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931.
Nuengruethai Ekthammathat Titipun Thongtem Anukorn Phuruangrat Somchai Thongtem 《稀有金属(英文版)》2011,30(6):572-576
Monoclinic and hexagonal CePO4 nanoparticles and nanorods were successfully synthesized from Ce(NO3) 3·6H2O and Na3PO4·12H2O solu-tions at pH 1-5 by a 180 W microwave radiation for 60 min.The products were characterized by X-ray diffraction(XRD) ,Fourier transform infrared(FTIR) spectroscopy,and scanning electron microscopy(SEM) .XRD patterns revealed that the products are hexagonal CePO4 structures at pH 2-5,and monoclinic CePO4 structures at pH 1.SEM characterization shows that these products were nanoparticles,short nanorods,and long nanorods,controlled by the pH of the precursor solutions.Optical properties of the nanorods were also investigated by ultraviolet-visible(UV-vis) and photoluminescence(PL) spectroscopy. 相似文献
932.
Controlling novel morphologies and developing effective doping strategies are two important tasks for advancing ZnO and CdO based nanomaterials. Modulation of band energies through size control offers new ways to control photoresponse and photoconversion efficiencies of the solar cell. The P-type semiconductors of copper oxide and zinc oxide are an important functional material used for photovoltaic cells. CuO is attractive as a selective solar absorber since it has high solar absorbance and a low thermal emittance. This work describes the synthesis and characterization of semiconducting nanoparticles (ZnO, CuO, CdO, Cu-ZnO, Cu-CdO) via one-step, solid-state reaction in the presence of polyethylene glycol 400.Solid-state mechanochemical processing—which is not only a physical size reduction process in conventional grinding but also a chemical reaction that is mechanically activated at the nanoscale during grinding. The present method is a simple and efficient method for the preparation of nanoparticles with high yield at low cost. The structural and chemical composition of the nanoparticles were analyzed by X-ray diffraction, field emission scanning electron microscopy and energy-dispersive spectrometer (FESEM/EDAX). Optical properties and band gap were studied by UV-vis absorption spectra. XRD data has been concluded that the Cu doping induced the lattice constants to change to some extent. These results have showed that the band gap energy decreases with increase in annealing temperature, which can be attributed to the improvement in crystallinity of the samples. The band gap of the Cu-ZnO and Cu-CdO crystals can be tuned in the range of 3.34-3.28 eV and 2.80-2.21 eV respectively, by the use of dopants. 相似文献
933.
A new low band gap electrochromic polymer containing of 3-(2,5-di-2-thienyl-1H-pyrrol-1-yl)-9-ethyl-9H-carbazole (SNSC) and 2,1,3-benzoselenadiazole (BSe) moiety has been reported. Structural identification of initial compounds and product were carried out by using FT-IR and 1H NMR spectroscopy results. The resulting polymer, poly(SNSC-BSe), was completely soluble in various common organic solvents and its weight-average molecular weight (Mw) were 9420 (PDI: 1.22). According to AFM results, the RMS (root mean surface) roughness of poly-(SNSC-BSe) was found to be 48.6 nm. Besides, the thermogravimetric analysis presented that the poly(SNSC-BSe) is moderately stable against to thermal effect with the initial degradation temperature at 182 °C. The lowest energy transition band maxima of poly(SNSC-BSe) was 498 nm in thin film and the optical band gap calculated from the onset wavelength of the optical absorption was 1.77 eV. On the other hand, the electrochemical band gap calculated from oxidation and reduction onset values was 1.60 eV, respectively. Finally, the electrochromic performance of the polymer film represents a high contrast ratio in the NIR region (51%), fast response time of about 1 s, high coloration efficiency (274 cm2 C−1) and retained its performance by 94.6% even after 1000 cycles. 相似文献
934.
介绍尿素装置离心式高压甲铵泵一次事故后比较艰难的修复经过,总结检修中的经验教训和应注意问题,并对事故原因进行分析。 相似文献
935.
通过对水利灯泡贯流式机组长期运行存在的故障隐患分析,阐述飞来峡机组空气间隙在线监测系统建立的必要性,介绍目前机组空气间隙在线监测系统的构成、设备选型、系统与监控系统接口等情况,最后通过TN8000软件对机组气隙等状态进行在线监测,对任一时间段的实时采样数据进行积累统计产生图形和分析报告,便于对机组的健康状态进行分析和评估。 相似文献
936.
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938.
本文分析了再制造系统风险管理与知识需求的关系,提出了提高再制造系统风险管理水平的知识需求链,并通过对再制造过程实践的分析,识别出风险管理实施过程中存在的6大知识缺口的原因,构建基于知识管理的再制造风险管理模式,该模式能从根源上弥补风险管理中的知识缺口,并为再制造风险管理实践提供了知识来源和控制流程。 相似文献
939.
简述了三辊式定(减)径机的传动方式以及目前普遍使用的相邻机架辊缝的相位关系;分析了热轧钢管使用三辊式定(减)径机时产生"内六方"缺陷或缺欠的主要原因;提出了用增加定(减)径机机座工位、改变机架的布置方式和传动方位、减小相邻机架辊缝相位角的想法,以期达到将"内六方"转变为"内十二方",提高钢管壁厚精度的目的。 相似文献
940.