高纯稀土金属Sm、Yb和Tm的制备（英文）

采用镧热还原蒸馏法对蒸气压较高的稀土元素Sm、Yb和Tm的制备进行了研究,制得了纯度达4N级的稀土金属Sm和Yb,其纯度分别为99.99%和99.993%(质量分数,相对75种杂质元素);对于稀土金属Tm,由于还原温度较高,还原蒸馏产物中La的含量偏高,需要对其进行低温、高真空升华提纯,提纯后纯度达到99.995%(同上)。结果表明,高纯度还原剂La的制备,尤其是La中金属杂质总量的控制,是获得99.99%纯度Sm、Yb和Tm的关键步骤。     

高纯金属铒的制备工艺研究

高纯金属铒是多种功能材料的原材料,其纯度对材料性能有较大影响,结合稀土金属制备工艺,系统研究高纯金属铒制备工艺,为工业生产提供依据。分析氟化铒等原料物像对还原过程的影响,确定最佳还原工艺条件:还原剂过量10%,1570℃保温10 min,金属收率大于95%,分析不同设备对金属纯度的影响,高真空和清洁蒸馏环境的钽片炉多次蒸馏可制备99.9904%(质量分数)的高纯金属铒。     

高纯铁制备技术综述

本文介绍了溶剂萃取、离子交换、电解精炼和区域熔炼等冶金提纯方法在高纯铁制备过程中的应用。采用溶剂萃取法和离子交换法,可以除去溶液中的大多数金属杂质,得到纯度为4N的高纯铁溶液。通过氢还原或电解精炼,可进一步去除杂质元素并获得纯度为6N的金属铁材料。区域熔炼法可对铁进行进一步精炼,使纯度达到极限。对不同的原料纯度以及不同的产品纯度要求,采用的工艺方法也有相应的变化,但一般采用几种方法相结合的工艺路线制备品质优良的高纯铁。     

Yb掺杂蓝色荧光材料GdVO4:Tm的发光性能

以柠檬酸作为络合剂,采用溶胶-凝胶法制备不同Yb含量的纳米级蓝色荧光材料GdvO_4:Tm.采用XRD、荧光光谱仪、SEM对产物的相组成、发光性能和颗粒形貌进行了分析.结果表明,所得掺杂Yb的GdVO_4:Tm蓝色发光粉体,粒度约80 nm;在260～310 nm的紫外光激发下,发出明亮的蓝色荧光;当Yb含量在1%(摩尔分数,下同)时,粉末的发光性能最好.     

纳米氧化铝粉体的绿色合成

以廉价的铝锭和异丙醇为起始原料,采用独特的分离提纯、回收再利用技术和溶胶凝胶工艺,合成高性能纳米氧化铝粉体,并利用TEM,XRD和石墨炉原子吸收法等对粉体的相组成、形貌和杂质含量进行分析研究.得出原料对粉体的形貌和组成没有影响,两种不同的Al源均制备出了粒径为10～20nm,球形γ-Al2O3粉体;而原料和蒸馏工艺对纳米氧化铝粉体的纯度有影响,随铝锭纯度的增加,所制备的纳米氧化铝所含的微量杂质含量明显下降.和一次蒸馏相比,二次蒸馏所得产物的主要微量杂质明显下降.利用重熔铝锭为原料,采用二次蒸馏工艺,制得了纯度高达99.99%的纳米氧化铝,且在制备过程中没有废液,废气排出,实现了高纯纳米氧化铝粉体的低成本、环保型生产.     

Lu_2O_3:Yb~(3+),Tm~(3+)纳米晶的制备和上转换发光性能(英文)

采用碳酸氢铵(NH4HCO3)为沉淀剂,用共沉淀法制备Yb3+和Tm3+共掺杂的Lu2O3:Yb3+,Tm3+纳米晶。研究Tm3+摩尔分数、Yb3+摩尔分数和煅烧温度对Lu2O3:Yb3+,Tm3+纳米晶的结构和上转换发光性能的影响。结果表明:所制备的纳米晶具有纯的Lu2O3相,结晶性较好。当掺杂的Tm3+浓度超过0.2%(摩尔分数)时,出现浓度淬灭效应。Tm3+和Yb3+的最佳掺杂比分别为0.2%和2%(摩尔分数)。在980nm半导体激光器的激发下,样品发射出蓝光(490nm)和红光(653nm),分别对应Tm3+的1G4→3H6和1G4→3F4跃迁。发射强度与激发功率的关系表明,Tm3+的1G4能级布居是三光子能量传递过程。随着煅烧温度的升高,上转换发光强度增强,这主要是因为随着温度的升高纳米晶表面的OH?减少和纳米晶尺寸增大。     

R3Co29Si4B10硼化物的磁性

土耳其Nevsehir大学AyseOzdemir等人用Ⅺ射线粉末衍射和磁性测量研究四元稀土金属间硼化物RaC029Si4810（R—La,Ce,Pr,Nd,Sm,Gd,Dy）。测定结果表明,R3C029Si4B10化合物为正方晶结构,属于P4／nmm组。R—La,Ce,Pr,Nd,Sm时,该硼化物为铁磁体;当R—Gd、Dy时,硼化物为亚铁磁体,居里温度变化于149K和210K之间。     

