Study on preparation and luminescent properties of Eu3+-doped LaAlO3 and GdAlO3

Eu³⁺-doped trigonal LaAlO₃ and orthorhombic GdAlO₃ phosphors have been successfully synthesized by sol–gel method. The crystallization processes of the phosphors have been characterized by X-ray diffraction (XRD) and thermogravimetry-differential scanning calorimetry (TG-DSC). The optical properties of these phosphors were investigated using the photoluminescence (PL) and photoluminescence excitation (PLE) spectra. The influences of the different structures and bonding of the hosts on the luminescence performance of Eu³⁺ ion-doped LaAlO₃ and GdAlO₃ were investigated in detail based on chemical bond theory. Under appropriate UV-radiation, the reddish orange light emitted from GdAlO₃:Eu³⁺ was brighter than that from LaAlO₃:Eu³⁺. Such a brightly luminescent phosphor could be considered as an ideal optical material for the development of new optical display systems.     

Effects of Zr/Ce molar ratio and water content on thermal stability and structure of ZrO2–CeO2 mixed oxides prepared via sol–gel process

ZrO₂–CeO₂ mixed oxides were synthesized via sol–gel process. Thermal stability, structure and morphology of samples were investigated by powder X-ray diffraction, FT-Raman spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. In this approach, the solvent composition and Zr/Ce molar ratio have great influences on the structure and morphology of final products. With decreasing water content in the mixed solvent, specific surface area of powders increased and the single tetragonal phase was obtained. Only when the volume ratio of water and ethanol and the Zr/Ce molar ratio were 1:1, tetragonal t″-Zr_0.5Ce_0.5O₂ could be stabilized in powders at temperature as high as 1000 °C. Meanwhile, tetragonal (t′) and (t″) phases coexisted in Zr_0.5Ce_0.5O₂ solid solution without peak splitting after calcination at 1100 °C, further transforming into cubic and tetragonal (t′) phases at 1200 °C. The effective activation energy for Zr_0.5Ce_0.5O₂ nanocrystallite growth during annealing is about 5.24 ± 0.15 kJ/mol.     

Tuning of crystal phase and luminescence properties of Gd2(MoO4)3:Dy3+ phosphors

The orthorhombic and monoclinic Gd₂(MoO₄)₃:Dy³⁺ were successfully synthesized by a hydrothermal process with a subsequent annealing treatment at 800 °C for 4 h. The crystal phase of Gd₂(MoO₄)₃:Dy³⁺ was controlled as a function of the pH value of the solution. The crystallization and microstructures of the samples were characterized by Powder X-ray diffraction (XRD) and scanning electron micrograph (SEM). Furthermore, the optical properties were investigated by the diffuse reflection, excitation and emission spectra. The mechanisms of different crystal phases affected on the luminescence properties of Gd₂(MoO₄)₃:Dy³⁺ were discussed. The electric dipole–dipole interaction between Dy³⁺ ions was identified as the main mechanism for the concentration quenching of the two structures. Finally, the chromatic natures of all the samples were analyzed in detail. The results indicate that the orthorhombic phosphor Gd_1.84(MoO₄)₃:Dy_0.16³⁺ can be considered as a suitable candidate for white light emitting diodes (W-LEDs).     

Gd3-xCuxAl2系合金磁热效应的研究

采用真空高频磁悬浮炉制备出一系列Gd3-xCuAl2(x=0,0.1,0.2,0.3)合金.通过Cu对Gd的部分替代,研究了Cu元素微量替代对Gd3Al2合金磁热效应的影响.结果表明,Gd3-xCuxAl2系合金的结构同样为Zr3Al2型;在1.5T磁场下,随着Cu含量的增加,Gd3-xCuxAl2系合金的最大绝热温变下降,居里温度提高.说明Cu对Gd的部分替代改变了Gd3Al2合金磁热效应.     

