等离子体平板显示（PDP）用荧光粉的合成及其光谱性质

等离子体平板显示（PDP）是目前高清晰度、大屏幕平板显示中的佼佼者，使挂壁彩电成为现实，但其关键部分之一-PDP荧光粉的发展却存在着相当滞后的问题，因此急需开发出性能更好的PDP荧光粉或对现有荧光粉的性能进行改善。改善PDP荧光粉性能的重要手段之一是选择合适的合成路径，因此本文探索了软化学合成方法-水热法在合成 PDP荧光粉合成中的应用，同时也采用高温固相法、共沉淀法对PDP荧光粉进行了合成，通过对比分析探索合成方法对PDP荧光粉光谱性质的影响。分别采用水热法、高温固相法、共沉淀法对掺杂稀土发光离子的稀土正硼酸盐（Y，Gd）BO_3、正磷酸盐（La，Gd）PO4、矾酸盐（Y，Gd）VO4、矾磷酸盐Y（P，V）O_4和硼硅酸盐LoBSIOS进行了合成，并用XRD、IR、SEM、XPS、TG-DTA等手段对其结构进行了表征，对上述PDP荧光粉的真空紫外（VUV）光谱、紫外可见光谱及发射光谱性质进行了研究，得到了一些新的、有意义的结果。（1）首次采用水热法以稀土氧化物、氢氧化物或硝酸盐与硼酸为原料合成了（Y,Gd）BO_3：RE~(3+)（RE＝Eu，Th）系列荧光粉，并对其VUV光谱特性进行了研究。sEM分析发现水热法以氢氧化物、硝酸盐合成的荧光粉粒度在100-200nm之间。XPS揭示不同基质中带结构具有一定的差异。光谱分析发现（Y,Gd）BO_3：RE~(3+)的VUV光谱中110-175nm范围内存在着基质硼酸根（B3场）的吸收带，该吸收带随基质中G矛"浓度的增大而增强并发生了红移，认为红移是由于基质中B-O反键轨道能量的变化引起的。对能量传递过程进行分析认为G矛十起到能量传递中间体的作用，使基质对激活剂的敏化效率随G矛十浓度的增大而提高。（Y,Gd）BO3:RE3＋中基质敏化效率的提高也可能是由于基质敏化带的红移使Gd3十或RE3＋更容易从基质中获得能量。我们认为作为PDP荧光粉Eu3＋或Th3＋在GdB03基质中的发光性能更好。对水热合成的（Y,Gd）BO3：Eu~(3+)荧光粉进行热处理发现，荧光粉的亮度随热处理温度的提高而明显增强，说明一定温度下热处理有利于提高荧光粉的发光性能，这可能是由于热处理后荧光粉的结晶度提高，内部缺陷减少。比较水热法、高温固相法和共沉淀法对荧光粉性质的影响时发现三种方法制备的荧光粉光谱特性基本一致，但高温固相法和共沉淀法制备的荧光粉粒度较大，形貌不规则。（2）采用水热法制备了不同G矛十浓度的PDP荧光粉（L a，Gd）Po4：RE3＋（RE＝Eu，Tb），发现以稀土硝酸盐溶液和伽玩）2HPO4为原料，在pH值为5·240oC下反应3天可以合成出结晶度较高的纯相。从SEM照片中观察到水热法制备的荧光粉为晶化很好的棒状晶体。对水热法制备的LaP04：Eu3+和GdPO4：Eu3+进行热处理后发现热处理后晶体的尺寸变小，但形貌没有发生明显的变化，发光性能效果稍有提高。首次对共沉淀法合成的不同Gd3＋浓度的（La，Gd）PO4：KE3＋（RE=Eu，Tb）荧光粉的VUV光谱进行了分析，并研究了Gd3＋在能量传递过程中的作用，发现随基质中Gd3十浓度的增大，基质对发光离子的敏化效率提高，认为Gd3＋起着能量传递中间体的作用。同时观察到（La，Gd）PO4：Eu3+中电荷迁移带随着Gd3＋浓度的增大而发生红移，这也可能会导致基质对Eu3+敏化效率的提高。首次利于xPs分析了LaPO4和GdP04的价带结构，发现LaP04的价带由O2的2P能级构成，而GdPo4的价带则是由O2-的2p能级和Gd3＋的4f能级共同构成，这种价带结构的差异可能对（La，Gd）PO4：RE3＋在VUV区的吸收产生影响。（3）首次对水热法合成的（Y,Gd）VO4：Eu3+的VUV光谱进行了研究，观察到120-170nm范围内存在着vO43一离子团的弱吸收带，200nm处存在着来自2P（O）→4f（Y）或5d（均跃迁的激发带，20onm以后的激发宽带是由Eu3＋的电荷迁移带与VO43-的吸收带重叠而成的。对不同Gd3＋浓度的（Y，Gd）VO4：E矿"的vLJ'v光谱进行研究发现，在一定G矛＋浓度范围内Gd3＋的加入使基质vo43+对Eu3+的敏化效率提高。对（Y,Gd）VO4：Eu3+中的能量传递过程进行分析认为，（Y,Gd）vo4：Eus＋中可能存在着VO_4~(3-)→Eu~(3+)和VO_4~(3-)（vuv）→Gd~(3+)→VO_4~(3-)（UV）→Eu~(3+)等几种能量传递方式，Gd3＋起着能量传递中间体的作用。（4）首次采用水热法合成了Y（P，v）O4：Eu3"红色荧光粉，发现初始体系pH为12.5、在240℃下反应6天可以得到Y（P，V）o4：Eu3＋纯相。结合XRD和SEM分析发现Y（P，V）O4：Eu3＋荧光粉的粒径随VO3-4浓度的增大而增大，YPO4：Eu3+的粒径为100-150nm，而YVO4：Eu3+的粒径则为400-450nm。对水热法合成的Y（P， V）O4:Eu3+的VUV光谱进行研究发现基质对Eu3+的敏化效率随VO3-4户含量的增多而提高。通过比较发射光谱中~5D_0→~7F_2与~5D_0→~7F_1跃迁的强度发现二者强度之比随VO_4~(3-_浓度的增大而增大，说明荧光粉的色纯度随VO4含量的增多而更好。比较水热法和高温固相法合成的Y（P，V）O4：Eus"的VUV光谱发现水热法制备的荧光粉在真空紫外区的吸收较弱，说明水热法制备的荧光粉虽然粒度较小，形貌规则，但发光性能不如高温固相法制备的Y（P,V）O4：Eu3＋荧光粉。（5）分别采用水热法和高温固相法制备了单掺稀土发光离子的LaBSIOS，并对它们的光谱性质进行了研究。通过比较产物的SEM照片发现水热法可以制备出粒度为2-3μm，形状近似于球形的产物，而高温固相法制备的样品形貌不规则，粒度分布范围广。对水热法制备的LaBSiO_5：Eu~(3+)进行红外光谱分析发现1300-400cm~(-1)范围内为BO_4基团和SiO_4基团的振动峰。首次对高温固相法制备的LaBSiO_5:Re~(3+)（RE=Eu，Sm，Th）的vuv光谱性质进行了分析，认为其VUV光谱中125-200nm范围内存在着BO_4基团的吸收带（125-165nm）和SiO4四面体的吸收带（165-183nm）。比较两种方法制备的荧光粉的光谱性质和亮度发现两种方法制备的荧光粉光谱性质基本一致，而水热法制备的LaBSiO_5：RE~(3+)（RE＝Eu，Sm，Tb）在254nm紫外光激发下亮度相对较低。

