稀土氧化物/MC尼龙纳米复合材料的制备及性能研究

用原位分散聚合法制备了一系列稀土氧化物(La2O3、Sm2O3、Nd2O3、Gd2O3、Dy2O3)/MC尼龙纳米复合材料,用SEM观察了稀土氧化物纳米粒子在MC尼龙基体中的分散情况,用XRD研究了复合材料的晶体结构,并对复合材料的力学性能进行了表征.研究结果表明:用原位分散聚合法制备稀土氧化物/MC尼龙纳米复合材料是可行的,稀土氧化物纳米粒子均匀分散在MC尼龙基体中,团聚情况很少;稀土纳米氧化物没有改变MC尼龙的结晶形态,但使其晶格尺寸发生了一定程度的改变;稀土纳米氧化物可显著改善MC尼龙的力学性能,对MC尼龙同时具有增强和增韧的双重效果.     

稀土氧化物添加剂对Al2O3等离子喷涂层的影响

在Al2O3陶瓷材料中添加不同含量的稀土氧化物添加剂，探讨了稀土氧化物对等离子喷涂Al2O3涂层组织、结合强度和抗热冲击性的影响。研究结果表明，加入适量稀土氧化物添加剂后可降低涂层中的孔隙率和气孔尺寸，减少涂层内应力在气孔边缘的应力集中，提高了Al2O3涂层的结合强度和抗热冲击性能。     

日媒认为朝鲜发现最大稀土矿将打破中国垄断

正日媒称,一家设在英国的私募股权公司表示,该公司已经在朝鲜发现了世界上最大的稀土氧化物矿床。据日本《外交学者》杂志网站1月22日报道,2013年12月,这家名为SRE矿业有限公司的英国公司公布了其对朝鲜稀土氧化物储量的评估结果。最引人注目的是,该公司声称估计定州矿含有2.16亿吨稀土氧化物,包括轻稀土元素、重稀土元素和稀土矿物。根据美国之音电台的报道,这将令目前全     

La2O3、Nd2O3、Y2O3对高岭石高温相变动力学的影响

利用综合热分析技术、X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)和扫描电镜(SEM)研究了La_2O_3、Nd_2O_3、Y_2O_3对高岭石高温条件下转变成莫来石过程的作用,并采用Kissinger方程、Ozawa方程以及JMA修正方程(Ⅰ)和(Ⅱ)分析了La_2O_3、Nd_2O_3、Y_2O_3对高岭石高温相变动力学的影响。结果表明:3种稀土氧化物的掺入对高岭石的相变动力学参数产生了影响,相变活化能和频率因子与未掺入稀土氧化物的高岭石相比有所降低,析晶方式则未发生变化,均属于体积晶化。对比掺入3种稀土氧化物的高岭石相变活化能和频率因子可以看出,Y_2O_3对于高岭石高温条件下相变的促进作用最为明显,相变活化能最低。稀土氧化物对于高岭石高温相变产物影响不大,主晶相为莫来石相,次晶相为方石英相,但稀土氧化物的掺入使得方石英相的结晶度明显提高。     

稀土难熔金属电子发射材料的研究

介绍了两种阴极,即稀土钼金属陶瓷次级发射材料及钪钨基扩散阴极。研究结果表明,稀土钼金属陶瓷阴极的最大次级发射系数可达6.5,与单元稀土氧化物掺杂的钼阴极相比,复合稀土氧化物-钼具有更高的次级发射系数,主要是由于复合氧化物在高温、真空条件下失氧速度小于单元稀土氧化物,相对于单元稀土氧化物具有较低的缺陷浓度,使缺陷对二次电子的散射作用减弱,从而有利于阴极的发射。钪钨基扩散阴极具有优异的热发射性能,900℃下阴极的发射电流密度达87A/cm~2,为普通钪酸盐阴极的3倍。活性元素Ba、Sc和O在阴极激活过程中同时向表面扩散,在阴极表面建立均匀分布的Ba、Sc和O活性层,促进了阴极的发射。     

