高纯氧化铥的分离制备研究

用ＣＬ－Ｐ５０７－ＨＣｌ体系柱色层法分离原料氧化铥中铒、镱等稀土和非稀土杂质。讨论了树脂粒度、温度、淋洗剂浓度１负载量、进样比等条件对铥、镱 分离的影响,观没蛭铥、镱之间存在萃取抑制现象。选择合适分离条件以９９．９％氧化铥 为原料制备出９９．９９５％的高纯氧化铥产品,其主要稀土杂质铒,镱 均小于５μｇ／ｇ,非稀土杂质铁小于２μｇ／ｇ,钙小于５μｇ／ｇ。     

Sol–gel deposition of multiply doped thermographic phosphor coatings Al2O3:(Cr,M) (M = Dy,Tm) for wide range surface temperature measurement application

A promising method of measuring surface temperatures in harsh environments is the use of thermographic phosphor coatings. There, the surface temperature is evaluated from the phosphorescence decay lifetime following a pulsed laser or flash lamp light excitation. Depending on the used dopant, single doped M³⁺:α-Al₂O₃ (M = Cr, Dy, Tm) emit at 694 nm (Cr³⁺), 488 nm (Dy³⁺), 584 nm (Dy³⁺), and 459 nm (Tm³⁺), respectively. However, the accessible temperature range with a single dopant is limited: for the Cr³⁺-transition from 293 K up to 900 K, and for the Dy³⁺ and Tm³⁺-transitions both from 1073 K up to 1473 K. In the present study a new approach is followed to extend these limitations by co-doping two dopants using the sol–gel method and dip coating of α-Al₂O₃ thin films. For that application (Dy³⁺ + Cr³⁺) co-doped thin α-Al₂O₃ films and (Tm³⁺ + Cr³⁺) co-doped α-Al₂O₃ films with thicknesses of 4–6 μm were prepared, and the temperature-dependent luminescence properties (emission spectra and lifetimes) were analysed after pulsed laser excitation in the UV (355 nm). The phosphorescence lifetime as a function of temperature were measured between 293 K and 1473 K. A considerably extended range for surface temperature evaluation was established following this new approach by combining different dopants on the molecular level.     

Novel Tm-doped fluorotellurite glasses with enhanced quantum efficiency

In this paper, new highly Tm³⁺-doped tellurite glasses with host composition 75TeO₂-xZnF₂-yGeO₂-12PbO-3Nb₂O₅ [x(5-15), y(0-5) mol%] are presented and compared to the Tm-doped tellurite glasses based on the traditional host composition: 75TeO₂-20ZnO-5Na₂O mol%. Enhanced quantum efficiency from ³F₄ level was observed for the proposed glasses and thermal stability and viscosity values make them suitable for optical fiber drawing. Besides the host composition, substantial influence of Tm³⁺ concentration on luminescence and lifetime of excited ³F₄ and ³H₄ states were discussed.     

Electrochemistry of thulium on inert electrodes and electrochemical formation of a Tm–Al alloy from molten chlorides

The electrochemical behaviour of TmCl₃ solutions was studied in the eutectic LiCl–KCl in the temperature range 673–823 K using inert and reactive electrodes, i.e. W and Al, respectively.On an inert electrode, Tm(III) ions are reduced to metallic thulium through two consecutive steps:

Tm(III) + 1e ↔ Tm(II) and Tm(II) + 2e ↔ Tm(0)

The electroreduction of Tm(III) to Tm(II) was found to be quasi-reversible. The intrinsic rate constant of charge transfer, k⁰, as well as of the charge transfer coefficient, α, have been calculated by simulation of the cyclic voltammograms and logarithmic analysis of the convoluted curves. Electrocrystallization of thulium plays an important role in the electrodeposition process, being the nucleation mode affected by temperature.The diffusion coefficients of Tm(III) and Tm(II) ions have been found to be equal. The validity of the Arrhenius law was verified by plotting the variation of the logarithm of the diffusion coefficients vs. 1/T.The electrode reactions of Tm(III) solutions at an Al electrode were also investigated. The results showed that for the extraction of thulium from molten chlorides, the use of a reactive electrode made of aluminium leading to Al–Tm alloys seems to be a pertinent route.Potentiometric titrations of Tm(III) solutions with oxide donors, using a ytria stabilized zirconia electrode “YSZE” as a pO²⁻ indicator electrode, have shown the formation of thulium oxychloride and thulium oxide and their corresponding solubility products have been determined at 723 K (pk_s(TmOCl) = 8.0 ± 0.3 pk_s(Tm₂O₃) = 18.8 ± 0.7).     