La2O3:Sm3+纳米发光材料的燃烧法合成及其性能研究

通过燃烧法制备了La2O3:Sm3+纳米材料,用XRD和TEM对其形貌结构进行了表征和分析,并研究了其发光性质。结果表明：La2O3:Sm3+纳米材料为六角结构,颗粒尺寸大约为34 nm; Sm3+的掺杂引起其衍射峰的位置发生略微的右移; Sm3+的本征激发带位于411 nm左右;在近紫外光（411 nm）的激发下,观察到 4G5/2 → 6H5/2 (568 nm)、 4G5/2 → 6H7/2 (611 nm, 强度最高) 和 4G5/2 → 6H9/2 (654 nm)三个主发射峰;发射光谱表明La2O3:Sm3+中Sm3+离子的格位对称性较低;材料样品的衰减寿命约为202 us,色度坐标大约为(0.5849, 0.4143)。     

电镀技能考题汇编（连载）

39、镀液中杂质的来源有哪些？怎么控制？答：镀液中杂质的来源主要有以下几个方面,应有针对性地采取相应措施予以控制;（1）加入的化学药品纯度低、杂质多;应采用纯度较高的化学药品（如电镀级或化学纯）,并应定点进货。（2）阳极材料纯度低;应采用纯度高的极板。（3）挂具和镀件材料溶解到镀液中,挂具和镀件带入了其它镀槽的镀液;应及时对挂具修理和清洗。（4）镀件掉入镀液中没有及时取出而形成的腐蚀产物;应防止镀件掉入镀槽,掉入的镀件应及时取出。（5）镀液添加剂在生产中在电极上被氧化。     

（Gd0．4Sm0．5Yb0．1）2Zr2O7陶瓷的合成与导热性能研究

以Gd2O3、Sm2O3、Yb2O3和ZrOCl2·8H2O为原料，采用化学共沉淀法合成了一种新型的多元稀土锆酸盐（Gd0．4Sm0．5Yb0.1）2Zr2O7陶瓷粉体，在1600℃无压烧结10h合成了致密的陶瓷块体。用X射线衍射仪（XRD）／及场发射扫描电镜（SEM）对粉体和块体的微观结构进行了表征，采用激光闪射法测试了块体的导热性能。结果表明，制备的多元稀土锆酸盐陶瓷粉体具有焦绿石结构，晶粒细小，陶瓷的热导率明显低于一元稀土锆酸盐Sm2Zr2O7的热导率。该研究结果显示（Gd0.4Sm0.5Yb0.1）2Zr2O7，多元稀土锆酸盐陶瓷有可能应用于热障涂层陶瓷层材料。     

Purification of Alkaline Earth Metals

The study demonstrates that alkaline earth metals can be sublimed or distilled to give metal of very high purity. The metallic impurities are the most easily separated although the other alkaline earth metals require a fractional sublimation. The interstitial elements 0, N and C can be reduced to very low levels if entrainment is prevented by subliming or distilling under a small torr pressure of an inert gas. Hydrogen transfers to the product in either distillation or sublimation and must be removed by vacuum traction from a Ta capsule. Alkaline earth metal purification by sublimation and distillation started in 1960 to supply pure Ca, Ba and Sr for phase equilibria studies and was expanded to provide high purity Ca for metallothermic preparation of very pure rare earth metals as described by Spedding et al.1 The objectives were to produce metals of the lowest possible interstitial solute concentration with a high yield and in a convenient form for handling in inert atmosphere gloveboxes. Enhance d process reliability with regard to product purity also eliminates expensive and time-consuming chemical analyses on each batch of metal.     

稀土金属提纯方法与研究进展

对各种提纯稀土金属方法的机理进行了阐述,包括真空熔炼、电解精炼、真空蒸馏/升华、熔盐萃取、区域熔炼、固态电迁移、电化学脱氧、外吸气剂法、等离子体熔炼(通氢气或通氩气)等。对研究现状和提纯效果进行了总结。杂质去除需采用多种手段结合,同时提升装备水平,以达到提高提纯效果、降低成本、缩短生产周期的目的。     

高纯金属镝的制备

为制备高纯度稀土金属Dy以适应高科技发展的需求,在钙热一次还原法生产的Dy-4,Dy-8的基础上,用中频感应炉进行二次精炼和真空蒸馏,并对工艺进行优化选择得出,二次精炼温度为1450℃,保温40min最适宜;真空蒸馏1500℃～1530℃,保温8h最佳。用此工艺所制备的金属Dy的纯度超过国标高纯度Dy-1和Dy-2的要求,接近国外高纯Dy的先进技术指标。     