整合机载CASI和SASI高光谱数据的北方森林树种填图研究

将机载CASI和SASI高光谱数据整合,既可以获取可见光-近红外-短波红外区间连续的窄波段地物光谱,又能得到很高的空间分辨率,为高覆盖度的森林树种识别又增加了一种新方法。但是由于两种传感器的光谱响应不同,接收到的辐射值差异较大,如何将两种数据有效整合目前仍是一个难题。CASI和SASI覆盖谱段不同,受大气影响程度也不同,根据植被反射和吸收光谱特性,首先用基于统计模型的经验线性法和基于辐射传输的MODTRAN模型分别对CASI和SASI大气校正,复原地物光谱真实的反射率。然后去除反射率光谱包络线,用Savitzky\|Golay滤波函数对归一化后的光谱曲线进行平滑,以去除噪声及异常点,实现CASI和SASI数据（CASI+SASI）的整合。与实测光谱曲线对比发现,整合后的CASI+SASI光谱曲线与实测光谱曲线匹配度较高,并且比单一传感器的光谱信息更丰富,有利于不同树种的区分识别。最后应用光谱微分及曲线匹配技术,选取SVM分类器实现了研究区的树种填图,总体精度达到86.21%,Kappa系数为0.8297,该方法有效可行,为后续的相关研究提供了参考。     

释水引起的含水层系统沉降试验研究

针对含水层释水引起地面沉降问题,研制了地面沉降试验装置,进行了释水条件下含水层系统沉降试验及禁采或回灌水条件下回弹试验,并分析了各分层沉降对水位变化的响应特征.结果表明,砂层、粘性土层的沉降与水位的变化具有较好的对应关系,粘性土层沉降明显滞后于承压水位的变化,砂层具有较好的弹性,粘性土层塑性变形明显.     

Optimal integration strategies for a syngas fuelled SOFC and gas turbine hybrid

This article aims to develop a thermodynamic modelling and optimization framework for a thorough understanding of the optimal integration of fuel cell, gas turbine and other components in an ambient pressure SOFC-GT hybrid power plant. This method is based on the coupling of a syngas-fed SOFC model and an associated irreversible GT model, with an optimization algorithm developed using MATLAB to efficiently explore the range of possible operating conditions. Energy and entropy balance analysis has been carried out for the entire system to observe the irreversibility distribution within the plant and the contribution of different components. Based on the methodology developed, a comprehensive parametric analysis has been performed to explore the optimum system behavior, and predict the sensitivity of system performance to the variations in major design and operating parameters. The current density, operating temperature, fuel utilization and temperature gradient of the fuel cell, as well as the isentropic efficiencies and temperature ratio of the gas turbine cycle, together with three parameters related to the heat transfer between subsystems are all set to be controllable variables. Other factors affecting the hybrid efficiency have been further simulated and analysed. The model developed is able to predict the performance characteristics of a wide range of hybrid systems potentially sizing from 2000 to 2500 W m⁻² with efficiencies varying between 50% and 60%. The analysis enables us to identify the system design tradeoffs, and therefore to determine better integration strategies for advanced SOFC-GT systems.     

青海青龙沟金矿床地质特征及流体包裹体研究

青龙沟金矿床地质特征研究表明,矿化发生在NW向断裂组及NS向次背斜中,矿石类型为变砂岩、硅化白云石大理岩、蚀变闪长玢岩及绢云千枚岩型,围岩蚀变硅化分2期,表现出该金矿床多期次成矿的过程。流体包裹体研究表明,M2矿体硅化大理岩石英中发育气液二相包裹体,成矿流体属H2O-NaCl体系类型。成矿流体具有低盐度(2.73%~7.99%NaCl)、低密度(0.86~0.95 g/cm3)的特征,成矿温度为123.6~204.5℃,成矿压力为8.99~18.53 MPa,形成深度为0.9~1.91 km,显示出该矿床浅成环境成矿作用下一类成矿流体的性质。     

黑龙江东宁金厂金矿区多元信息量统计成矿预测

金厂金矿床为近年来在黑龙江东宁地区发现的一特大型浅成高硫化型岩浆热液金矿床,其形成与燕山晚期花岗斑岩类等岩浆侵入活动有关。在矿床地质研究基础上,采用多元信息量统计预测方法,在金厂矿区开展了成矿预测研究,圈定了4个进一步找矿工作靶区,为该区进一步找矿勘查工作指明了方向。