稀土氧化物掺杂对氧化铝陶瓷力学性能和摩擦磨损性能的影响

研究氧化铝陶瓷的摩擦磨损特性随不同稀土氧化物掺杂的变化规律。方法制备不同稀土氧化物掺杂的氧化铝陶瓷样品,采用球-盘磨损方法进行摩擦磨损实验。分析掺杂后氧化铝陶瓷磨损前后的形貌、物相组成及元素组成,测试掺杂后氧化铝陶瓷相对密度和显微硬度。结果表明,掺杂后氧化铝陶瓷主要由α-Al_2O_3相组成,Y_2O_3和CeO_2掺量的逐渐增加有相应复合氧化物次晶相形成。不同稀土氧化物及添加量对氧化铝陶瓷的致密化和力学性能出现不同的影响,就晶粒尺寸而言,3种稀土氧化物掺量为0.5%时,晶粒最细;就致密化而言,添加Y_2O_3和CeO_2的陶瓷最优掺量为0.5%,添加La_2O_3的陶瓷最优掺量为1.5%;就硬度而言,添加Y_2O_3和CeO_2的氧化铝陶瓷最优掺量为1.5%,添加La_2O_3的氧化铝陶瓷最优掺量为0.5%。在干摩擦条件下,3种稀土氧化物掺杂后的试样磨损体积都在添加量为0.5%时达到最小值,氧化铝陶瓷磨损失重随着添加量的增加而变大。掺量为0.5%时,3种稀土氧化物掺杂的陶瓷均呈现较好的耐磨性能,其磨损机制以磨粒磨损为主。     

铈基稀土催化材料在大气污染治理中的研究进展

稀土氧化物,尤其是镧、铈等轻稀土元素的氧化物,被广泛应用于催化领域。围绕以CeO_2为代表的稀土催化材料在大气污染治理中的作用进行综述,并详细介绍了铈基稀土催化材料在机动车尾气净化、烟气脱硝、挥发性有机污染物催化燃烧等领域的最新研究进展。在汽油车尾气净化方面,如何进一步提高CeO_2基复合氧化物自身的稳定性,同时提高活性金属的利用效率、延长催化剂使用寿命是研究重点;在柴油车氮氧化物和颗粒物的排放控制方面,通过成分调控,利用稀土氧化物特别是CeO_2提高催化剂的低温活性、抗中毒性和水热稳定性等是研究热点;在固定源烟气脱硝方面,稀土氧化物尤其是氧化铈基脱硝催化剂具有高效、无毒、无二次污染等特点,可逐步替代高毒的钒钛系,实现环境友好;在挥发性有机物催化燃烧方面,CeO_2催化材料也已被实验证明具有良好的催化氧化能力。旨在为促进本领域的研究者更清楚地了解铈基稀土催化材料在大气污染治理中所发挥的作用及应用潜力,同时为科学地设计和应用下一代高性能催化材料提供参考。     

一维纳米稀土氧化物的研究进展

概述了国内外在一维纳米稀土氧化物(纳米管、纳米棒、纳米线)方面的研究现状,介绍了硬模板法、软模板法、水热法、超声法和微乳液法制备一维纳米稀土氧化物的工艺方法和机理,并对这些方法的优缺点进行了比较,指出了当前一维纳米稀土氧化物合成中存在的不足,并对一维稀土纳米氧化物的应用作了展望.     

纳米管稀土氧化物的制备及应用

稀土氧化物具有其独特的光、电等化学性质,在催化、发光、磁性等方面有很大的应用前景。如果将稀土氧化物制备成具有低的维数和高的比表面积的一维纳米管状,有可能增强其各方面的性能,它的开发和应用前景十分迷人。综述了稀土氧化物纳米管的制备方法,并介绍了稀土氧化物纳米管在催化、发光和磁性方面应用的进展,最后论述了还需要研究的问题和方向。     

稀土氧化物对氧化反应结合碳化硅陶瓷性能的影响

利用氧化反应结合工艺,从物相组成、氧化行为、致密化、力学性能和显微结构几个方面研究了将稀土氧化物(Y2O3、La2O3和CeO2)添加到SiC和Al2O3混合物中对SiC陶瓷的影响.结果表明,稀土氧化物的添加有利于氧化反应结合SiC陶瓷中莫来石相生成,使莫来石化温度下降了大约100℃;同时,稀土氧化物的添加不仅降低了反应结合SiC陶瓷的气孔率,还使其力学性能明显得到提高;在1300℃、保温2h烧结,4.5%-CeO2(质量分数)掺杂样品的气孔率下降到5%,抗弯强度达到150MPa.     

