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排序方式: 共有211条查询结果,搜索用时 0 毫秒
81.
82.
A. Cortes H. Gmez R. E. Marotti G. Riveros E. A. Dalchiele 《Solar Energy Materials & Solar Cells》2004,82(1-2):21
CdS thin films were deposited by chemical bath deposition onto glass substrates from chemical bath containing cadmium sulfate, thiourea and ammonia at pH=10.5. The temperature of the bath was maintained at either 75°C or 85°C and under mill stirring. After that the samples were annealed in air at 450°C. Analysis of the as-deposited thin films by energy dispersive X-ray analysis showed that almost all samples have a stoichiometric composition. The morphology of CdS films has been investigated by atomic force microscopy. The structural properties were determined by XRD and a cubic zincblende phase was present in all of the as-grown samples. Evidence of a wurtzite phase appeared after annealing. Grain sizes between 85 and 205 Å were determined from the XRD diffraction peak broadening. The sizes increase with both bath temperature and annealing. The optical properties were studied measuring the transmittance spectra. The room-temperature bandgap energies for each sample were determined from the transmittance by two different methods: extrapolating absorption coefficient and first derivative peak position. The bandgap energy varies from 2.48 to 2.35 eV following closely the quantum confinement dependence of energy against crystallite radius. This shows that the absorption edges of these samples are determined primarily by the grain sizes. 相似文献
83.
84.
AbstractInfrared radiative properties of thermal barrier coatings have been investigated for developments of solar absorbing surface coatings. Various types of multilayer broadband optical filters were designed incorporating 7 wt-% yttria stabilised zirconia (7YSZ) and aluminium oxide (Al2O3). Electron beam physical vapour deposition method was employed to deposit 7YSZ thin films on quartz substrates to study their optical properties. The refractive index and thickness of 7YSZ films were estimated using spectroscopic ellipsometry technique, giving the index as 1·95 at 633 nm. Multilayer thermal barrier coating structures were fabricated by depositing alternate layers of 7YSZ and Al2O3 on quartz using electron beam physical vapour deposition. The spectral characteristics of multilayer 7YSZ–Al2O3 coatings were evaluated using a spectrometer in the visible and near infrared range. Preliminary results obtained from multilayer 7YSZ–Al2O3 coatings had exhibited 75% transmission over a wide band of 0·4–1·0 μm. 相似文献
85.
Jongwoon Park Yong-Young Noh Jin Woo Huh JeongIk Lee Hyeyong Chu 《Organic Electronics》2012,13(10):1956-1961
We investigate the optical and barrier properties of thin-film encapsulations (TFEs) for transparent organic light-emitting diodes (TOLEDs). To improve the barrier property of OLEDs, the number of dyads (Al2O3/polymer) and the thickness of polymer layer in the TFE structure are required to be increased. It is, however, demonstrated that a sharp dip appears in the transmittance of TFE films due to the interference of light caused by organic/inorganic multi-layered configuration, resulting in a dip in the top emission spectrum of TOLEDs. We have found that such a transmittance dip deepens when the number of dyads is large. What is worse, the number of transmittance dips and their sharpness are raised with increased thickness of the polymer layer. When the number of dyads is small, however, the effect of the polymer layer thickness on such a transmittance dip is weak. Therefore, we have addressed that the number of dyads needs to be reduced, but the thickness of the polymer layer should be increased to meet both optical and barrier properties of TOLEDs at the same time. 相似文献
86.
87.
Snow density is one of the key properties to characterize a snow cover. We present diffuse near-infrared transmittance measurements with an integrating sphere setup in the laboratory. We analyze 8 snow samples taken from melt forms, decomposed, rounded, faceted and machine made snow. Reference measurements of specific surface area (optically equivalent grain size) and density are done by micro-computed tomography and used as input for transmittance calculations. A diffuse flux extinction model cannot be applied to simulate transmittance as our setup cannot be approximated by an infinite snow block thickness. Calculations with a more intricate radiative transfer model (DISORT) agree with our measurements within the estimated grain size and density variability for all probed natural snow types. Only our machine made snow shows a morphology which cannot be modeled by DISORT. Thus, our results show for the first time a direct experimental correlation between transmittance and snow specific surface area and density without the need for an empirical fitting parameter. We feel this to be an important step towards a possible high-resolution, quantitative optical measurement method to determine snow density in combination with an independent specific surface area measurement. 相似文献
88.
89.
Xiaokai Li Yangyang Xu Xiaojian Mao Qiangqiang Zhu Junxi Xie Minghui Feng Benxue Jiang Long Zhang 《Ceramics International》2018,44(2):1362-1369
Highly transparent ZrO2-doped Y2O3 ceramics were successfully synthesized using the hot isostatic pressing (HIP) process. The effects of the ZrO2 content on the sintering behaviors, optical transmission spectra, Vickers hardness, grain size, size distribution, and Raman spectra were determined. The results indicated that decreased ZrO2 content could promote increased transmittance, red-shifted infrared cutoff wavelength, increased thermal conductivity, decreased Vickers hardness, and increased lattice ordering. According to the optical transmission spectra, the optimized ZrO2 content was 0.50 at%, at which point the ceramic exhibited a larger pre-sintering temperature range of 1650–1750 °C and the average grain size of 3.35 µm at 1750 °C. The grain size was significantly decreased at lower pre-sintering temperatures. Furthermore, a moderate Vickers hardness of 8.42 GPa and high thermal conductivity of 10.85 W/m K at room temperature were obtained for the optimized ceramic. 相似文献
90.