CA-100萃取稀土及二价金属的热力学和动力学研究

该文系统研究了一种新型有机羧酸类萃取剂仲壬基苯氧基乙酸(CA-100)对稀土及其杂质的萃取热力学和动力学规律,并通过协同萃取、双溶剂萃取、加入络合剂等手段对CA-100萃取体系进行改善,为该萃取剂在工业上的应用打下基础,具体的研究内容如下:1.研究了CA-100对于稀土及Zn,Cd,Cu,Co,Ni,Mn,Mg等金属元素的萃取热力学规律,计算了金属间分离系数,获得了萃取平衡方程式,考察了反萃性能及稀释剂和甲庚醇的加入对萃取的影响.研究发现该萃取剂可用于Sc同其它稀土的分离及某些金属对的分离,在很多方面优于环烷酸体系.2.探讨了CA-100与—盐基磷(膦)酸类萃取剂对锌和镉的协同萃取,研究了协同萃取机理,确定了协萃配合物的组成.3.研究了在络合试剂的存在下CA-100萃取重稀土的行为及Y同重稀土的分离情况.4.用恒流层界面池研究了CA-100萃取Y,Yb,La的萃取动力学,考察了各因素对萃取速率的影响,获得了萃取速率方程,探讨了动力学机理.5.探讨了各种因素对CA-100界面活性的影响.6.在上述热力学和动力学研究基础上,进行了CA-100从混合稀土溶液中富集和纯化Sc的工艺模拟实验.

华南沿海近100年来2月份的极端气温事件

采用IPCC AR4规定的极端天气事件划分标准，分析1908—2008年广州、香港、

INVESTIGATION OF THE GROWN DIAMOND (100) SURFACE USING HIGH-RESOLUTION ELECTRON-ENERGY LOSS SPECTROSCOPY

The diamond (100) facets deposited at initial 1.0% CH4 have been investigated using high resolution electron energy loss spectroscopy (HREELS). The diamond (100) facets grown at 800-degrees-C are terminated by CH2 radicals, and there is no detectable frequency shift compared with the characteristic frequencies of molecular subgroup CH2. Beside the CH2 vibration loss, CH bend loss (at 140 meV) of locally monohydrogenated dimer is detected for the diamond (100) facets grown at 1000-degrees-C. Dosing the (100) facets grown at 800-degrees-C with atomic hydrogen at 1*10(-6) mbar, the loss peak at 140 meV appears. It is suggested that there are enough separately vacant sites and uniformly dispersed monohydrogenated dimers on (100) facets. This structure relaxes the steric repulsion between the adjacent hydrogen atoms during the diamond (100) surface growth.