Novel Bimorphological Anisotropic Bulk Nanocomposite Materials with High Energy Products

Nanostructuring of magnetically hard and soft materials is fascinating for exploring next‐generation ultrastrong permanent magnets with less expensive rare‐earth elements. However, the resulting hard/soft nanocomposites often exhibit random crystallographic orientations and monomorphological equiaxed grains, leading to inferior magnetic performances compared to corresponding pure rare‐earth magnets. This study describes the first fabrication of a novel bimorphological anisotropic bulk nanocomposite using a multistep deformation approach, which consists of oriented hard‐phase SmCo rod‐shaped grains and soft‐phase Fe(Co) equiaxed grains with a high fraction (≈28 wt%) and small size (≈10 nm). The nanocomposite exhibits a record‐high energy product (28 MGOe) for this class of bulk materials with less rare‐earth elements and outperforms, for the first time, the corresponding pure rare‐earth magnet with 58% enhancement in energy product. These findings open up the door to moving from a pure permanent‐magnet system to a stronger nanocomposite system at lower costs.     

稀土发光材料燃烧合成的研究进展

在对稀土发光材料各主要合成方法进行了简单对比的基础上,介绍了燃烧合成技术及其快速、节能、操作简便等特点,介绍了燃烧合成技术在稀土发光材料合成中的应用现状及存在的主要问题,并展望了今后的发展前景.     

稀土配合物杂化材料的制备与性能研究

综述了近年来稀土配合物杂化材料的制备和性能．按基质的不同，稀土配合物杂化材料可分为稀土配合物，无机杂化材料，稀土配合物，有机杂化材料以及稀土配合物，混合基质杂化材料。本文对以上3种杂化材料的优缺点进行了较为详细的分析，并提出一步法制备稀土配合物杂化材料，以简化合戍步骤，提高稀土配合物在基质分布的均匀性，因而该方法有望戍为制备稀土配合物杂化材料的一个重要发展方向。     

Optical Properties of Functional Hybrid Organic–Inorganic Nanocomposites

Functional hybrids are nanocomposite materials lying at the interface of organic and inorganic realms, whose high versatility offers a wide range of possibilities to elaborate tailor‐made materials in terms of chemical and physical properties. Because they present several advantages for designing materials for optical applications (versatile and relatively facile chemistry, easy shaping and patterning, materials having good mechanical integrity and excellent optical quality), numerous silica or/and siloxane based hybrid organic–inorganic materials have been developed in the past few years. The most striking examples of functional hybrids exhibiting emission properties (solid‐state dye lasers, rare‐earth doped hybrids, electroluminescent devices), absorption properties (photochromic), nonlinear optical (NLO) properties (second‐order NLO properties, photochemical hole burning (PHB), photorefractivity), and sensing are summarized in this review.     

稀土发光材料的研究与展望

简要介绍了稀土发光材料的发光原理和八种制备方法，包括传统的高温固相反应法溶胶-凝胶法、水热合成法、低温燃烧合成法、化学沉淀法、微波辐射法、电弧法、CO2激光加热气相沉积合成法，总结了每种制备方法的优缺点，并对稀土发光材料的应用和发展前景进行了展望。     

一种胶版防伪油墨稀土发光材料制备的研究及应用

目的 制备吡啶二甲酸铕的稀土配合物,将其加入胶版油墨中,并对荧光性能进行检测和分析。方法 以稀土材料Eu盐为主要原料,在一定条件下与2,6-吡啶二甲酸反应形成一种光致发光的稀土配合物,并通过红外光谱和荧光光谱对物质结构进行表征。将合成的稀土配合物添加到白色胶印油墨中,通过印刷适性仪将油墨打印在纸张上。结果 通过荧光检测确定了该物质的主要激发波长为365 nm,发射波长为617 nm;在紫外灯照射下,加入质量分数为3%~4%发光材料的油墨所打印图案的油墨颜色接近于稀土材料的荧光颜色;在D65光源下,该油墨的色度与之前相比变化不大,且可以在加网的条件下完成印刷。结论 稀土发光材料在胶印油墨中发光性稳定,且稀土材料荧光体在油墨中可发光,实现了稀土发光油墨对有机荧光油墨的替代,有利于环境的保护。     

