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31.
Mushroom-like ZnO microcrystals have been prepared via a solution calcination route, using Zn(NO3)2 as Zn source in the absence of any surfactants, templates or catalysts. This is the first example to prepare mushroom-like crystals as semiconductors, which are expected to show particular physical properties. The ZnO products were investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and photoluminescence (PL) spectrum measurements. A suitable concentration of Zn(NO3)2 solution was important for the growth of the mushroom-like products. The reported synthetic procedure is straightforward and inexpensive, and thus can be readily adopted to produce large quantities of mushroom-like ZnO microcrystals. 相似文献
32.
Corrosion rates were measured at the exposed spots of rebars near three corners of Muddy Creek Bridge located in northern West Virginia using a 3LP device. Also, chloride contents of the concrete samples taken from the vicinity of the spots were analyzed using a wet chemical method that had been developed in this study. The average corrosion rate over the three spots was 4.66 mA/m2, which is in the range of corrosion damage possible in 10–15 years. The average chloride content of the concrete over the three spots was 703 parts per million (ppm), which is well above the threshold limit value of 260 ppm. Although the corrosion rate measurement method using a 3LP device is by manual operation, it is found to be reliable and effective, and, thus, recommended for future studies of this kind of research. The wet chemical method developed in this study is found to be effective. 相似文献
33.
单壁碳纳米管的制备及生长特性研究 总被引:1,自引:0,他引:1
采用Fe/MgO作为催化剂 ,催化裂解CH4制备了较纯的单壁碳纳米管 ,用TEM和Raman对碳纳米管进行了表征 ,对不同生长温度下制备的碳纳米管Raman径向呼吸振动峰 (RBM)进行了分析 ,研究了生长温度对单壁碳纳米管生长特性和结构特性的影响 相似文献
34.
岩石圈深部探测与青藏高原研究 总被引:2,自引:0,他引:2
论述了岩石圈深部探测的作用和重大意义,它是一项国土基础地质情况的调查,可以为找矿预测、地震预报、能源开发及大陆动力学研究等多目标服务,是21世纪中国区域地质调查的重要内容,是一项伟大的科学工程;美国、前苏联和中国此前均已作了大量工作,但是有待深化和进一步开展调查;简要介绍了青藏高原近些年来开展深部调查的情况和取得的主要最新成果。 相似文献
35.
富县探区三叠系延长组长6段普遍见到不同级别的油气显示,但试油未能获得工业油流.据分析,该区白垩纪末的抬升和翘倾运动使油气发生了第三次运移成藏,油、气、水重新分布并受储层物性控制.正确勾画出有利沉积相带、针对油藏特征采取更有效的工艺技术,是实现该区勘探突破的关键. 相似文献
36.
New and simple modification of vapor-liquid-solid process for Si nanowires growth based on microwave plasma enhanced chemical vapor deposition that uses solid-state Si target as a source of Si atoms was developed. The method was temperature and pressure controlled evaporation of solid phase of Si source in hydrogen microwave plasma. Aligned growth of Si nanowires was performed in local electric field by applying of constant negative bias to substrate holder. Deposited Si nanowires were studied by scanning electron microscopy (SEM), Raman and photoluminescence spectroscopy. Correlation between photoluminescence spectra and Si nanowires properties were studied. 相似文献
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39.
Theoretical predictions using a modified radical species ternary diagram for C–H–O system indicate that addition of sulfur expands the C–H–O gas phase compositional window for diamond deposition. Sulfur addition to no-growth domain increases the carbon super-saturation by binding the oxygen and the addition of sulfur to the non-diamond domain reduces the heavy carbon super-saturation by decreasing CnHm species concentration in the gas phase. The overall effect of sulfur addition to gas phase mixtures is characterized as that of oxygen addition to the C–H system, i.e. expansion of the compositional window over which diamond can be deposited from the gas phase. In addition, the increasing sulfur concentration to diamond domain feed gases beyond 2000 ppm did not affect the steady state gas phase composition but the quality of diamond was reduced. 相似文献
40.
从油气勘探、开发投资的特性出发,正确选择投资绩效评价指标,是保证评价科学性以及进行中外对比研究的前提条件。 相似文献