R12Pt7In (R=Ce, Pr, Nd, Gd, Ho)—new derivatives of the Gd3Ga2-type

A new compound Ce₁₂Pt₇In was synthesized and its crystal structure at 300 K has been determined from single crystal X-ray data. It is tetragonal, space group I4/mcm, Z=4, with the lattice parameters: a=12.102(1) Å and c=14.542(2) Å, wR2=0.1102, 842 F² values, 33 variable parameters. The structure of Ce₁₂Pt₇In is a fully ordered ternary derivative of the Gd₃Ga₂-type. Isostructural compounds has been found to form with Pr (a=11.976(1) Å, c=14.478(2) Å), Nd (a=11.901(1) Å, c=14.471(2) Å), Gd (a=11.601(3) Å, c=14.472(4) Å), and Ho (a=11.369(1) Å, c=14.462(2) Å). Magnetic properties of Ce₁₂Pt₇In, Pr₁₂Pt₇In and Nd₁₂Pt₇In were studied down to 1.7 K. All three ternaries order magnetically at low temperatures with complex spin arrangements. The electrical resistivity of Ce₁₂Pt₇In and Nd₁₂Pt₇In is characteristic of rare-earth intermetallics.     

Thermal decomposition of 4,4′-dipyridyl complexes of light rare-earth thiocyanates in air atmosphere

The thermal decompositions of Ln(NCS)₃(4-dipy)₂·5H₂O were studied, whereLn=La, Pr, Nd, Sm, Eu and Y, and 4-dipy=4,4′-dipyridyl. The compounds are first dehydrated. During the thermal decomposition of Ln(NCS)₃(4-dipy)₂, deamination takes place. The transient products decompose with the formation of Ln₂O₂SO₄. The energies of activation for the first step of dehydration of the La, Pr, Nd, Sm and Eu complexes were determined.

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Zusammenfassung Es wurde die thermische Zersetzung von Ln(NCS)₃(4-dipy)₂.5H₂O mitLn=La, Pr, Nd, Sm, Eu, Y und 4-dipy=4,4′-Dipyridyl untersucht. Die Verbindungen werden zuerst dehydratiert. Bei der thermischen Zersetzung von Ln(NCS)₃(4-dipy)₂ findet eine Desaminierung statt. Die übergangsprodukte zersetzen sich unter Bildung von Ln₂O₂SO₄. Die Aktivierungsenergie für den ersten Schritt der Dehydratation der La-, Pr-, Nd-, Sm- und Eu-Komplexe wurde ermittelt.

     

稀土离子谱带强度的Judd-Ofelt理论的研究

本文对Judd-Ofelt光谱分析理论（J-O理论）的发展和应用进行了综述．J—O理论用于分析固体中的稀土离子的吸收、发射光谱，可计算它们的跃迁几率、谱线强度、能级寿命、发射截面等．     

稀土金属有机配合物化学60年

60年来稀土金属有机配合物化学取得重要发展. 辅助配体从环戊二烯基,五甲基环戊二烯基,茚基发展到各种非茂配体,如双酚,β-二亚胺,胍基,脒基等. 配合物的种类从简单的三茂稀土配合物发展到各种形式的二茂稀土配合物和单茂稀土配合物. 非茂配体的应用不仅拓展了稀土金属有机配合物的结构种类,还极大推动稀土金属有机配合物在高分子和有机合成中的应用. 稀土金属有机配合物可有效催化烯烃均聚与共聚,共轭双烯烃以及极性单体的选择性聚合. 稀土金属有机配合物还能催化氢化,氢胺化和膦氢化等重要有机反应. 本文对稀土金属有机配合物化学过去60年的发展进行综述.     

稀土上转换纳米发光材料研究进展

上转换纳米发光材料(UCNPs)是一种能在长波长光激发下发出短波长光的发光材料.在较多的研究中UCNPs在980 nm红外光激发下,能发出不同颜色的可见光,可以显著提高信噪比,所以UCNPs在三维立体显示、上转换激光器、红外探测、防伪识别、生物检测等诸多领域都具有广阔的应用前景.从稀土上转换纳米发光材料的基质和稀土离子及其光学性能方面概述了近几年稀土上转换纳米发光材料的研究进展.     

