共查询到19条相似文献,搜索用时 109 毫秒
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采用自悬浮定向流法制备出Ag2Al复合金属间化合物的纳米微粉,通过透射电子显微镜、X射线衍射仪和X射线能谱仪对纳米微粉的显微结构、粒度、相组成和成分构成进行研究。结果表明:所制备出的复合金属间化合物纳米颗粒呈规则球形,粒径分布在20~110 nm之间;纳米合金颗粒的主要组成相为Ag2Al,并伴有少量的Al;样品中的Ag,Al原子数比约为66.5∶33.5,金属间化合物纳米颗粒中Ag2Al晶粒尺寸约为33 nm,Al的约为21 nm。 相似文献
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简要叙述了自悬浮定向流方法制备铜纳米粉末的原理和包覆层薄膜的生长机理,采用空心阴极辉光放电对铜纳米粉末进行有机包覆,实验中CH4和H2的流量分别为6 ml/min和12 ml/min,工作电压为450 V,衬底与空心阴极的底端距离为2 cm,背景真空和工作气压分别为6 Pa和100 Pa,沉积速率为7.5 nm/min。用透射电镜(TEM)对铜纳米粉末进行了观察和分析,结果表明:铜纳米粉末呈球状,其粒径分布在10~100 nm之间, 平均粒径大小为50 nm;其包覆层的厚度大约为15 nm,而且该厚度可以通过调节空心阴极辉光放电的参数来控制。 相似文献
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采用自悬浮定向流法制备了金属纳米粉体并采用真空手套箱专利技术和冷压法在高压(1.5 GPa)作用下保压40 min后,成功制备出了相对密度达97%和显微硬度达1.85 GPa的金属Cu纳米晶材料。经XRD分析,其晶粒大小为20 nm。正电子湮没(PAS)实验结果表明,其空隙大小和数量与采用惰性气体冷凝法原位压制(IGC)的样品相比,空位簇数量较多,微空隙的大小和数量基本相当。激光惯性约束聚变(ICF)模拟实验表明:采用该方法制备的纳米Cu块体材料靶的激光转换效率比常规Cu材料靶高5倍。 相似文献
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研究利用电磁感应加热一自悬浮定向流技术合成金属纳米粉末。然而,这种技术很难制备出高熔点的金属纳米粉末,如W,Mo。而超声波辅助电解方法正好可以弥补这个缺陷。尽管超声波辅助电解方法操作简单,但是它能合成高产额的纳米粉末。因此,这种方法很适合于工业生产。 相似文献
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根据工作实际需要出发,开展了与惯性约束聚变物理实验用靶材料密切相关的3方面的初步研究,并且取得了一定成果。这3个方向为:(1)自悬浮定向流纳米金属粉末制备的理论模拟;(2)分散剂对间苯二酚-甲醛(RF)有机气凝胶掺杂过程的影响;(3)微波等离子体刻蚀技术初步研究。 相似文献
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彩色负片的颗粒性能是一个重要的质量指标。以往颗粒性能的度量采用均方根颗粒度的方法。均方根颗粒度建立在只对彩色负片进行灰密度(白光调制)采样的基础之上,难以保证所测数值与实际扩印照片效果相符合。采用对彩色负片进行红、绿、蓝三色光调制密度采样的方法,从三色均方根颗粒度出发,结合扩印过程中颗粒性能的传递特性以及观察照片时人眼的视觉生理和心理特性等诸多因素,形成一个代表最终照片颗粒效果的知觉颗粒度,称为彩色负片的印片颗粒指数(PGI)。实际测试和观测比较表明,所测彩色负片印片颗粒指数数值与其扩印效果相符合,印片颗粒指数方法能够反应彩色负片颗粒性的实用效果。 相似文献
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《X射线光谱测定》2005,34(3):245-252
An alternative preparation method for samples containing high levels of biogenic and organic matter with respect to automated electron probe microanalysis (EPMA) measurements was investigated. The organic and biogenic particles were impregnated with a heavy metal (Ru), causing an increase in the average atomic number of the particle. After impregnation, biogenic and organic particles give better contrast in backscattered electron images and can be traced by automated EPMA. During the interpretation of the results, attention was focused on the differences in the detected abundances of organic and biogenic particles and the relative importance of different particles types in the impregnated and non‐impregnated samples. The results obtained for particle diameters larger than 0.7 µm show that the method could be successfully applied to samples with a high contribution of coarse biogenic and organic particles. The impregnation of the particles with a heavy metal results in more efficient detection of smaller particles, which implies that the particle size distribution can be obtained more correctly. A second benefit of the impregnation method is the detection of a larger number of particles, which has an important influence on the calculation of the absolute abundances. The apparent abundance of the biogenic and organic particles was clearly higher in the treated samples. Moreover, in the case when only the conventional EPMA technique with a Be detector window is available, this method can be applied for the identification of organic and inorganic agglomerates. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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植物样品消解后残留颗粒物元素组成研究 总被引:8,自引:0,他引:8
