crystal phase in the glass-ceramics is only Ge2Al6O13 and the crystal size is about 20nm-80nm when treated temperature ranges from 900 oC to 960oC. Good transparency is exhibited in visible light band to midinfrared band (5.0um) when treated temperature is low than 940 oC.

Abstract: The growth of polycrystalline curved surface diamond film using direct current plasma jet CVD (DCPJCVD) is measured by those techniques. The relationships between morphology, microstructure, and film quality are investigated by scanning electron microscopy (SEM) and Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), respectively. The results show that, after molybdenum substrate was polished by series of diamond powder, atom hydrogen etching, respectively, a much higher nucleation density can be achieved. Synthetic diamond film is compact, continuous and uniform, and diamond film grows with the columnar spreading from the nucleation surface to the growth surface, (111) faces were dominant in polycrystalline texture diamond film. Raman spectrum indicates that there is only diamond characteristic peak in diamond film, and high quality curved surface diamond film was prepared. IR transmittance of curved surface diamond film in the range of 750 - 4300 cm-1 reached about 60%. Meantime, the IR transmittance was almost the same in the central and fringe regions of the film. These properties indicate that curved surface diamond film has a promising application in infrared windows and dome.

Abstract: Germanium carbon films were prepared on ZnS substrates by reactive RF magnetron sput- tering of a Ge target in Ar and CH4 mixtures for IR antireflective and protective purposes. IR transmit- ttance spectra of the specimens were measured, with which H content in the films was investigated. The C and Ge contents and the atomic binding state were studied by X-ray photoelectron spectroscopy. The results show that H involved in the films combine mainly with C at low substrate temperatures. IR absorption peaks caused by the C-H bonds decrease with increasing temperature, indicating the drop of the C-H bonds content in the film. At relatively low temperature the film is high in C content and low in refractive index; at high temperature the film is low in C content and high in refractive index. Both C-Ge and C-C bonds exist in the film and O impurity combines mainly with Ge.

Abstract: The optical-grade diamond film was prepared by DC plasma jet CVD method, and a double-sided polishing was made by EDM and mechanical polishing technology. The investigations of the internal stress at different temperature on the infrared transmission were tested in detail. SEM and AFM were used to study the polished surface morphology, surface roughness was 0.12nm and 0.25nm. XRD and Raman were characterized on the diamond films, the results showed a higher intrinsic quality. The internal stress distribution and infrared transmittance were investigated at 25°C and 100°C temperature respectively. The infrared transmission mechanism of diamond film was also discussed. The main reason of decreasing of infrared transmittance was the increasing grain collisions, which caused more scattering and absorption of incident light with temperature increasing.

Abstract: Long-wave infrared windows and domes used under harsh conditions always suffer sand abrasion and raindrop erosion. GaP thin film has proved to be effective LWIR protective coating for zinc sulphide window. In this article, the GaP films have been deposited on 5-mm-thick thermo-pressed planar ZnS substrates by RF magnetron sputtering in high pure Ar gas, with a single crystalline GaP disc as the target. The maxima of the GaP/ZnS transmission spectra curve are less than the corresponding transmissivities of ZnS substrates, which indicates that the GaP films are of absorption. SEM results show that the films are very compact and their surfaces are glazed. XPS analysis shows that gallium content is more than phosphor content in the films, and oxygen is the main impurity. The more the gallium content is, the more absorption the film is of. The absorption does not vary greatly with oxygen content. So the absorption of the film is caused mainly by the overfull metal component, which increases the conductivity and causes the charge carrier absorption. Low absorption GaP film with the thickness more than 10 µm has been deposited, in which the Ga:P ratio is nearly 1:1.