保险粉法合成紫外线吸收剂UV-326

以保险粉作还原剂,通过重氮化、偶合、还原反应合成了紫外线吸收剂UV-326。研究了还原反应的投料比、温度以及氢氧化钠溶液浓度等因素对反应收率和产品质量的影响。结果表明：较理想的反应条件是偶合物、保险粉与氢氧化钠的物质的量比为1：3．5：10．5,氢氧化钠溶液溶度为18％,在8l℃下反应0．5h,总产率达86％以上,产品纯度为99．9％。以该工艺合成的紫外线吸收剂具有优良的紫外吸收能力,且在500nm可见光处的透光率为99．7％。     

Grain size dependence of the bandgap in chemical bath deposited CdS thin films

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.     

单透向烟幕干扰材料及其干扰机理研究

基于二氧化硅(SiO_2)具有良好的红外透光和散射性质,探索其在单向透射烟幕配方中的应用。基于米氏散射理论分析了烟幕云团具有单向透视性能的干扰机理。其次,利用OPAG33傅立叶变换红外遥测光谱仪测试含有不同晶型SiO_2烟幕的红外透过率。结果表明:SiO_2可以作为中远距离的单向透射红外烟幕材料,在15m距离内,当烟幕位置发生变化时,红外透过率发生明显变化。说明SiO_2粒子具有良好的前向散射性能,其衰减特性与粒子的粒径和形状有一定的关系。     

Electron beam physical vapour deposited zirconia based ceramics for developments of solar surface coatings

Abstract

Infrared 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.     

Optical and barrier properties of thin-film encapsulations for transparent OLEDs

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.     

高透光细瓷的制备

实验以锂瓷石、石英、龙岩高岭土、钾长石、烧滑石为主要原料制备坯体,通过采用外加腐殖酸钠和膨润土来调节高透光细瓷坯体的成形性能;并通过单因素和正交实验考察了配方组成对高透光细瓷性能的影响。当配方(质量%)为:锂瓷石40、石英27、龙岩高岭土32、钾长石8、烧滑石1.5、膨润土2、熔块2、腐殖酸钠0.8、氧化铝2,在还原气氛1320℃烧成,制备了高透光细瓷。该细瓷透光度可达27.5。     

First experiments to determine snow density from diffuse near-infrared transmittance

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.     

Investigation of optical,mechanical, and thermal properties of ZrO2-doped Y2O3 transparent ceramics fabricated by HIP

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.