Study on Effect of Flux on CeMgAl11O19：Tb^3＋ Phosphor

High calcination temperature is an important factor in the preparation process of CeMgAl11O19:Tb^3 . To decrease the temperature, different fluxes (H3BO3, MgF2 and AlF3) were tested in order to compare their influence on the luminescence property and particle size distribution of CeMgAl11O19: Tb^3 . The result shows that when the content of MgF2 is 0.1 mol/mol, the intensity of luminescence can attain a maximum. Furthermore, MgF2 can improve the particle size quality of the phosphor. So MgF2 can take the place of the conventional flux H3BO3 to prepare high quality CeMgAl11O19:Tb^3 phosphor. In addition, the relation between phosphor property and content of AlF3 was also studied. The crystal structure of the phosphor was analyzed by XRD method. The phase composition analysis shows that the reason of decrease of the brightness of CeMgAl11O19:Tb^3 phosphor is the emergence of TbAlO3 and α-Al2O3 during the preparation process.     

Preparation of Y2O3：Eu^3＋ phosphor by molten salt assisted method

A kind of fine and quasi-spherical Y2O3：Eu^3＋ phosphor was prepared by firing a preparative precursor at 1 200 ℃ for 2 h with the molten salts of Na2CO3, S and NaCl. The precursor was obtained by homogeneous precipitation of yttrium and europium with oxalic acid when using EDTA, citric acid or starch as complexant. The structure and morphology of the phosphors were characterized by XRD and SEM, respectively. The influence of complexing environment, firing temperature and molten salts on formation of the phosphor Y2O3：Eu^3＋ was discussed. The result show that the prepared Y2O3：Eu^3＋ phosphor is of quasi-spherical structure with size of 2-3 μm. Its luminescent intensity is 30% higher than that of the same phosphor prepared by the same procedure but without molten salts, and is 5% higher than that of commercial Y2O3：Eu^3＋ red phosphor.     

烟丝组分的吸湿模型研究

为了研究烟丝主要组分的吸湿平衡规律,用GAB模型获得的叶丝、梗丝、膨胀烟丝在25℃环境下,在45%～75%平衡相对湿度范围内的吸湿平衡,得到优异的拟合精度.结果表明,用GAB吸湿模型计算的叶丝、梗丝、膨胀烟丝的单层含水率（干基）分别为6.14%,7.04%,5.92%.以水活度0.65为安全贮存的临界点,对应于吸湿过程,用GAB模型估计25℃时叶丝、梗丝、膨胀烟丝的安全含水率（干基）分别为16.69%,18.30%,15.00%.研究结果为各组分加工过程各阶段的含水率设计提供了参考.     

三相电机断相、过载、相序保护器设计

介绍了三相电机的断相、过载和相序保护电路，并详细阐述了其工作原理。     

UT-2000操作控制系统在镜泊湖地下电站中的应用

介绍了UT-2000操作控制系统的配置、功能、主要技术特点及在镜泊湖地下电站4台机组控制系统中的应用与运行效果。     

Luminescence Properties of Eu~(2 ) and Mn~(2 ) Co-Doped Ca_8Mg(SiO_4)_4Cl_2

The green phosphor for white LED, Ca8Mg(SiO4)4Cl2∶Eu2+, Mn2+, was synthesized by high temperature solid state reaction under reducing atmosphere. During the process of the phosphor prepared, the excess CaCl2 can improve the intensity of emission. The experimental results indicate that there is an effective energy transfer from Eu2+ to Mn2+in Ca8Mg(SiO4)4Cl2 host. This kind of energy transfer may be due to resonance transfer, and this energy transfer is limited.     

Luminescence Properties of Eu^2 ＋ and Mn^2 ＋ Co-Doped CasMg（SiO4）4Cl2

The green phosphor for white LED, Ca8Mg(SiO4)4C12:Eu^2 , Mn^2 , was synthesized by high temperature solid state reaction under reducing atmosphere. During the process of the phosphor prepared, the excess CaC12 can improve the intensity of emission. The experimental results indicate that there is an effective energy transfer from Eu^2 to Mn^2 in Ca8Mg(SiO4)4Cl2 host. This kind of energy transfer may be due to resonance transfer, and this energy transfer is limited     

Co-Precipitation Preparation and Luminescent Behavior of (Y,Gd)BO3∶ Eu Phosphor

(Y,Gd)BO3∶ Eu phosphors were prepared by co-precipitation precursors, and luminescent properties were investigated. The precursors were synthesized by introducing hydroxyl ion to mixed solution of rare earth nitrates and boric acid, either through adding ammonia(precursor 1)or through controlled release of hydroxyl ion of urea(precursor 2). The precursors were fired in air at 1000 ℃ for 2 h. Resulted phosphor synthesized with precursor 1 has non-uniformed particle with mean diameter of about 3 μm, while that with precursor 2 exhibits uniformed near spherical-like morphology with mean diameter of about 300 nm. Phosphors with the two methods exhibit same crystal structure as that of commercial one. Emission spectra of the samples indicate that the sample prepared with precursor 2 shows relative higher intensity(exited by 172 nm VUV)than that prepared with the other precursor.     

Study on purification and application of novel precipitant for ceria-based polishing powder

Novel precipitant prepared through carbonation with MgCl2 wastewater generated from rare earth extraction separation process and low-price dolomite as raw materials was studied in this paper. The purification methods of novel precipitant by adding appropriate oxidizing agent were studied. It was found that optimal purification result could be achieved with sodium hypochlorite as iron removal reagent and the iron removal rate could reach up to 90% when the adding amount was 0.1 vol.%. During the preparation, the particle size and distribution of ceria-based polishing powder were affected obviously by the parameters such as concentration, reaction temperature and feeding rate. The results showed that ceria-based polishing powder with D50 =2.5-3.5 μm and the particle size distribution of 0.65-0.75 μm could be prepared when the concentration of CeCl3 was 0.6 mol/L, the reaction temperature was maintained at 50 °C and the feeding speed was controlled at 25 ml/min. Compared with commercial powder, the self-made polishing powder had roughly the same cutting amount, but the surface finish of polished glass was better than that of commercial polishing powder.