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排序方式: 共有1620条查询结果,搜索用时 250 毫秒
61.
蒙脱石含量测定方法改进研究 总被引:1,自引:0,他引:1
用吸蓝量(MB)换算法测定蒙脱石含量,换算系数0.442不能用来准确计算其实际含量。由于吸蓝量和阳离子交换容量(CEC)与蒙脱石含量正相关,通过测定原矿、原矿提纯样以及提纯后杂质矿物的吸蓝量或CEC,进行加权或对比计算,即可得到原矿中蒙脱石的含量,这样可消除膨润土属性、属型等对测定结果的影响。改进的结果表明,不论加权法还是比值法,CEC也可用于测定蒙脱石含量;但加权法计算更为合理。蒙脱石、杂质矿物的纯度,以及它们的吸蓝量、CEC的精密度和准确度,是加权法测定准确与否的关键;比值法适用于细粒级或提纯后纯度较高情况下的测定。 相似文献
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Shanshan Ye Dan Luo Lizhen Shi Jianpeng Mou Junpeng Du Dewu Wu Jiangchong Zhou Jianyan Ding Quansheng Wu 《International Journal of Applied Ceramic Technology》2022,19(6):3367-3375
Lithium-containing silicates have been considered as a considerable alternative for luminescent materials. In this study, a novel cyan-emitting phosphor, Na3LiHf2Si3O12: Eu2+, was successfully synthesized via cationic substitution with Na4Hf2Si3O12: Eu2+ as the initial model. The crystal structure, morphology, and luminescence performance of Na4-xLixHf2Si3O12: Eu2+ were investigated in detail. The substitution of Li+ for Na+ site causes a significant blue-shift of the emission band in the range of 550–500 nm and a smaller full width at half maximum. As a result, a cyan phosphor Na3LiHf2Si3O12: Eu2+ that can be effectively excited by near-ultraviolet and high-energy beams is obtained. The mechanism of emission regulation was proposed based on the transformation of crystal structure and luminescence performance. In addition, the thermal quenching and cathodoluminescence behaviors were also studied. The results show that cation substitution is an effective method to design new lithium-containing silicate phosphors. 相似文献
64.
Roland Mainz Alfons Weber Humberto Rodriguez‐Alvarez Sergiu Levcenko Manuela Klaus Paul Pistor Reiner Klenk Hans‐Werner Schock 《Progress in Photovoltaics: Research and Applications》2015,23(9):1131-1143
Ga segregation at the backside of Cu(In,Ga)Se2 solar cell absorbers is a commonly observed phenomenon for a large variety of sequential fabrication processes. Here, we investigate the correlation between Se incorporation, phase formation and Ga segregation during fast selenisation of Cu–In–Ga precursor films in elemental selenium vapour. Se incorporation and phase formation are analysed by real‐time synchrotron‐based X‐ray diffraction and fluorescence analysis. Correlations between phase formation and depth distributions are gained by interrupting the process at several points and by subsequent ex situ cross‐sectional electron microscopy and Raman spectroscopy. The presented results reveal that the main share of Se incorporation takes place within a few seconds during formation of In–Se at the top part of the film, accompanied by outdiffusion of In out of a ternary Cu–In–Ga phase. Surprisingly, CuInSe2 starts to form at the surface on top of the In–Se layer, leading to an intermediate double graded Cu depth distribution. The remaining Ga‐rich metal phase at the back is finally selenised by indiffusion of Se. On the basis of a proposed growth model, we discuss possible strategies and limitations for the avoidance of Ga segregation during fast selenisation of metallic precursors. Solar cells made from samples selenised with a total annealing time of 6.5 min reached conversion efficiencies of up to 14.2 % (total area, without anti‐reflective coating). The evolution of the Cu(In,Ga)Se2 diffraction signals reveals that the minimum process time for high‐quality Cu(In,Ga)Se2 absorbers is limited by cation ordering rather than Se incorporation. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
65.