高纯钴的制备

对目前高纯钴的制备方法进行了综述和评价。制备高纯钴的冶金工艺过程主要包括萃取法、膜分离法、离子交换法、电解法、区域熔炼法等，这些方法在除杂方面发挥着不同的作用。溶剂萃取法对大多数金属离子有很好的效果，但对Ni，Cu，Zn等金属离子的分离效果相对较差；膜分离法存在稳定性差、成本高的缺点；离子交换和萃取色层法对分离性质相近的元素有较好的效果，但存在容量低等问题；区域熔炼过程可以去除金属钴中的碱金属、碱土金属和气体杂质，并有利于生成纯度高、RRR值大的完整钴单晶。在总结上述各方法特点的基础上，提出了制备高纯钴的合理工艺。     

Dependence of the rare earth metal solubility in solid magnesium on its atomic number

The existence of the regular connection between the rare earth metal solubility in solid magnesium and its atomic number is shown. For the elements of the lanthanum row, the solubility values successively increase the atomic number, except for europium and ytterbium, which have an anomalous small solubility. In general, solubility increases in accordance with the decrease of the atomic radius of the rare earth metal as far as the difference between sizes of the rare earth metal and magnesium atoms becomes less there. Nevertheless, some solubility changes do not correspond to the rare earth atomic radius values.     

Current efficiency in electro-winning of lanthanum and cerium metals from molten chloride electrolytes

The objective of this study is to prepare lanthanum and cerium metals by fused salt electrolysis of their anhydrous chloride in molten media such as LiCl-KCl, NaCl-KCl, KCl, NaCl, and LiCl and to characterize the metal deposit by X-ray diffraction, energy dispersive X-ray fluorescence, and inductive coupled plasma-atomic emission spectroscopy. Deposit metal of purity more than 99 % was obtained in each of the experiments. The entire process starting from preparation of anhydrous lanthanum/cerium chloride to electrolysis yielding of metal deposits has been described. The effect of process parameters such as temperature, electrolyte composition, and current density on the current efficiency was studied. All these parameters were varied to get the highest current efficiency and metal yield. The major non-rare earth impurities with the deposit are found to be Fe, Cr, and Ni along with ～1×10-3 of total gaseous impurities.     

镧热还原氧化钐过程硅、铝杂质的行为探讨

对镧热还原氧化钐的反应产物镧渣,通过扫描电镜及X射线能谱仪对微区进行了显微观察和成分分析,结果发现:还原剂金属镧带入的杂质硅、铝在局部富集,并且在一定温度范围内与还原剂金属镧和还原产物金属钐生成同份熔化化合物,对镧的扩散还原和钐的扩散蒸发产生了一定的阻碍作用,影响了单炉次金属钐回收率的提高。分析讨论了杂质硅、铝在镧热还原氧化钐过程中的行为及局部富集的原因。     

Commercial production of rare earth metals by fused salt electrolysis

The commercial production of rare earth metals by fused salt electrolytic methods is described. These methods are used to make mischmetal, cerium, lanthanum, and didymium (Nd + Pr). The feed materials consist essentially of anhydrous chlorides of the metal to be produced, augmented by additions of nonrare earth salts to yield an electrolyte with satisfactory properties for reduction. The rare earths are derived either from monazite or from bastnasite ores. The anhydrous chlorides are manufactured from the hydrated chlorides by methods which minimize oxidation or hydrolysis. Alternatively, anhydrous chlorides may be used which result from the direct chlorination of rare earth ores by the Gold-schmidt process. These are particularly suitable for electrolysis due to their very low oxychloride content. Fluorides and oxides of the rare earths are produced by wet chemical methods to provide the relatively small quantities of these compounds now used for commercial fused salt electrolysis. Reduction cells in use today are constructed mainly from a) ceramics, b) graphite, or c) iron. The advantages and disadvantages of these types of cells are described together with the typical products which result from their use. Primary attention is given to production of mischmetal (mixed rare earth metal), which is the rare earth metal produced on the largest scale today. Brief reference is made also to production of cerium, lanthanum, and didymium (Nd + Pr) metal. Finally, a resume of the current uses of these metals is presented with reference to recent trends in the industrial applications of the rare earth metals.     

The pH effect for rare earth metals Nd, Pr and Y in aqueous solution dissolved Mg, Zn and Al

The pH variations of Mg, Zn and Al solutions to which had been added the rare earth metals Nd, Pr and Y were observed in 3.5 wt.% NaCl with respect to high energy mechanical ball milling effects. Mg was directly dissolved and exhibited a pH value of 10.5. On the other hand, Zn and Al needed to be saturated for a certain amount of time. The addition of rare earth metals played a role in increasing the pH with low reduction potentials. Additionally, mechanical ball milling provided high energy to Mg + x wt.% Zn + 0.5 wt.% Nd mixture by fracturing fragmentation of metals, which led to an increase in the pH when the mixture was immersed in 3.5 wt.% NaCl. The addition of Zn to Mg + 0.5 wt.% Nd caused a higher pH than when Mg + 0.5 wt.% Nd alone was added.