GaAlAs三元化合物的喇曼散射

我们用He-Ne和Ar~+激光器的各条分立谱线,对各种组份下的三元化合物Ga_(1-x)Al_xAs(1>x>0.2)的喇曼散射以及无序效应进行了研究。由于Ga-As,Al-As之间的相互作用较强,使得GaAlAs成为典型的双模混晶。首先我们测量了声子频率随组份的变化。为同时观察到了TO,LO模,我们采用直角散射,考虑到折射率的影响,计算了此时喇曼散射的效率。分析了两种无序激活的声学声子DATA和     

Study on UV Excitation Properties of Eu^3＋ at S6 Site in Bulk and Nanocrystalline Cubic Y2O3

Increases of emission intensities for Eu^3 at the S6 site relative to that at the C2 site were observed as UV excitation wavelength decreases from 300 nm to 200 nm in both bulk and nanocrystalline cubic Y2O3:Eu^3 . Decomposition of excitation spectra shows that the charge transfer band of Eu^3 at the S6 site lies in the high-energy side of that at the C2 site, resulting in that the energy transfer from the host prefers to the S6 site. Detailed emission and excitation spectral characteristics were analyzed and discussed. In addition, spectral red-shift were found in both charge transfer bands in nanocrystalline Y2O3: Eu^3 compared to the bulk material. The number ratio of S6 sites to C2 sites is also smaller in nanocrystalline Y2O3:Eu^3 than that in the bulk one.     

A green-yellow emitting β-SreSiO4：Eu^2＋ phosphor for near ultraviolet chip white-light-emitting diode

Sr2SiO4：xEu^2＋ phosphors were synthesized through the solid-state reaction technique. The crystal phase of Sr2SiO4：xEu^2＋ phosphor manipulated by Eu^2＋ concentration was studied. The phase transited from β to α＇ in Sr2SiO4：xEu^2＋ phosphor with increasing europium concentration. The single β phase was formed as x≤005 and changed α＇ phase when x〉0.01. The emission spectrum of the β-Sr2SiO4：Eu^2＋ phosphor consisted of a green-yellow broadband peaking at around 540 nm and a blue band at 470 nm under near ultraviolet excitation. The white LEDs by combining near ultraviolet chips with β-Sr2SiO4：Eu^2＋ phosphors were fabricated. The luminous efficiency （15.7lm/W） was higher than α＇-Sr2SiO4：Eu^2＋ phosphor white LED.     

Ga_(1-x)Al_xAs Raman散射的共振和反共振

本文着重研究了Ⅲ—Ⅴ族混晶半导体Ga_(1-x)AlAs Raman谱在不同温度下的多级共振行为。分析了二级及多级声子谱增强及产生的物理原因,从一个新的侧面证实了激子-LO声子复合体作为Raman散射中间态存在的可能性。同时,还从Raman散射张量出发,对近共振条件下TO声子的消失进行了讨论。     

Photon Cascade Emission through Energy Transfer in Pr^3＋and Er^3＋Codoped System

Energy transfer processes in Pr^3 -codoped CaAl12O19crystal from 12 to 290K were studied.Energy transfer from Pr^3 toEr^3 ions in this system was observed,The transfer can partially convert the ^1S0UVfluorescence of Pr^3 into green emission of the characteristic of Er^3 ,The efficiency of the energy transfer was estimated based of the spectroscopic data,The temperature dependence on the transfer was also discussed.     

Eu3 ,Li 共掺杂ZnO:Zn荧光粉的制备及发光性质

在还原气氛下利用高温固相反应法制备了Eu3 ,Li 共掺杂的ZnO:Zn 荧光粉.在近紫外光激发基质条件下,该荧光粉材料具有强的来自Eu3 的4f组态内跃迁线状发射及来自基质缺陷相关的绿色可见宽带发射.测量了稳态光谱,漫反射及时间分辨光谱以研究该材料的发光性质及基质向稀土离子的能量传递过程.在还原气氛下因在导带下形成了一系列浅施主能级,暂时储存激发能,施主中心浓度增加使得基质向稀土离子的能量传递效率增强.通过与纯Eu2O3粉末的光谱对比分析,确定了在此材料体系中存在处于两种局域环境的Eu3 .由于在近紫外区的强且有效的吸收,此材料有望成为应用于近紫外激发发光二极管的新型荧光粉.     

Spectroscopy of Pr^3＋4f5d Configuration in LaF3 Nanocrystals／Oxyfluoride Glass Ceramics

Theinterestofinvestigatingthe 4fn -15delectronicconfigurationofthetrivalentrareearth (RE)ionsisbasedonavarietyofapplicationsinthevacuumultra violet (VUV)regionofthespectrum ,suchasthede velopmentofplasmadisplaypanelsandmercury freefluorescenttubes[1] .Amo…     

施工企业项目经营管理

随着我国建筑市场经济体制的建立与发展,施工企业逐步走向市场,发展前景更为广阔。同时,建筑企业市场竞争也日趋激烈,要想在建筑市场立于不败之地,就要看谁在竞争中能夺取承包工程,并在日后施工中能优质,快速而成本又较低地完成施工项目,只有这样,施工企业才能获得一定的经济效益,赢得业主的认同。如何趋利避害．解决问题,是项目经营管理的主要职责。     

Preparation and Optical Properties of Er^3＋-Doped Gadolinium Borosilicate Glasses

Er3 -doped Gd2 O3 -SiO2 -B2 O3 -Na2O glasses were prepared, and formation range of glass of Gd2 O3 -SiO2 -B2O3 system was experimentally obtained. It is found that the glass phase can be formed only when the content of SiO2 is 0～50%(molar fraction), Gd2O3 is 0～30%(molar fraction) and B2 O3 is above 20%(molar fraction) in this glass system. The glass can also be obtained but becomes translucent at the contents of 60%(molar fraction) SiO2 and 30% Gd2O3 , or at the contents of 60%(molar fraction) SiO2 and 30%(molar fraction) B2O3. There is no glass phase formed in other glass components. Glass forming ability for Gd2O3 content of 10%, was characterized by the value of β, the parameter of crystallization tendency, which is 0.32～1.76, obtained from the differential thermal analysis. The absorption and emission cross section, the J-O parameters Ωt(2,4,6) and radiative transition probabilities were calculated by using the theory of McCumber and Judd-Ofelt. The emission properties at 1.5 μm of the samples are discussed with the product of full width at half maximum and stimulated emission cross section. It can be seen that the value of the FWHM×σepeak product in the prepared glass is more than those of germanate, silicate and phosphate glasses. Furthermore, the maximum value of the product among these glasses reported in this work is close to that of oxyfluoride silicate glass. Therefore, the Er3 -doped gadolinium borosilicate glass in this paper is a candidate for broadband erbium doped fiber amplifiers.