分别采用干灰化法和湿消化法处理植物标准参考物质灌木枝叶组合样(杨树叶和茶叶),用扫描电镜(SEM)对消解液中残留的不溶性颗粒物微观形貌进行了观察,并用SEM附属的X能谱仪研究了颗粒物的主要元素组成。另外,还用BCR法对茶叶残留颗粒物进行了分级萃取, 相关元素在四种存在形态中的含量分布状况由AAS和ICP-AES给出。研究结果表明:不同消解方法对颗粒物微观形貌有较大影响,其中植物样品经干灰化法处理后残留的颗粒物多呈灰黑色,表面疏松多孔;经湿消化法处理后残留的颗粒物均呈白色,多数结构紧密,数量也相对较少。不同植物样品残留的颗粒物元素组成均大同小异,主要为Si和Al,此外还有少量的Ca, Fe, K, Ti等。这些元素在颗粒物中存在形态不一,致使在进行植物样品分析时某些元素含量测定结果大为偏低。 相似文献
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采用化学气相沉积技术,利用旋转涂膜法制备催化剂基底材料,通过对涂膜过程中的角速度、旋转时间以及基底还原过程中温度的控制改变催化剂颗粒的分布状态,获得了粒径均匀分布的催化剂基底,该基底上催化剂颗粒集中分布在47~62 nm区间,再利用该基底生长出定向碳纳米管阵列。运用扫描电镜、透射电镜、拉曼光谱仪对样品进行了表征。结果表明旋转涂膜法制备的基底平整性好于普通的滴膜法,且较其它基底制备方法具有简单易控、可使催化剂均匀分散等特点。利用该基底制备的碳纳米管阵列定向性良好。 相似文献
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采用多角度动态光散射和加权正则化反演方法,对4组模拟的双峰分布颗粒体系(100/600 nm,200/600 nm,300/600 nm和350/600 nm)分别选取1、3、6和10个散射角进行测量.粒度反演结果表明,采用加权正则化方法反演双峰颗粒体系的多角度动态光散射测量数据,可获得峰值位置比小于2∶1且含有大粒径(>350 nm)颗粒的双峰颗粒粒度分布.采用标准聚苯乙烯乳胶颗粒进行实测的结果验证了这一结论.得到含大粒径颗粒的双峰粒度分布反演结果的原因在于,多角度动态光散射能提供更多的大粒径颗粒的粒度信息,加权正则化反演方法能减少测量数据中的噪声,因而多角度动态光散射测量数据的加权反演能实现峰值位置比小于2∶1且含有大粒径颗粒的双峰颗粒体系的测量. 相似文献
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Fabrication and characterization of drug particles produced by electrospraying into reduced pressure
In the present study, electrospraying was used in drug particle-production. The objective of the research was to establish whether electrospraying can be carried out in reduced pressure in order to improve the drying process of the droplets. By this method, it is possible to produce drug particles relatively uniform in size, crystallinity and porosity. Drying the droplets in a reduced pressure is a more sensitive way to remove the solvent from the particles than, for example, the addition of heat. The efficiency of this drying method and particle morphology were studied using SEM, DSC, and XRD. Another objective was to workout whether the size of the produced particles can be estimated by a simple method. The maximum particle size was defined theoretically and compared to experimental results with good agreement. 相似文献
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A. Donini E. Fernandez-Martinez P. Migliozzi S. Rigolin L. Scotto Lavina M. Selvi T. Tabarelli de Fatis F. Terranova 《The European Physical Journal C - Particles and Fields》2008,53(4):599-606
High density magnetized detectors are well suited to exploit the outstanding purity and intensities of novel neutrino sources
like neutrino factories and beta beams. They can also provide independent measurements of leptonic mixing parameters through
the observation of atmospheric muon-neutrinos. In this paper, we discuss the combination of these observables from a multi-kT
iron detector and a high energy beta beam; in particular, we demonstrate that even with moderate detector granularities the
neutrino mass hierarchy can be determined for θ13 values greater than 4°.
PACS 14.60.Pq; 14.60.Lm 相似文献