Study on preparation and characterization of MOF based lanthanide doped luminescent coordination polymers

Coordination polymers (metal–organic frameworks or MOFs) offer the opportunity for fine-tuning the luminescence behavior because of the possibility to entrap in the network pores molecules that can influence the lanthanide (Ln) emission. In this study, Zn (II) and polycarboxylate based MOFs were first pre-formed by solvothermal method, then considered as host-matrix for in situ doping of low-input concentration of Eu³⁺ and Tb³⁺ (two most commonly used lanthanides in life science assays), and afterwards lanthanide doped luminescent materials were synthesized. Different characterizations (X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive Spectroscopy (EDS)) were carried out to confirm accordingly MOF's crystallinity, the structure and chemical composition. The study on luminescent properties of the material has revealed an efficient energy transfer from the ligand excited states to the Eu³⁺ and Tb³⁺ f-excited states. With quite low input concentrations (8–15%) of doped rare earth ions, these complexes displayed intense emissions at room temperature and proved to be good candidates for red and green emitter luminescent materials. Generally, this design concept can be extended for the preparation of other rare earth coordination polymers.     

Brannerite,UTi<Subscript>2</Subscript>O<Subscript>6</Subscript>: Crystal chemistry,synthesis, properties,and use for actinide waste immobilization

The host materials suggested for immobilization of actinide waste of military or civil origin often contain the secondary (U,Pu)Ti2O6 phase of brannerite structure. For example, the materials for incorporation of excess plutonium, mainly consisting of pyrochlore, contain up to 30% brannerite. This is a usual phase in titanate host materials for isolating spent nuclear fuel (SNF) and products of its reprocessing, including waste from production of ^99mТс for medical purposes and other kinds of waste with high U and Pu content. Despite simple ideal stoichiometry, brannerite can contain large amounts of rare earths. This feature is due to the presence of uranium not only in the 4+ oxidation state, but also in the 5+ and 6+ states, which favors the exchange of rare earth elements (REE), e.g., in accordance with the scheme 2U⁴⁺ ? U⁵⁺ + REE³⁺. The REE amount in brannerite reaches 0.5–0.7 atom per formula unit. Therefore, brannerite is of interest as a host material for the rare earth–actinide fraction of high-level waste (HLW). To evaluate the prospects for such use of brannerite, data on the radiation resistance of brannerite and its behavior in aqueous solutions are analyzed. In these properties, brannerite is inferior to pyrochlore and zirconolite. The rate of actinide leaching from brannerite is higher by an order of magnitude than from these phases, but lower by 3–4 orders of magnitude than from glass host materials. Natural brannerite is stable in media with weakly alkaline and reducing waters. Therefore, brannerite seems suitable for immobilization of rare earth–actinide waste. This host material can be synthesized by sintering or cold crucible induction melting followed by crystallization.     

镁基储氢复合材料的研究进展

综述了镁基储氢复合材料开发和研究的最新进展，重点介绍了稀土／镁基储氢复合材料和镍／镁基储氢复合材料的主要种类、吸放氢性能和相关的制备工艺，简要分析了钛、铁、钒、锆／镁基储氢材料的研究现状和存在的问题，讨论了镁基储氢复合材料在储氢电极材料方面的应用前景。     

Application of Rare Earths in Thermal Barrier Coating Materials

Rare earths are a series of minerals with special properties that make them essential for applications including miniaturized electronics, computer hard disks, display panels, missile guidance, pollution controlling catalysts, H2-storage and other advanced materials. The use of thermal barrier coatings （TBCs） has the potential to extend the working temperature and the life of a gas turbine by providing a layer of thermal insulation between the metallic substrate and the hot gas. Yttria （Y203）, as one of the most important rare earth oxides, has already been used in the typical TBC material YSZ （yttria stabilized zirconia）. In the development of the TBC materials, especially in the latest ten years, rare earths have been found to be more and more important. All the new candidates of TBC materials contain a large quantity of rare earths, such as R2Zr207 （R=La, Ce, Nd, Gd）, CeO2-YSZ, RMeAI11019 （R=La, Nd; Me=Mg, Ca, Sr） and LAP04. The concept of double-ceramic- layer coatings based on the rare earth materials and YSZ is effective for the improvement of the thermal shock life of TBCs at high temperature.