Microstructure and morphology of Mo-based Tm2O3 composites synthesized by ball milling and sintering

Mo-based Tm₂O₃ composites used as neutron absorbers were synthesized by ball milling, cold isostatic pressing and sintering. The size of Mo grain was decreased rapidly in the initial stage and then kept a constant in the later stage. After ball milling for 96 h, the size of Mo grain was up to approximately 8 nm. Ball milling induced Tm₂O₃ to be first fined, nano-crystallized, then transformed to amorphization, and finally dissolved into Mo crystal. The supersaturated nanocrystalline solid solution of Mo (Tm, O) was formed after 96 h of ball milling. Sintering caused Tm and O atoms precipitated from Mo crystal and then formed Tm₂O₃ precipitates that uniformly distributed in the Mo matrix. After sintered for 12–24 h at 1400–1600 °C, only diffraction peaks of Tm₂O₃ and Mo could be observed in the XRD spectrums, which indicated that there was not a chemical reaction between Tm₂O₃ and Mo. The microhardness of sintered bulks increased with increasing ball-milling time, sintering temperature and time, and the chemical content of Tm₂O₃ in the powder mixtures. The evolutionary mechanism of the microstructural characteristics during ball milling and subsequent sintering was discussed.     

Crystallographic data of the ternary compounds RRhGe (R=Gd-Tm) of the TiNiSi-type structure

Investigations made by powder X-ray diffraction on the new ternary TmRhGe compound and already known RRhGe compounds (R=Gd-Er) are reported. They crystallize in the well-known orthorombic TiNiSi-type structure (space group Pnma).     

Anneal temperature dependent Er/Tm energy transfer and luminescence from Er and Tm co-doped silicon-rich silicon oxide

The effect of the anneal temperature on the Er³⁺/Tm³⁺ energy transfer and subsequent Er³⁺/Tm³⁺ luminescence from Er/Tm co-doped, silicon-rich silicon oxide films are investigated. The anneal procedure necessary for optimum photoluminescence (PL) from the co-doped film is substantially different from that for only Er- or Tm-doped films. Analysis and modeling of PL intensity and time-resolved PL indicate that this higher optimum anneal temperature is due to the anneal temperature dependent Er-Tm interactions. In addition, the optimization of combined ultrabroad Er/Tm luminescence was discussed controlling Er-Tm interactions which is tailored by the change of Er/Tm doping ratio and anneal temperature.     

Ball-milling properties and sintering behavior of Fe-Tm2O3 mixture powders

Aimed at the existing problems of current neutron absorbers that were used in control rods to safely operate a nuclear reactor, new type of Fe-based Tm₂O₃ composites and Fe-based TmFeO₃ composites, which were synthesized from the Fe-25.68 wt.%Tm₂O₃ mixture powders by ball milling, cold isostatic pressing and sintering, were designed as next generation neutron absorbers in the present work. During ball milling, Tm₂O₃ was fined, nano-crystallized, amorphized and then dissolved into Fe crystal lattice to form Fe (Tm, O) nanocrystalline solid solution. The effect of sintering temperature and oxygen content at sintering environment on the phases of the sintered bulks were researched, and the corresponding mechanism was discussed. Nanoscale TmFeO₃ and Tm₂O₃ particles were distributed in the sintered bulk matrix. The microhardness, compression strength, and the coefficients of thermal expansion of the bulks sintered at different conditions were measured and discussed. The coefficient of linear expansion and compressive strength increased with increasing ball-milling time. The microhardness increased with increasing sintering temperature when the temperature was lower than 1200 °C. Meanwhile, the microhardness and compressive strength of Fe-based Tm₂O₃ composites were larger than that of Fe-based TmFeO₃ composites, opposite for the coefficients of thermal expansion.     

Eyesafe high peak power pulsed fiber lasers limited by fiber nonlinearity

We present design and performances of several eye-safe high peak power fiber lasers operating either around 1550 nm or 2000 nm. They share the limitations by nonlinear effects either Stimulated Brillouin Scattering for single frequency lasers or Kerr related effects for short pulse amplifiers. Performances above 1 kW peak power for single frequency lasers and 26 nJ for short pulse fiber lasers are reported. The influence of the saturation power of the fibers on the non-linearity is discussed and applied to a comparison between Erbium and Ytterbium co-doped fibers and Thulium doped fibers. The Brillouin gain properties in these fibers are also compared.     

Wavelength-tunable thulium-doped single mode fiber laser based on the digitally programmable micro-mirror array

We propose a wavelength-tunable thulium-doped single mode fiber laser with a digitally controlled micro-mirror array device. The fast and flexible lasing wavelength switching property was achieved by the pixelated spatial modulation of the micro-mirror array. The proposed laser provides a maximum output power of 160 mW with 24% slope efficiency and a narrow output linewidth of less than 0.03 nm. The operating wavelength is continuously tunable from 1863 nm to 1937 nm with a wavelength selectivity accuracy of less than 0.4 nm and a fast switching time of ∼75 μs.