移动区熔法生长全无机钙钛矿型CsPbBr3晶体及其性能研究

利用自制移动区熔炉生长了CsPbBr₃晶体, 事先采用相同工艺合成了高纯多晶原料以去除杂质和水分。通过工艺优化获得了大尺寸CsPbBr₃晶体, 达到ϕ25 mm× 60 mm。该晶体呈橘红色, 在600~2000 nm波长范围内具有透过率达78.6%的优异透光性能。热分析表明, 所得CsPbBr₃晶体在88.1℃和131.25℃时存在正交-四方和四方-立方相变。计算得到CsPbBr₃晶体的带宽E_g= 2.25 eV。上述结果表明移动区熔法是一种具有应用潜力的制备高质量大尺寸CsPbBr₃晶体的生长方法。     

Spectral properties and energy transfer in Er3+/Yb3+ co-doped LiYF4 crystal

Laser crystals of LiYF4 (LYF) singly doped with Er3+ in 2.0% and co-doped with Er3+/Yb3+ in about 2.0%/1.0% molar fraction in the raw composition are grown by a vertical Bridgman method. X-ray diffraction (XRD), absorption spectra, fluorescence spectra and decay curves are measured to investigate the structural and luminescent properties of the crystals. Compared with the Er3+ singly doped sample, obviously enhanced emission at 1.5 μm wavelength and green and red up-conversion emissions from Er3+/Yb3+ co-doped crystal are observed under the excitation of 980 nm laser diode. Meanwhile, the emission at 2.7 μm wavelength from Er3+ singly doped crystal is reduced. The fluorescence decay time ranging from 18.60 ms for Er3+ singly doped crystal to 23.01 ms for Er3+/Yb3+ co-doped crystal depends on the ionic concentration. The luminescent mechanisms for the Er3+/Yb3+ co-doped crystals are analyzed, and the possible energy transfer processes from Yb3+ to Er3+ are proposed.     

Enhanced emission of 2.9 μm from Ho3+/Pr3+ co-doped LiYF4 crystal excited by 640 nm

The use of Pr3+co-doping for great enhancement of mid-infrared(mid-IR) emissions at 2.9 μm and 2.4 μm is investigated in the Ho3+/Pr3+co-doped LiYF4 crystals.With the introduction of Pr3+ions,the fluorescence lifetime of Ho3+:5I7 level is 2.15 ms for Ho3+/Pr3+co-doped crystal,and the lifetime for Ho3+singly doped crystal is 17.70 ms,while the lifetime of Ho3+:5I6 level decreases slightly from 2.11 ms for Ho3+:LiYF4 to 1.83 ms for Ho3+/Pr3+:LiYF4.It is also demonstrated that the introduction of Pr3+greatly increases the mid-infrared emission of Ho3+:5I6 →5I7 which depopulates the Ho3+:5I7 level,while it has little influence on the Ho3+:5I6 level,which is beneficial for greater population inversion and laser operation.The analysis on the decay curves of the 2.0 μm emissions in the framework of the Inokuti-Hirayama model indicates that the energy transfer from Ho3+to Pr3+is mainly from electric dipole-dipole interaction.The calculated efficiency of energy transfer from Ho3+:5I7 to Pr3+:3F2 level is 87.53% for Ho3+/Pr3+(1.02%/0.22%) co-doped sample.Our results suggest that the Ho3+/Pr3+co-doped LiYF4 single crystals may have potential applications in mid-IR lasers.     

LiYF4:Tm3＋单晶的生长及其光学性能研究

采用坩埚下降法,制备了尺寸为Φ10mm×110mm的高质量Tm³⁺掺杂LiYF₄(YLF :Tm3＋)单晶体。测试了样品的电感耦合等离子(ICP)、X光衍射(XRD)吸收光谱 以及790nm LD激发 下的荧光光谱。应用Judd-Ofelt理论计算了Tm³⁺在YLF∶Tm3＋单晶 材料中的唯象强度参数Ω_t、能级跃迁振子强度Pexp、 自发辐射跃迁几率A、荧光分支比β和辐射寿命τrad 等光谱参数,同时计算了1800nm波段的吸收截 面和受激发射截面分别 为σabs=0.52×10－20 cm²和σem=0.67×10 －20 cm²。在荧光光谱中观察到1470nm与1 800nm的荧光发射,它们分别对应于Tm³⁺的³H₄→³F ₄与³F₄→³H₆的能级跃迁。测定了1800nm波段的荧光寿命 ,并计算得到³F₄→³H₆跃迁的量子效率为79.22%。     

CB—6／CB—7重整催化剂的水氯平衡控制

水氯平衡的良好控制将使催化剂的活性、稳定性和选择性得到最佳发挥，也是提高重整转化率的关键所在。但水氯平衡是个动态平衡，水氯平衡失调在实际生产中是经常遇上的问题，为进一步加强CB－6／CB－7重整催化剂的水氯平衡的控制，通过对目前水氯平衡操作和控制方法的分析和探讨，找出在水氯平衡控制中分析检测系统的不完善、计算方法的不精确、注水、注氯设备运行工况不佳等存在的不足之处，并提出相应的优化措施。     

滤碱机转鼓的改造

通过对滤碱机的转鼓筋板处的改造,解决了滤布、铁丝破碎严重的问题;并且提高了重碱烧成率,节约蒸汽和水。     

面向大空间烟气余热的管式温差发电装置研究

电厂等工业领域存在大量高温烟气，温度为100～150℃,有大量余热可回收利用。温差发电技术在中低温余热能量回收中有重要应用，但现有的温差发电装置通常将烟气引入装置内部进行换热发电，难以满足电厂等大空间烟气余热场景的工程应用需求。对此，设计研制了一款使用方式类似于低压省煤器，可放置于烟气内部的管式温差发电装置。搭建了大型烟道试验平台，研究烟气温度、烟气流速、冷却水流速对管式温差发电装置发电性能的影响规律。当进口烟气温度为150℃,烟气流速为1.8 m/s,冷却水温度为20℃,冷却水流速为1.15 m/s时，获得37.35 W的输出功率，并且转换效率达到1.95%。这一研究为温差发电装置的设计提供了新思路，对推动温差发电技术走向工程应用具有重要意义。