ELECTRONIC SPECTROSCOPY STUDIES OF A P2S5NH4OH TREATED GAS(100) SURFACE

Microscopic characteristics of the GaAs(100) surface treated with P2S5/NH4OH solution has been investigated by using Auger-electron spectroscopy (AES) and x-ray photoemission spectroscopy (XPS). AES reveals that only phosphorus and sulfur, but not oxygen, are contained in the interface between passivation film and GaAs substrate. Using XPS it is found that both Ga2O3 and As2O3 are removed from the GaAs surface by the P2S5/NH4OH treatment; instead, gallium sulfide and arsenic sulfide are formed. The passivation film results in a reduction of the density of states of the surface electrons and an improvement of the electronic and optical properties of the GaAs surface.

Optical characterization of InAs monolayer quantum structures grown on (311)A, (311)B, and (100)GaAs substrates

Low-temperature photoluminescence and excitation spectra from InAs monolayer quantum structures, grown on (311)A, (311)B, and (100) GaAs substrates, are investigated, The structures were grown simultaneously by conventional molecular-beam epitaxy (MBE), The experimental results show that the quality of InAs monolayer on (311)B GaAs substrate is obviously better in crystal quality than those on the two other oriented GaAs substrates. In addition, the transition peaks of the InAs layer grown on (311) GaAs substrates shift to higher energy with respect to that from the InAs layer grown on (100) GaAs substrate.

New aspects of K promoted nitridation of the InP(100) surface

The effect of molecular nitrogen exposure on the InP(100) surface modified by the alkali metal K overlayer is investigated by core-level photoemission spectroscopy using synchrotron radiation. The alkali metal covered surface exhibits reasonable nitrogen uptake at room temperature, and results in the formation of a P3N5 nitride complex. Flash annealing at 400 degrees C greatly enhanced the formation of this kind of nitride complex. Above 500 degrees C, the nitride complex dissolved completely. (C) 1997 American Vacuum Society.

Structural ordering and interface morphology in symmetrically strained (GaIn)As/Ga(PAs) superlattices grown on off-oriented GaAs(100)

In this work we investigate the structural properties of symmetrically strained (GaIn)As/GaAs/Ga(PAs)/GaAs superlattices by means of x-ray diffraction, reciprocal-space mapping, and x-ray reflectivity. The multilayers were grown by metalorganic vapor-phase epitaxy on (001) GaAs substrates intentionally off-oriented towards one of the nearest [110] directions. High-resolution triple-crystal reciprocal-space maps recorded for different azimuth angles in the vicinity of the (004) Bragg diffraction clearly show a double periodicity of the x-ray peak intensity that can be ascribed to a lateral and a vertical periodicity occurring parallel and perpendicular to the growth surface. Moreover, from the intensity modulation of the satellite peaks, a lateral-strain gradient within the epilayer unit cell is found, varying from a tensile to a compressive strain. Thus, the substrate off-orientation promotes a lateral modulation of the layer thickness (ordered interface roughness) and of the lattice strain, giving rise to laterally ordered macrosteps. In this respect, contour maps of the specular reflected beam in the vicinity of the (000) reciprocal lattice point were recorded in order to inspect the vertical and lateral interface roughness correlation, A semiquantitative analysis of our results shows that the interface morphology and roughness is greatly influenced by the off-orientation angle and the lateral strain distribution. Two mean spatial wavelengths can be determined, one corresponding exactly to the macrostep periodicity and the other indicating a further interface waviness along the macrosteps. The same spatial periodicities were found on the surface by atomic-force-microscopy images confirming the x-ray results and revealing a strong vertical correlation of the interfaces up to the outer surface.

Ordering along <111> and <100> directions in GaInP demonstrated by photoluminescence under hydrostatic pressure

Photoluminescence of GaInP epilayers under hydrostatic pressure is investigated. The Gamma valley of disordered GaInP shifts sublinearly upwards with respect to the top of the valence band with increasing pressure and this sublinearity is caused by the nonlinear dependence of lattice constant on the hydrostatic pressure. The Gamma valleys of ordered GaInP epilayers rise slower than that of the disordered one. Considering the interactions between the Gamma valley and folded L and X valleys, the pressure dependence of the band gap of ordered GaInP is calculated and fitted. The results demonstrate that not only ordering along [111] directions but also sometimes simultaneous ordering along [111] and [100] directions can occur in ordered GaInP. (C) 1996 American Institute of Physics.