Optical and Scintillation Properties of Ce3+‐Doped LuAG and YAG Transparent Ceramics: A Comparative Study

Cerium‐doped lutetium aluminum garnet (LuAG:Ce) and yttrium aluminum garnet (YAG:Ce) transparent ceramics of same dimension were fabricated and their optical and scintillation properties were studied. LuAG:Ce transparent ceramic showed higher light yield under UV and X‐ray excitation with respect to YAG:Ce transparent ceramic. YAG:Ce transparent ceramic showed higher light yield under gamma excitation and better energy resolution, which could be due to the considerable amount of slower emission (38.5%) in LuAG:Ce as well as lower optical transparency with respect to YAG:Ce ceramic.     

Polycrystalline Ho: LuAG laser ceramics: Fabrication,microstructure, and optical characterization

Ho:Lu₃Al₅O₁₂(LuAG) transparent ceramics are potential 2 μm eye‐safe laser materials. Polycrystalline 0.8 at.% Ho:LuAG ceramics with high optical quality were successfully fabricated by solid‐state reactive sintering of high‐purity oxide powders. The microstructure, the optical transmission, the spectrum characteristic, and the laser performance were investigated in this paper. The average grain size of Ho:LuAG ceramics vacuum sintered at 1830°C for 30 hour is about 14 μm. The in‐line transmittance of the sample is measured to be 81.7% and 82.0% at 1000 and 2250 nm, respectively. The absorption and the emission cross sections are calculated to be 0.88 × 10^?20 cm² at 1906 nm and 1.26 × 10^?20 cm² at 2094 nm. Using a thulium‐doped yttrium‐lithium‐fluoride (Tm:YLF) laser with the central wavelength of 1907.5 nm as the pump source, 2.67 W continuous wave (CW) laser operation at 2100.74 nm was obtained with a slope efficiency of 26.5%. The beam quality factor M² was calculated to be 1.1, which indicated nearly diffraction‐limited beam propagation and the laser was the fundamental TEM₀₀ Gaussian mode.     

Submicron-grained Yb:Lu2O3 transparent ceramics with lasing quality

We report on our recent progress of fabricating Yb³⁺-doped Lu₂O₃ transparent ceramics for 1 μm solid-state laser application. Well-dispersed 3.3 at.% Yb:Lu₂O₃ nanopowders were synthesized using a co-precipitation method. Without using any sintering aids, the Yb:Lu₂O₃ nanopowders could be densified by vacuum sintering at 1500°C/10 hours followed by HIPing at 1480°C/4 hours. Such obtained Yb:Lu₂O₃ ceramics had not only dense microstructure and submicron grain size of about 0.6 μm, but also in-line transmission of 80.0% at 600 nm. Preliminary continuous wave (CW) laser experiments with an uncoated Yb:Lu₂O₃ ceramic slab have demonstrated highly efficient CW laser oscillation at 1079.8 nm.     

Photoluminescent and scintillant properties of highly transparent [(Y1-xGdx)0.99Dy0.01]2O3 (x = 0 and 0.4) ceramics

High-optical-quality ternary [(Y_1-xGd_x)_0.99Dy_0.01]₂O₃ (x = 0 and 0.4) ceramics were successfully fabricated by vacuum sintering with in-line transmittances of 71.4%-75.1% at 574 nm, the wavelength of Dy³⁺ emission (the ⁴F_9/2 → ⁶H_13/2 transition). Substitution of Gd³⁺ for Y³⁺ significantly affected the photoluminescent and scintillant properties of the ceramics. Gd³⁺ addition effectively increased lattice parameters and theoretical densities of the ceramic samples; this contributed to enhanced X-ray absorption coefficients. Both [(Y_1-xGd_x)_0.99Dy_0.01]₂O₃ (x = 0 and 0.4) ceramics displayed typical Dy³⁺ emissions from ⁴F_9/2 → ⁶H_J (J = 15/2, 13/2, 11/2) transitions under UV and X-ray irradiations. By incorporating Gd³⁺ into the lattice, a stronger excitation peak of Gd³⁺ due to internal f-f transitions relative to Dy³⁺ was observed at 276 nm; subsequent ceramics obtained a sharper PL intensity and a warmer hue via effective energy transfer from Gd³⁺ to Dy³⁺. Using a Gd³⁺ dopant generally reduces the total photoluminescence/photoluminescence excitation intensities and light output; it also delays the lifetime and afterglow of the transparent ceramics.     

