稀土离子掺杂氟化物激光晶体研究进展

稀土离子掺杂氟化物晶体具有宽透光波段高透过率、低声子能量、长荧光寿命、负热光系数等优良特性,可以产生从紫外到中红外波段激光,是一类重要的激光增益介质。本文综述了本团队在稀土离子掺杂LiLuF₄、LiYF₄、BaY₂F₈、LaF₃、PbF₂、CeF₃等氟化物晶体生长、光学和激光性能等方面的研究进展,总结了稀土离子共掺敏化、退激活、能级耦合调控以及多离子发光等方面的研究工作,展望了稀土离子掺杂氟化物激光晶体的研究发展趋势。     

Preparation and Crystal Structure of a Rare-earth Salt Based on the Decavanadate (V10O286-):[Y(H2O)8]2[V10O28]·9H2O

The salt, [Y(H2O)8]2[V10O28]·9H2O, contains two discrete water-groups coordinated Y(III) cations, an isopoly complex ion, decavanadate (V10O286-) and nine additional water molecules, which are combined together by static electric forces and hydrogen bonds. The Y3+ is eight-coor- dinated with a square antiprism geometry. The single-crystal X-ray analysis reveals that the crystal crystallizes in triclinic, space group P with a = 9.1454 (18), b = 10.007(2), c = 12.772(3)(A),α = 68.86(3), β = 77.50(3),γ = 89.23(3)°, V = 1061.7(4)(A)3 and Z = 1.     

氮化硅（Si3N4）—稀土氧化物陶瓷的超高压烧结研究

在5～7GPa,600～1800℃的压力-温度范围内对组份为氮化硅-稀土氧化物微粉混合体(3Si_3N,+0.5La_2O_3+0.5Pr_6O_(11)(mol.％))的烧结产物进行了研究。所得结果表明其成相规律与Sialon体系在高温高压下烧结时不同。在直到5GPa的高压力下,α-Si_3N_4表现出相当高的稳定性,并不转变成β相。当烧结温度低于1600℃时,烧结体仍然由以α-Si_3N_4为基础的固溶体及稀土氧化物组成,而后者则表现出一系列相变化。当压力超过6GPa、温度高于1600℃时,物料烧结成一个新的单相高压结构ReSi_3O_2N_4。其衍射数据可以用一个正交点阵来拟合。其晶格参数为:α=1.2983nm,b=0.8140nm,c=0.4285nm。     

Magnetic and transport properties of some light rare earth tungstates

Measurements relating to molar magnetic susceptibility, dc electrical conductivity and thermoelectric power of Nd, Sm, Eu and Gd are reported. The ac electrical conductivity at a few temperature ranges is also given. It is found that it follows the Curie-Weiss law behaviour and this has been attributed to the crystal field effect. The experimental value of Bohr magneton for the magnetic ions has been found to be in good agreement with theory. Thermoelectric power is negative in the measured temperature range suggesting these materials to bep-type semi-conductors and holes as the dominant charge carriers. The results are explained using band theory.     

Luminescence of Ytterbium and Neodymium in Complexes with Bis-Macrocyclic Ligands

We have studied the spectral-luminescent characteristics of ytterbium and neodymium ions in complexes with new polydentate bis-crown-ether and bis-azacyclic ligands both of whose parts are bound by 2,9-substituted 1,10-phenanthroline. The relationship between the intensity, rare-earth ion luminescence lifetime, and the composition of the coordination sphere of the complexes is established. Using the considered compounds as an example, we show the advantage of the joint influence of screening of the central ion from the effect of high-frequency O–H- and C–H vibrations of the solvent molecules and of the photoantenna effect in improvement of the luminescent characteristics of lanthanides.     

89Y NMR Studies of MBE Grown DyFe2/YFe2 Multilayer Films

Hyperfine Interactions - 89Y (spin I=1/2) NMR studies of DyFe2/YFe2 multilayer films at 4.2 K are reported and discussed. Results are presented for a 1000 Å thick film of YFe2, and a 24,000...     

提高能量上转换效率的实验探讨

通过以TeO₂,GeO₂,ZnF₂,SiO₂,PbF₂等为主体的氟氧化物玻璃陶瓷基质材料的研究提出了提高上转换效率的某些条件.选择低声子能量的基质,且基质的M系数接近稀土离子的M系数的氟氧化物基质材料是高效上转材料的基础,选择激发光光子能量与稀土离子、敏化稀土离子能级匹配是高效上转换材料的必要条件.为设计研究稀土掺杂能量上转换材料提供了有理论和应用价值的结果. 关键词： 能量上转换 氟氧化物玻璃陶瓷 稀土掺杂     

稀土固体超强酸SO42-/TiO2/La3+催化合成丁酸异戊酯

丁酸异戊酯是无色至淡黄色透明油状液体,有近似生梨和香蕉香甜气。天然品存在于椰子油、可可豆、苹果、香蕉、葡萄、草莓等中,是我国ＧＢ２７６０－８６规定允许使用的食用香料,主要用以配制香蕉、菠萝、杏、樱桃和杂锦水果等型香精;也可用作提取天然香料的溶剂、乙酸纤维素的溶剂及增塑剂。通常它是在硫酸催化下由丁酸和异戊醉酯化反应而得［１,２］,反应时间长,副反应多,对设备腐蚀严重,废水排放量大,后处理工艺复杂。为此,本实验选用稀土固体超强酸ＳＯ４２－／ＴｉＯ２／Ｌａ３＋作为催化剂进行某些酸与异戊醇的酯化反应。 …     

Evaluating Electron-Transfer Reactivity of Complexes of Actinides in +2 and +3 Oxidation States by using EPR Spectroscopy

The possibility that the relative reactivity of complexes of actinide metals in the +2 and +3 oxidation states could be investigated by examining reactions between An^III and An^II species of Th and U with rare-earth metal reagents that provide EPR confirmation of electron transfer reactivity has been explored. Neither Cp’’₃Th^III nor Cp’’₃U^III will reduce Cp’’₃La^III or Cp’₃Y^III (Cp’=C₅H₄SiMe₃, Cp’’=C₅H₃(SiMe₃)₂). However, both [K(2.2.2-cryptand)][Cp’’₃Th^II] and [K(2.2.2-cryptand)][Cp’’₃U^II] reduce Cp’’₃La^III and Cp’₃Y^III to form [Cp’’₃La^II]¹⁻ and [Cp’₃Y^II]¹⁻, respectively, which were identified by EPR spectroscopy. The reverse reactions also occur which indicates that the reduction potentials are similar. [Cp’’₃La^II]¹⁻ reduces Cp’₃Y^III and the reverse Y^II/La^III combination also occurs. In both cases, the reactions generate EPR spectra indicative of multiple species in the mixtures of La^II and Y^II, which is consistent with ligand exchange and demonstrates that numerous heteroleptic complexes of these Ln^II ions exist.     

环烷酸稀土化合物的摩擦学性能研究

用四球摩擦磨损试验机考察了环烷酸稀土化合物在26#白油中的摩擦学性能，探讨了其同硫系、磷系添加剂的复配作用，并用Auger电子能谱仪和X射线光电子能谱仪研究了钢球磨斑表面边界膜的化学组成和元素分布．结果表明：在边界润滑条件下，环烷酸稀土化合物作为润滑油添加剂具有良好的抗磨性能和承载能力，并具有一定的减摩能力；环烷酸稀土与硫系添加剂复配后极压性能大幅度提高，而与磷系添加剂无协同作用．稀土添加剂在摩擦表面形成富稀土边界膜是该添加剂具有优异摩擦学性能的主要原因．