K_2Ln(NO_3)_5·2H_2O(Ln=La,Ce,Pr,Nd,Sm)的晶体生长和热重-差热分析研究

本文生长出了K2Ln（NO3）5.2H2O（Ln=La；Ce；Pr；Nd；Sm）的单晶，并对其进行了晶体结构及差热-热重分析研究．结果表明，K2Ln（NO3）5.2H2O（Ln=La；Ce；Pr；Nd）的晶体属正交晶系，Fdd2空间群．首次生长出KPrN单晶并用直接法解出其晶体结构．解得KPrN的晶胞参数为：a=11．2210（10）,b=21．411（3），c=12．208（2）,Z=6；R=0．0240．对KLnN加热，则依次出现脱水、熔化、不可逆相变和NO的分解过程（K2Ce（NO3）5·2H2O除外）K2Ln（NO3）5·2H2O（Ln＝La；Nd；Sm）的NO分三步分解，K2Ln（NO3）5·2H。O（Ln=Ce；Pr）的NO分两步分解·KNO3和Ln（NO3）3·nH2O的混合物在225℃左右生成K2Ln（NO3）5

Synthesis, extraction and electronic structure of Ce@C-2n

In view of the growing interest in endohedral lanthanide fullerenes, Ce, as a typical +4 oxidation state lanthanide element, has been systematically studied. The synthesis, extraction and electronic structure of Ce@C-2n are investigated. Soot containing Ce@C-2n was synthesized in high yield by carbonizing CeO2-containing graphite rods and are back-burning the CeC2-enriched cathode deposit in a DC are plasma apparatus. Ce@C-2n, dominated by Ce@C-82, can be efficiently extracted from the insoluble part of the soot after toluene Soxhlet extraction by pyridine at high temperature and high pressure in a closed vessel. About 60% Ce@C-2n (2n = 82,80,78,76) and 35% Ce@C-82 can be enriched in the pyridine extract. This fact is identified by desorption electron impact mass spectrometry (DEI MS). The electronic structure of Ce@C-2n is analyzed by using X-ray photoemission spectroscopy (XPS) of pyridine-free film. It is suggested that the encapsulated Ce atom is in a charge state close to +3 and was effectively protected from reaction with water and oxygen by the enclosing fullerene cage. Unlike theoretical expectation, the electronic state of Ce@C-82 is formally described as Ce+3@C-82(3-). (C) 1997 Elsevier Science Ltd.

Synthesis and luminescence characteristics of LiMgAlF6:Ln(3+) (Ln = Ce, Eu, Tb)

By solid state reaction, LiMgAlF6 and LiMgAlF6:Ln(3+) are synthetized with the ratio 120/100/110 of LiF/MgF2/AlF3, at 1008 K, in high-purity Ar stream. Their crystal structure which belongs to hexagonal system are determined by X-Ray-Diffraction (XRD). Luminescence characteristics of Ce3+, Eu3+, Tb3+ and sensitization of Ce3+ to Tb3+ in LiMgAlF6 are studied. It is shown that the sensitization of Ce3+ to Tb3+ is efficient and a bright green emission is observed.

Gas phase derivatization of endohedral metallofullerenes R@C-82 and R-2@C-80 (R = Nd, Ce)

Endohedral metallofullerenes Ce@C-82, Ce-2@C-80, Nd@C-82 and Nd-2@C-80 undergo gas phase ion/molecule reactions with the ion system from self-chemical ionization of vinyl acetate, and exohedral derivatives are thus generated, A new heterocycle is formed from metallofullerenes and a C2H3O+ cation, Endohedral metallofullerenes show much higher reactivities than empty fullerenes during the association and the charge and proton transfer processes, The strong electron-donating character of endohedral metallofullerenes is due to their unique super-atom-like electronic structures. (C) 1997 by John Wiley & Sons, Ltd.

CaAl_3BO_7:RE(RE=Ce,Gd,Tb)中稀土离子的光谱特性

采用固相反应法合成了ＣａＡｌ３ＢＯ７ＲＥ（ＲＥ＝Ｃｅ，Ｇｄ，Ｔｂ），研究了Ｃｅ３＋，Ｇｄ３＋和Ｔｂ３＋的光谱特性．发现铈离子周围存在较强的晶场，使基态的４ｆ能级劈裂较大，从而导致铈离子的特征发射峰重叠较大；Ｃｅ３＋的５ｄ能级明显低于Ｇｄ３＋的６Ｉ、６Ｐ能级；Ｃｅ３＋和Ｔｂ３＋之间存在有效的能量传递

CeO_2纳米粒子形成过程中Ce的价态变化

用溶胶凝胶法制备了ＣｅＯ２纳米粒子，ＸＲＤ分析表明，所合成的ＣｅＯ２纳米粒子均为立方晶系，空间群为Ｏ５ｈＦｍ３ｍ。ＴＥＭ分析表明，ＣｅＯ２粒子为球形。研究了ＣｅＯ２纳米粒子形成过程中Ｃｅ价态的变化与性质，发现干凝胶中Ｃｅ３＋和Ｃｅ４＋共存；当焙烧温度低于２３０℃时，随焙烧温度的升高，Ｃｅ３＋含量逐渐降低，Ｃｅ４＋含量逐渐增高，即Ｃｅ３＋缓慢地氧化成Ｃｅ４＋；当焙烧温度高于２３０℃时，Ｃｅ３＋快速氧化成Ｃｅ４＋，至２５０℃时Ｃｅ３＋完全氧化成Ｃｅ４＋。焙烧温度低于２５０℃处理的样品中Ｏ１ｓ的光电子能谱明显不同，反映出样品晶格结构的变化。