对732强酸性阳离子交换树脂再生铬酸盐钝化液进行了探索。研究了交换处理时间、溶液初始pH、Zn(II)初始浓度及树脂用量对树脂吸附的影响,并考察了树脂的脱附和再生性能。结果表明,该树脂对Zn(II)的吸附速率快,30 min达到吸附平衡,最佳吸附pH为3~6。用树脂再生钝化液不会对Cr(VI)浓度产生影响,能达到"去锌保铬"的目的。该树脂对Zn(II)的吸附符合Langmuir吸附等温模型,为单分子层吸附,具有吸附饱和性,饱和吸附量约为85.6 mg/g。 相似文献
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The main purpose of this work was the modification of NaX nanozeolite using copper oxide nanoparticles and various monovalent cations such as K~+, Cs~+, and Ag~+in order to make the negatively charged zeolite surface accessible for anionic forms of uranium which are the most dominant species of uranium in the contaminated radioactive waters at natural p H. Various methods such as the X-ray fluorescence(XRF), X-ray powder diffraction(XRD), field emission scanning electron microscopy(FE-SEM), transmission electron microscopy(TEM), Fourier transform infrared spectroscopy(FT-IR), and atomic absorption spectroscopy(AAS) were used to characterize the final synthesized absorbents. Batch technique was used to study the adsorption behavior of uranium ions from polluted drinking water by Na X nanozeolite and its modified forms. In order to better understand the performance of them, the results were compared with those that were obtained for synthesizing bulk NaX zeolite and Na-form of clinoptilolite natural zeolite. Preliminary results indicated that uranium sorption increased as the loading level of CuO nanoparticles on NaX nanozeolite increased from 2.1 wt% to 11.2 wt%. In addition,from the obtained data, an increase in uranium removal efficiency resulted as charge/ionic radius ratio of exchanged cation decreased. Also, the effect of contact time, solid–liquid ratio, initial concentration and temperature on the adsorption process was studied. It is worth mentioning that, in this study, the sorption of uranium was performed under natural conditions of pH and the presence of competing cations and anions which are available in drinking waters. 相似文献
68.
Effect of Cation Doping on the Superplastic Flow in Yttria-Stabilized Tetragonal Zirconia Polycrystals 总被引:1,自引:0,他引:1
Junpei Mimurada Manabu Nakano Kazutaka Sasaki Yuichi Ikuhara Taketo Sakuma 《Journal of the American Ceramic Society》2001,84(8):1817-1821
The superplastic characteristics of various cation-doped yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) were examined. For 1 mol% cation doping the true stress of Y-TZP is very dependent on the ionic radii of the doped cations; for instance, smaller cation radii give rise to lower true stress when compared with the other compositions for the same grain size, strain rate, and testing temperature. The altered true stress level must be due to the change in diffusivity of the accommodation process for grain boundary sliding caused by the addition of cations in ZrO2 . The strain to failure of the doped zirconia is affected by both ionic radius and valence of the dopant cations. 相似文献
69.
ABSTRACT In two different iron ore processing plants, it was demonstrated that when magnetite concentrate was filtered to prepare it for use as pelletization feed, the moisture that remained in the filter cake had greatly elevated levels of cations compared to the water removed by the filtration process. In particular, calcium concentrations in the filter cake were 565 times higher than in the filtrate water in Plant 1 and 19.4 times higher than the filtrate water in Plant 2. This effect is due to the adsorption of divalent cations on the magnetite surfaces resulting from electrostatic attraction when the pH of the solution is in the range where magnetite has a negative Zeta potential. Measurements of the Zeta potential as a function of pH for magnetite from Plant 2 determined that its point of zero charge (PZC) occurred at pH 3.0 to 3.5, which was much lower than is commonly reported in the literature and demonstrates that the PZC for magnetite is much more variable than is commonly thought. Plant experiments were carried out using carbon dioxide to reduce the pH of filter slurry so that the PZC could be approached. This was intended to allow adsorbed cations to be released from the magnetite surfaces during filtration. The pH adjustment was demonstrated to improve filtration rates by as much as 23%. 相似文献
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