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Homogeneous (ZrO2)0.92 (Sc2O3)0.08 solid solution in fluorite cubic structure was prepared from the gels with altered molar ratios of citric acid (CA) to metal ions (M) and ethylene glycol (EG) via a polymerization route (Pechini method). Due to the enhanced chemical homogeneity (high level of mixing of metal ions and ligands) in the polymeric gels, Sc-doped zirconia can be crystallized at temperatures as low as 400 ~C. During the evolution from amorphous gel to the crystallized (ZRO2)0.92 (Sc203)0.08 fine powder, the bonding nature between carboxylate groups and Zr/Sc cations changed: unidentate→bridging→ionic upon calcination. The molar ratios of CA/M (1~4) and CA/EG (0.2~4) were demonstrated to affect the thermal behavior of the gels and thus the particle properties of the derived nanoparticulate oxide powders (including particle size and surface area). The as-sintered sample compacted from the nanosized powders prepared by calcining the gel with the highest content of organics (CA/M =4and CA/EG=0.2) exhibited the best sinterability and the highest oxide ion conductivity. 相似文献
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Asabranchofsuperamolecularchem istry ,lanthanidecalixarenechemistryhasat tractedconsiderableresearchinterestforsever alyears[1~ 5 ] .Inthisrespect,Harrowfieldetal.[6~ 13] synthesizedalotoflanthanidecal ixarenecomplexes ,andrevealedtheircrystalstructures .Amongstt… 相似文献
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串级萃取理论的进展及其在稀土工艺中的应用 总被引:3,自引:0,他引:3
本文简要地介绍了串级萃取理论的提出与发展的过程及其与我国稀土萃取分离实践的紧密联系;该理论已应用于稀土和钴镍等的工业生产,并取得了一定的经济效益。文中简要地介绍了串级理论Ⅰ—Ⅷ各文的主要内容,并收集了一些关于理论应用及对理论评述的资料与文章。本工作可以解决以下问题:(1)可以为一个待设计的工艺或待改造的工艺提供数组合理的工艺设计参数,以供根据各自情况择优选取;(2)设计了一系列计算程序,完全模拟了“漏斗法”的串级实验的全过程,使计算机技术可以代替人工实验,并能快速、准确地获得串级萃取过程中的大量信息,这是人工实验中无法实现的。(3)使串级萃取工艺的理论设计有可能一步放大到工业试验,从而可缩短试验周期;并为由于原料、产品或设备等条件的变化,需迅速调整工艺参数提供了一个可靠的方法。 相似文献
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Computer simulation of the preparation process loading rare earth(RE)directly from acidic extractant and RE chloride was established using MATLAB software.The mechanism of the extraction reaction was assumed,and then an experiment was conducted to confirm the mechanism and the apparent equilibrium constant of the reaction was determined as well.Owing to the involvement of H+ ion in the reaction between acidic extractant and RE chloride,the computer simulation of the process was more complicated than that of the extraction only between different rare earths.In the present work,MATLAB software was therefore introduced to handle the resolution of the complicated processing equation,and the simulation was performed by varying some key parameters including feed composition and phase ratio,etc.Consequently this work presented a simple method to simulate the H+ ion involved countercurrent extraction process of rare earths and also provided the practical references for the relative process designing. 相似文献
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ApplicationofthePhaseTransferCatalysisinRareEarthSolventExtractionYanChunhua(严纯华);ZhangYawen(张亚文);LiaoChunsheng(廖春生);JiaJiang... 相似文献
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For an AB/BC countercurrent extraction separation using organic feed, the conditions to have minimum amount of ex- tracting solvent (Smin) and minimum amount of scrubbing agent solution (Wmin) were discussed, and the formulae of both Sroin and Wmin were deduced. It was shown that only when the ratio of flowrate of central component B leaving aqueous outlet to that leaving organic outlet took a certain optimal value, the AB/BC separation could have Smin as well as Wmin, and this optimal ratio was decided by the separation factors between the three components but independent of feed composition. Smin was only relative to the separation factor of A/C pair but regardless of the separation factors of other pairs as well as feed composition, whereas Wmin was determined by the separation factors between the components together with feed composition. Meanwhile it was also found that the organic stream out of feed stage was same composition as the initial organic feed when the separation system was given by the two minimum amounts and its steady state was achieved. Finally the results above were used to design a LuYb/YbTm separation case and the stage-wise compositions of each component in both the organic and the aqueous phase at steady state were given by computer simulation. 相似文献
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经过近20年的发展,纳米科学的研究对象已从早期的Ⅱ-Ⅵ族半导体体系、碳簇和碳管体系拓展到了包括主族元素化合物、过渡金属及其化合物、贵金属及其合金,以及镧系元素化合物等更为丰富的体系,研究的方法也从早期的溶液相合成拓展到多相合成、模板法合成,以及仿生合成等复杂方法,研究目的也从单纯的材料纳米化转为以功能和器件为导向的合成和组装,并且更加注重材料的组成、结构、形貌和表界面的控制,以及在催化、信息、生命等领域的的应用。显然,无机合成化学已成为纳米材料和器件制备不可或缺的重要手段。业已证明,溶液法不仅具有纳米材料在合成中的可控性,而且具有工业化开发和生产前景。以近年来稀土功能材料体系的控制合成为例,阐述纳米或介观材料溶液法合成中有关前驱物选择、晶粒成核和生长控制、材料尺寸、结构、表面和晶面控制等方面的优势,同时讨论稀土功能纳米材料在相关领域中的应用。 相似文献