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).     

溶胶-凝胶法制备Y2Zr2O7∶Tm3+及其发光性能研究

以柠檬酸为络合剂采用溶胶-凝胶法制备了（Y1-xTmx）2Zr2O7（x=0.005,0.01,0.03,0.05）荧光粉.采用X-射线衍射分析仪（XRD）、扫描电子显微镜（SEM）和荧光光谱仪分别检测了Y2Zr2O7∶Tm3+的晶体结构、颗粒形貌以及样品的荧光光谱.XRD图谱表明,所得到的产物Y2Zr2O7∶Tm3+为单一相的萤石结构,而且Tm3+的掺杂并没有改变其晶体结构.荧光光谱的测试表明,在359 nm波长的紫外光激发下,1000℃下烧结的（Y1-xTmx）2Zr2O7（x=0.01）样品的发光性能最好,发射峰对应于Tm3+的1D2→3F4跃迁和1G4→3H6跃迁,并对其发光机理进行了探讨.样品在454 nm处的发光强度随Tm3+离子掺杂浓度的增加先升高后降低,即出现了浓度猝灭的现象,当Tm3+掺杂浓度摩尔百分比为1%时,样品的发光强度达到最大.     

Tm:YAG光纤生长中熔区光谱的研究

本文报道了用激光加热基座法生长Tm：YAG单晶光纤时，光照区在不同加热功率下光谱变化及其响应时间，分析了形成的原因。     

Tm,Ho声光调Q激光系统理论与实验研究

利用激光速率方程理论,对Tm,Ho激光系统计算预测得出最佳耦合输出透过率和调Q激光脉冲宽度.实验采用Tm, Ho:LuLF为增益介质,三向侧面泵浦,环形腔声光调Q.选用透过率20%和30%的输出镜作对比.在透过率20%耦合输出时,得到调Q激光脉冲能量最大为58.0 mJ,对应光光转换效率为1.45%;在透过率30%耦合输出时,得到调Q激光脉冲能量最大为62.9 mJ,对应光光转换效率1.57%,并且获得了最大动静比48.7%.激光脉冲宽度在注入能量3.25 J时为417.2 ns.与理论计算结果较为一致.     

掺Tm3+光纤激光器的进展

总结分析了近期连续波输出、脉冲输出和上转换连续波输出的掺，Tm^3 光纤激光器现状。指出采用Tm^3 分别与Yb^3 、Ho^3 和Al^3 共掺的光纤，可使掺Tm^3 光纤激光器扩展抽运源波长、压缩调Q脉宽和提高斜率效率。     

Frequency up-conversion luminescence properties and mechanism of Tm<Superscript>3+</Superscript>/Er<Superscript>3+</Superscript>/Yb<Superscript>3+</Superscript> co-doped oxyfluorogermanate glasses

Oxyfluoride glasses were developed with composition 60GeO 2 ·10AlF 3 ·25BaF 2 ·(1.95-x)GdF 3 · 3YbF 3 ·0.05TmF 3 ·xErF 3 (x=0.02,0.05,0.08,0.11,0.14,0.17)in mole percent.Intense blue(476 nm),green(524 and 546 nm)and red(658 nm)emissions which identified from the 1G 4 →3H 6 transition of Tm3+and the(2H 11/2 ,4S 3/2 )→4I 15/2 ,4F 9/2 →4I 15/2 transitions of Er3+,respectively,were simultaneously observed under 980 nm excitation at room temperature.The results show that multicolor luminescence including white l...     

Tm3+-doped tellurite glass with Yb3+ energy sensitized for broadband amplifier at 1400-1700 nm bands

A kind of novel experiment was disclosed as it possessed two bands of fluorescence emission at 1.4 and 1.6 μm, which were per-fectly complimentary to the current C band of optic communication. The fluorescence was based on energy transfer and up-conversion proc-esses between Tm3+ and Yb3+ under direct pumping of 975 nm LD. The spectra and lifetimes of Tm3+ fluorescence in the tellurite glass were described. The corresponding fluorescence characteristics and energy migration process were analyzed by the method of lifetime and inten-sity comparison. The mechanism of the up-conversion based IR fluorescence was presented upon analyzing the multi-photon pumping proc-ess. The potential advantages of Tm3+/Yb3+ co-doped tellurite glass as amplifier material were concluded.     

Effect of Tm2O3 on the properties of corundum-mullite composite ceramics for solar heat transmission pipelines

Corundum-mullite composite ceramics appropriate for application in solar heat transmission pipelines were fabricated by the addition of Tm₂O₃ and sintered at atmospheric pressure. The results demonstrated that with the introduction of Tm₂O₃ (1–7 wt.%), the physical and mechanical properties, corrosion resistance, and thermal shock resistance of the composite ceramics were significantly enhanced. The sintered sample AT5 (with 5 wt.% of Tm₂O₃ added) showed the best overall performance at 1550°C. The residual bending strength remained higher than 186 MPa after corrosion with 20 wt.% H₂SO₄ solution and 10 wt.% sodium hydroxide solution. The reaction of Tm₂O₃ with the Al₂O₃–SiO₂ system produced the Tm₂O₃–Al₂O₃–SiO₂ liquid phase. This liquid phase eliminated the pores through viscous flow, resulting in a dense microstructure. Furthermore, more mullite and dithulium disilicate were generated after thermal shock cycles, and their inhibition of crack deflection and extension allowed the composite ceramics to achieve excellent thermal shock resistance (residual bending strength as high as 199 MPa). The prepared corundum-mullite composite ceramics have a good potential for application in solar heat transmission pipelines.     

Water effect on the morphology of EVOH copolymers

The effect of water on the morphology of four ethylene vinyl alcohol copolymers (EVOH) with different ethylene contents was studied by differential scanning calorimetry (DSC). EVOH film samples equilibrated in controlled atmospheres at different relative humidities (RH) and 23°C were analyzed. Under dry conditions, the glass transition temperature (T_g) was unaffected by copolymer ethylene content. As RH increases, T_g decreases. It seems that the presence of water within the polymer matrix results in plasticization of the polymer. T_g varies from around 50°C (dry) to below room temperature. EVOH copolymers are glassy polymers when dry and rubbery polymers at high RHs. Fox and Gordon–Taylor's equations well describe T_g depletion at low water uptake, although severe water gain results in a considerable T_g decrease, which is not predicted by these theories. Melting temperature, T_m, and enthalpy, ΔH_m, were also analyzed. When dry, T_m decreases as ethylene content increases. No significant water effect was found on either T_m or ΔH_m. Hence, crystallinity seems to be unaffected by water presence. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1201–1206, 1999     

Upconversion emission of SrYbF5：Er3＋nanosheets modified by Tm3＋ions

Through a hydrothermal route, the Er3＋and Tm3＋co-doped SrYbF5 nanosheets were synthesized. The resulting samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and luminescence spec-tra. Under the excitation of 980 nm laser irradiation, the upconversion emissions of Tm3＋ions centered at 474 nm （1G4→3H6）, 679 nm （3F2→3H6）, 699 nm （3F3→3H6）, 803 nm （3H4→3H6） and emissions of Er3＋ions centered at 522 nm （2H11/2→4I15/2）, 543 nm （4S3/2→4I15/2）, 654 nm （4F9/2→4I15/2） were observed. The upconversion emissions of Er3＋ions were adjusted by the concentration of Tm3＋ions. The energy transfer mechanisms among Er3＋-Yb3＋-Tm3＋in SrYbF5 nanosheets were discussed.