白光LED用新型红色荧光粉KCaY(MoO4)3:Eu3+的制备及发光性能

采用高温固相法制备了新型KCaY1-x(Mo04)3:Eux红色荧光粉.利用X射线衍射(XRD)、扫描电镜(SEM)和荧光光谱技术对粉体进行了结构、表面形貌和发光性能表征.结果表明:该系列荧光粉均为四方晶系的白钨矿结构,能够被近紫外光(394 nm)和蓝光(465 nm)有效激发,产生Eu3的5 D0→7 F2特征跃迁红光发射(613 nm).对这种荧光粉作后处理,可改善其表面形貌,并提高其发光强度.该系列荧光粉在394,465 nm的吸收与目前广泛应用的近紫外和蓝光LED芯片的输出波长相匹配.因此这种荧光粉是一种可能应用在白光LED上的红色荧光粉材料.     

Sm2O3改性对S2O2-8/ZrO2-SiO2固体超强酸催化剂性能的影响

硫酸促进型固体超强酸催化剂具有极强的酸性,制备简单,在酯化、烷基化、酰基化等有机反应中催化活性高,可重复使用,对设备腐蚀小,环境友好,是一类具有广阔应用前景的新型绿色催化材料,已成为固体超强酸研究的热点之一。然而,目前该类催化剂使用成本高、比表面小、含硫基团容易流失、稳定性差,阻碍了其在工业上的推广和应用。为了探索和改善其催化性能,近年来多组分氧化物的固体超强酸开始引起人们的关注。     

稀土(RE=Sm,Gd,Eu)乙二胺N,N-二(2-乙酰胺苯甲酸)二乙酸配合物合成、表征与性质

通过乙二胺四乙酸二酐(EDTAD)与邻氨基苯甲酸进行酰化反应,得到乙二胺N,N-二(2-乙酰胺苯甲酸)二乙酸配体(H4L),并分别与Sm、Gd和Eu稀土离子在乙醇-水溶液中反应得到系列稀土配合物.通过IR、摩尔电导率、UV、元素分析及热重-差热分析对配合物进行表征,得出配合物的化学组成为RE(HL)·3H2O(RE=Sm,Gd,Eu).IR表明,配体(H4L)形成配合物后出现了羧酸盐特有的反对称伸缩振动吸收峰vas,Coo-和对称伸缩振动吸收峰vs,Coo-,配体以羧酸根的形式与稀土离子配位.室温下测定了配合物的荧光激发光谱和发射光谱,Gd(HL)·3H2O和Sm(HL)·3H2O的荧光光谱中主要观察到配体强的发射峰,而配合物Eu(HL)·3H2O还显示Eu离子的特征发射光谱,在597 nm处5D0→7F1跃迁的发射峰最强.循环伏安法研究配合物的电化学性质表明配合物都表现出不可逆的氧化还原过程.     

Determination of transition and rare earth elements in low-alloy steels as chelates with 4-(2-Thiazolylazo)resorcinol by reversed-phase high performance liquid chromatography

4-(2-Thiazolylazo)resorcinol (TAR) is used as a chelating reagent in the reversed-phase HPLC separation and determination of transition and rare earth elements in low-alloy steels. A precolumn derivatization method is used, followed by separation on an octadecyl-bonded silica stationary phase with a sodium octane-1-sulphonate-tartaric acid mobile phase. The eluted metal chelates are detected by uv-visible spectrophotometry. The requirements for sample preparation, characterization of precolumn derivatization and the optimum conditions for the sensitive detection of metal ions after liquid chromatography (LC) separation are discussed. The influence of the pH of the chelating medium and the eluent, the concentration of TAR and the eluent were investigated. The results are compared with those of other methods such as atomic absorption spectrometry (AAS) and inductively coupled plasma atomic emission spectrometry (ICP-AES).     

还原-硅化法制备稀土硅化物（NdSi2，YSi2）纳米晶及其性能(英)

本文采用无水的氯化钕和氯化钇及硅粉作为起始原料，在高压釜中在650 ℃的温度条件下，通过还原-硅化途径成功地合成了硅化钕（NdSi₂）和硅化钇（YSi₂）。X射线衍射结果显示他们分别是四方相的二硅化钕和六方相的二硅化钇结构。透射电镜照片表明他们的平均粒径分别是40 nm和60 nm。样品的光致发光结果说明他们在波长分别为441 nm和366 nm处能发光。热重曲线显示他们在流动空气的介质中在550 ℃以下具有很好的抗氧化性。     

Molecular Rare‐Earth‐Metal Hydrides in Non‐Cyclopentadienyl Environments

Molecular hydrides of the rare‐earth metals play an important role as homogeneous catalysts and as counterparts of solid‐state interstitial hydrides. Structurally well‐characterized non‐metallocene‐type hydride complexes allow the study of elementary reactions that occur at rare‐earth‐metal centers and of catalytic reactions involving bonds between rare‐earth metals and hydrides. In addition to neutral hydrides, cationic derivatives have now become available.     

A Highly Triflated Rare‐Earth Ion in [Eu(O3SCF3)8]5−

The reaction of Eu₂O₃ with fuming nitric acid, trifluormethanesulfonic acid, and its anhydride in torch‐sealed glass ampoules at 120 °C gave the europium compound (NO)₅[Eu(O₃SCF₃)₈] (orthorhombic, Fddd, Z=16, a=1932.69(4), b=2878.44(7), c=2955.12(7) pm, V=16439.7(7) ų). The compound exhibits the [Eu(O₃SCF₃)₈]^5? anion showing for the first time a lanthanide ion that is exclusively coordinated by eight triflate anions. The anion has been further investigated by DFT calculations, which also allowed clear assignment of the vibrational spectra. Moreover, magnetochemical and luminescence measurements gave additional insight into the properties of this complex. The luminescence spectra revealed that the Eu³⁺ ions are in a pseudo D_4d symmetric environment.     

微波大功率稀土复合石榴石铁氧体的研究

报道了用稀土元素Gd,Dy和金属元素Al,Mn等按适当比例部分置换Y,Fe制备钇钆镝复合石榴石铁氧体((YGdDy)IG)的研制方案和实验结果。实验结果表明,该种材料除具有优良的旋磁特性外,还兼备承受高平均功率和高峰值功率的性能。其主要特性参数为:4πMs依实用需要可在48～96mT内选择,且具有甚高的温度稳定度:在0～160℃范围内Ms的温度系数αM≤2.8×10-4℃-1;电阻率ρ高达1013Ω·m,介电损耗tanδe≤4×10-4;居里温度TC≥500K;共振线宽ΔH=3.4～6.4kA·m-1;门阈场Hcrit适用于MW级脉冲功率。该种铁氧体可用作甚高频及微波低频段、超大功率的环行器和变极化器等微波器件。     

稀土发光和贮氢材料研究进展

本文结合我们自己的工作总结和概括了稀土发光材料和贮氢材料最近几年来的研究和应用新进展。     

水杨醛缩5-氨基水杨酸Schiff碱及其稀土配合物合成、表征和抑菌活性

水杨醛缩5-氨基水杨酸Schiff碱及其稀土配合物合成、表征和抑菌活性;水杨醛缩氨基水杨酸Schiff 碱;稀土配合物;合成;抑菌活性