基于硅酸盐体系白光LED用荧光粉的研究现状

以硅酸盐为基质的白光LED用荧光粉材料,具有良好的化学稳定性、热稳定性、合成工艺简单等优点,成为研究的热点.详细介绍了目前基于硅酸盐体系白光LED用荧光粉的研究现状,重点阐述了近年来二元硅酸盐、三元硅酸盐和其它硅酸盐荧光粉在制备、合成、发光性能方面的最新进展,最后展望了硅酸盐体系白光LED用荧光粉的制备工艺、发光性能以及新材料的开发.     

单一基质白光LED用荧光粉的研究进展

白光LED被称为第四代照明光源,具有广阔的应用前景。单一基质白光LED用荧光粉因其具有独特的优势而被广泛关注,研制单一基质白光LED用荧光粉具有十分重要的意义。详细介绍了目前国内外单一基质白光LED用荧光粉的研究进展,重点对硅酸盐、磷酸盐等几类单一基质白光LED用荧光粉的研究现状作了评述,指出了当前存在的问题,并展望了其发展前景。     

白光LED用碱土氯硅酸盐荧光粉的研究进展

稀土激活的碱土氯硅酸盐荧光粉是一类性能优良的发光材料,具有合成温度低、发光亮度高和化学性能稳定,且易被紫外-近紫外光高效激发等优点而获得了高度关注。从光谱性质和制备方法方面综述了目前国内外这一领域的研究进展,并指出了当前存在的问题及未来的研究重点和发展方向。     

近紫外光激发的白光LED用单基质硅酸盐荧光粉的研究进展

白光LED被称作第4代照明光源,有着庞大的应用市场.荧光粉光转换白光LED是当今固态照明的主流方案.研制近紫外光激发的白光LED用单基质硅酸盐荧光粉具有十分重要的意义.综述了目前国内外这一领域的研究进展,并指出了当前存在的问题及未来的发展方向.     

表面处理对LED用硅酸盐荧光粉性能的影响

采用溶胶-凝胶法,以正硅酸乙酯为原料对Sr3-xBaxSi O5:Eu发光二极管用荧光粉进行表面处理,分析表面处理对荧光粉的颗粒形貌、耐水性能、热猝灭性能的影响,并对荧光粉的封装应用性能进行研究。结果表明,表面处理使硅酸盐荧光粉的颗粒形貌发生较大改变,耐水性能以及热猝灭性能大大提高,初始发光强度提高约3%,封装后发光二极管的光衰点亮1 008 h后减少3%。     

日本Lumi-tech公司发布了一款用于白光LED产品的SSE荧光粉

日本Lnmi-tech有限公司已经开始了用于白光LED封装SSE（SSE，分子式：Sr3SiO5：Eu的缩写）荧光粉的销售。这种荧光粉使用硅酸盐体系制造，不含有像YAG的红色结构。     

Eu~(2+)激活的蓝光荧光粉研究进展

介绍了蓝光荧光粉的类型(主要为碱土铝酸盐型BaMgAl10O17,硅酸盐型,磷酸盐型及其硼酸盐型蓝光发光材料)及结构,总结了其研究现状与发光机制,概括了常规制备方法,指出了蓝光荧光粉存在的问题和今后研究与应用的方向。     

日本Lumi—tech公司发布了一款用于白光LED产品的SSE荧光粉

日本Lumi—tech有限公司已经开始了用于白光LED封装SSS（SSS，分子式：Sr3SiO5：Eu的缩写）荧光粉的销售。这种荧光粉使用硅酸盐体系制造，因而不含有像YAG的红色结构。     

白色发光二极管用蓝色荧光粉的研究进展

白色发光二极管(WLED)被称为第四代照明光源,应用前景十分广阔.概速了目前国内外WLED用蓝色荧光粉的研究进展,介绍了WLED用蓝色荧光粉的基质材料、制备方法、发光中心和掺杂离子等对WLED用蓝色荧光粉发光性能的影响,展望了该类荧光材料的发展研究趋势和应用前景.     

稀土Pr~(3+)激活白光LED用红色荧光粉的研究进展

开发高效的红色荧光粉是提高白光LED显色性、降低白光LED色温的关键因素。综述了稀土镨离子(Pr~(3+))激活白光LED用红色荧光粉的最新研究进展。介绍了Pr~(3+)作为激活剂的作用机理,并根据基质的分类,重点阐述了Pr~(3+)掺杂的硅酸盐体系、钨/钼酸盐体系、钛酸盐体系红色荧光粉的研究状况,归纳了Pr~(3+)激活的上述基质的发光特点。最后对该研究领域存在的问题、发展的方向分别进行了分析和展望。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

卧式金属罐容量的测量结果不确定度

本文根据多年的实践检定经验 ,参照JJF1 0 59- 1 999《测量不确定度评定与表示》以及《测量不确定度表达 1 0讲》 ,对卧式金属罐容量的测量结果不确定度进行了评定。     

盐酸浓度不确定度的评估

通过对盐酸浓度标定的过程分析，找出影响结果的各个分量，进行不确定度的评定，按照计量技术规范给出标准的表示法。     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Analysis of anisotropy of properties on the basis of studies of texture of coarse-grained ingots of thermoelectric materials

An analysis of anisotropy of the properties of a Bi₂Se_0.3Te_2.7 solid solution was carried out using construction of demonstrative surfaces for thermoelectric effectiveness and thermal expansion coefficients. It is shown that the texture is an important factor forming anisotropy of properties and technological fitness of ingots for manufacturing modules. Anisotropy of properties based on the studies of the ingot textures obtained using the float-zone method and Bridgman method (growing thermoelectric plates in a flat cavity) was studied.