The Long-Periodic Loop-Branched Chain Structure of the Oxonitridophosphate La21P40O46N57, Elucidated by a Combination of TEM and Microfocused Synchrotron Radiation

The lanthanum oxonitridophosphate La₂₁P₄₀O₄₆N₅₇ was synthesized by high-pressure metathesis from partially hydrolysed LiPN₂ and LaCl₃ at 750–950 °C and 7–9 GPa. The combination of transmission electron microscopy (TEM) and diffraction using microfocused synchrotron radiation revealed a monoclinic crystal structure (space group P2₁/n, a=14.042(4), b=7.084(3), c=41.404(10) Å, β=97.73(3)° and Z=2), which is characterized by loop-branched 21 member single chains of P(O,N)₄ tetrahedra that extend along [2 0 1]. These chains are related to the loop-branched dreier single chains with dreier-ring loops in stillwellite (CeBSiO₅). In La₂₁P₄₀O₄₆N₅₇, these chains are characterized by a complex long-periodic conformation and exhibit disorder that involves La/N and P split positions. This is an extraordinarily long periodicity with respect to branched single chains of tetrahedra. La₂₁P₄₀O₄₆N₅₇ constitutes the first rare-earth oxonitridophosphate exhibiting a chain structure. Single-crystal data are consistent with electron and powder X-ray diffraction.     

Theoretical and experimental study on rare-eath element-doped silicon single-mode fiber laser with two different structures of resonators

Abstract: Laser resonator is very important in the study and fabrication of lasers. The work conditions and work parameters of rare-earth element-doped optical fiber lasers with two different structures of laser resonators, i. e., the fiber ring resonator and Fabry-Perot resonator are studied. The fineness, laser resonant conditions, laser oscillation conditions and threshold inversion of these two different cavity are deduced. A series of experiments are also given. The result is very valuable to evaluate the output of optical fiber laser and can be a foundation of device fabrication. The Nd~(3 )-doped silica single-mode fiber laser pumped by Ar~ laser with a low threshold of 1.02 mW and a maximum output of more than 1 mW are presented in this paper.     

Preparation of Optical Cores of Silica Optical Fibers by the Sol-Gel Method

Preforms for drawing silica optical fibers have been fabricated by using the MCVD method for the preparation of the optical claddings and the sol-gel method for the preparation of the optical cores consisting of TiO₂−SiO₂ or RE³⁺−Al₂O₃−P₂O₅−SiO₂ (RE=Er, Yb) glasses. A novel method has been developed for depositing thin gel layers on the inner silica tube wall, under rotation of the tube inclined at a small angle to the horizontal. The gel layers have been deposited from sols prepared by mixing Si(OC₂H₅)₄, POCl₃, Ti(n-OC₄H₉)₄, AlCl₃, ErCl₃, YbCl₃ H₂O, C₂H₅OH and HCl. The gel layers deposited using these sols on the inner tube wall were heat-treated in a flow of CCl₄ or POCl₃ with O₂ at temperatures of from 800° to 1400°C. After collapsing the composite tube into a preform, an optical fiber has been drawn. The refractive-index profiles of the preforms and the attenuation spectra of the drawn fibers are shown, as well as some results on the lasing characteristics of Yb³⁺ sensitized, Er³⁺ doped fibers.     

共掺杂效应对Y2O3∶Eu^3＋和Gd2O3∶Eu^3＋发光影响的理论研究

通过在Y2O3∶Eu3 和Gd2O3∶Eu3 发光材料中掺入Li ,Mg2 ,Al3 等离子能有效地提高材料的发光强度,根据分子动力学和密度泛函计算的结果,认为这些离子多倾向于形成C2格位附近的间隙缺陷对,导致部分Y(Gd)—O的键长增加,提高了材料的量子效率的同时使得激发峰位出现红移,是引起材料发光增强的一个原因。