不饱和聚酯漆防沉体系的探讨

与滑石粉比较,透明粉在不饱和聚酯漆施工兑稀后更易沉降,通过一系列较为系统的实验,对影响不饱和聚酯漆沉降的主要因素进行探讨,提出了解决涂料兑稀后沉降的方法。     

可逆热透明成像材料记录层的制备及形态与性能的研究

以纤维素为基体树脂,硬脂酸、聚乙二醇硬脂酸酯等为添加物,制备了1种可逆热透明成像材料的热敏记录层。利用差示扫描量热仪、偏光显微镜等研究了记录层材料热变化中的形态与性能。研究表明,该记录层具有良好的热光性质,硬脂酸和聚乙二醇硬脂酸酯的协同作用使得记录层的光学和热学性质有了进一步的提高。     

BSTS透明微晶玻璃及其三阶非线性光学性能

以SrO-BaO-TiO2-SiO2(简称BSTS)为基础玻璃系统,通过热处理工艺研究,制备出了以极性晶体Ba2-xSrXTiSiO8为主晶相的透明微晶玻璃,利用光学克尔系统测定了微晶玻璃的三阶非线性光学系数,实验表明,微晶玻璃的三阶非线性效应源于电子响应,基本没有振动转动等其它弛豫过程.     

Nd:YAG透明陶瓷制备技术的研究进展

掺钕钇铝石榴石(Nd：YAG)透明陶瓷是新一代固体激光材料。同Nd：YAG单晶和钕玻璃相比，Nd：YAG透明陶瓷及其制备技术具有许多优点，例如可获得掺杂浓度更高、尺寸更大的材料，可实现多层、多功能陶瓷复合结构，同时成本较单晶生长低，可实现大规模生产等，因而受到广泛重视。文中对近年来Nd：YAG透明陶瓷激光材料的研究进展、制备技术及其激光器的发展进行了综合评述，并展望了其应用前景。     

透明砂土休止角和起动流速基本特性试验研究

人工合成透明土材料结合粒子图像处理技术在模型试验中已得到广泛应用,但使用该技术研究桩基冲刷问题还需对其开展更多特性研究.基于熔融石英砂与正十二烷和15#白油混合液制备成透明砂土,通过室内试验研究透明砂土的基本物理特性、休止角和起动流速.结果 表明:透明砂土的透明度除1～2 mm粒径组显著较差外,其余相差不大;各粒径组透...     

Er3+,Er3+-Yb3+和Er3+-Na+掺杂CaF2透明陶瓷的光学性能

以Ca(NO3)2、Er(NO3)3、Yb(NO3)3、KF和NaF为原料,采用热压烧结方法制备出Er3+,Er3+-Yb3+和Er3+-Na+掺杂CaF2透明陶瓷。测试了样品室温吸收光谱和发射光谱。利用Judd-Ofelt理论分析了样品的光学性能,并对吸收光谱进行计算拟合,得到光谱参数?t (t=2,4,6),根据光谱参数?t计算出Er3+某些能级的的跃迁几率、荧光分支比、辐射寿命和品质因子,讨论并比较了Er3+-Yb3+和Er3+-Na+共掺对CaF2透明陶瓷光学性能的影响。结果表明：掺杂Yb3+和Na+改变了Er3+光谱参数;Er3+-Yb3+共掺有利于提高样品的荧光强度;Er3+-Na+共掺有利于提高荧光寿命。