Ce∶SrAlF_5晶体生长及其光谱特性

Ｃｅ∶ＳｒＡｌＦ５晶体生长及其光谱特性张吉林（辽阳石油化工专科学校，辽阳１１１００３）洪广言（中国科学院长春应用化学研究所，长春１３００２２）ＣｒｙｓｔａｌＧｒｏｗｔｈａｎｄＳｐｅｃｔｒｏｓｃｏｐｉｃＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＣｅ：ＳｒＡｌＦ...

非线性光学新材料K_2Ln(NO_3)_5.2H_2O(Ln=La,Ce,Pr,Nd,Sm)的晶体生长、结构和表征

非线性光学新材料Ｋ２Ｌｎ（ＮＯ３）５·２Ｈ２Ｏ（Ｌｎ＝Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ，Ｓｍ）的晶体生长、结构和表征董文庭张洪杰苏锵（中国科学院长春应用化学研究所稀土化学与物理开放实验室，长春１３００２２）Ｇｒｏｗｔｈ，ＳｔｒｕｃｔｕｒｅａｎｄＣｈａｒａｃｔ...

Relationship between the dissolution behaviours and current efficiencies of La, Ce, Pr and Nd in their chloride molten salts

The dissolution behaviours of La and Nd in their chloride molten salts were studied by means of the see-through cell, electrochemical weak polarization and quantum chemistry (extended Huckel molecular orbital). The reasons for the low current efficiencies of rare earth metals and the difference between La and Nd in their own chloride electrolytes on the basis of the solubility, rate of dissolution, and existing state of the metals dissolved as well as the structure of the melts, are discussed.

Ce~（3＋），Tb~（3＋）在Al_4B_2O_9和Al_（18）B_4O_（33）基质中的发光

采用固相反应法在Ａｌ２Ｏ３－Ｂ２Ｏ３体系中合成了Ａｌ４Ｂ２Ｏ９和Ａｌ１８Ｂ４Ｏ３３两个相关化合物，测定了在两种基质中Ｃｅ３＋，Ｔｂ３＋和Ｃｅ３＋－Ｔｂ３＋的光谱，观察到在两种基质中Ｃｅ３＋的光谱相似，Ｃｅ３＋的发射峰位置在Ａｌ１８Ｂ４Ｏ３３中比Ａｌ４Ｂ２Ｏ９稍有红移。实验表明，Ａｌ１８Ｂ４Ｏ３３将是一种好的发光基质

光折变Ce∶Nd∶LiNbO3晶体用于实时光学图象处理

Ｃｅ：Ｎｄ：ＬｉＮｂＯ３晶体具有优良的光折变性能，它作为全息记录介质，用于实现了光学图象微分和全息关联存储。

Ce~（3＋）在钙钛矿型KMF_3（M＝Mg、Ca、Sr、Ba）基质中的发光特性

采用高温固相反应法，在Ａｒ气氛中合成了ＫＭＦ３（Ｍ＝Ｍｇ、Ｃａ、Ｓｒ、Ｂａ）基质化合物和掺杂Ｃｅ３＋的磷光体。经Ｘ射线衍射分析确定，ＫＭｇＦ３和ＫＣａＦ３属于立方晶系、钙钛矿型结构，ＫＳｒＦ３和ＫＢａＦ３具有类似的结构。测定了ＫＭＦ３∶Ｃｅ３＋的发光光谱，观察到与其结构对应的分为二种不同的光谱结构，讨论了Ｃｅ３＋的取代格位

CHARACTERIZATION OF OXIDES AND HALOGENIDES OF CERIUM BY ESCA .2. AUGER PEAKS OF CE-M5N45N45

The larger chemical shift of cerium compounds was discoveried. The chemical states of the cerium compounds were identified by the chemical shifts of Auger energy. The changes in Anger energy and parameters are principally due to the changes in extra-atomic relaxation or polarization energy. The increase of the polarizable properties in anions of cerium compounds corresponds to the increase of Auger energy and parameter. The Auger parameter can be measured more accurately. Ce(CF3COO)(x)Cl-3-x was also studied by ESCA. It is shown that the electron density at cerium atom increases with the increase of x, while the electron density at oxygen atom decreases.

掺Ce~（3＋）、Gd~（3＋）、Tb~（3＋）的CaLaB_7O_（13）的光

采用固相反应法合成了接Ｃｅ３＋、Ｇｄ３＋、Ｔｂ３＋的ＣａＬａＢ７Ｏ１３，并测定了它们的光谱．在Ｃｅ３＋的光谱中发现文献中尚未报导的３１７ｎｍ激发峰和２９３ｎｍ发射峰．２９３发射属于不常见的５ｄ能带中次最低能级向基态的跃迁，并随着Ｃｅ３＋离子浓度增加而变弱，当掺杂浓度大于０．１ｍｏｌ时，２９３ｎｍ发射峰消失.