白光LED用GdVO_4:Eu~(3+)红色荧光粉的制备及性能

采用高温固相法制备了GdVO_4:Eu~(3+)红色荧光粉。通过X射线粉末衍射(XRD)、扫描电子显微镜(SEM)和光致发光光谱(PL)对样品的物相、形貌及发光性能进行了表征。结果表明:所合成的GdVO_4:Eu~(3+)红色荧光粉为四方晶系,表面为类球形。激发光谱中,位于382 nm、395 nm、418 nm和466 nm的激发峰分别归属于~7F_0→~5L_7、~7F_0→~5L_6、~7F_0→~5D_3及~7F_0→~5D_2跃迁。发射光谱中,位于593 nm、625 nm、654 nm和701 nm的发射峰对应Eu~(3+)的~5D_0→~7F_1、~5D_0→~7F_2、~5D_0→~7F_3及~5D_0→~7F_4跃迁。当Eu~(3+)掺杂量为7%,800℃煅烧8 h时,GdVO_4:Eu~(3+)红色荧光粉CIE色坐标为(0.6426,0.3530),荧光寿命为0.52 ms,是一种有望用于白光LED的高效红色荧光粉。     

(M,M′)O-Al_2O_3-SiO_2:Eu~(3+),Bi~(3+)的发光

用分析纯试剂经提纯制备的CaCO_3,SrCO_3,BaCO_3,Li_2CO_3,Al_2O_3,SiO_2,Bi_2O_3,Eu_2(C_2O_4)_3为原料,通过固态反应合成了(M,M′)_(1.920)O·0.1Al_2O_3·1.5SiO_2:Eu_(0.025)~(3+),Bi_(0.04)~(3+)(M,M′为Ca~(2+),Sr~(2+),Ba~(2+)中的任两种)系列发光材料。研究了基质的化学组成对Bi~(3+)敏化Eu~(3+)发光特性的影响规律。实验结果表明,激发Bi~(3+)时Eu~(3+)的发射谱线的分裂和~5D_0—~7F_2/~5D_0—~7F_1跃迁强度比值都受基质阳离子半径的较大影响。各组阳离子组合时Bi~(3+)都能敏化Eu~(3+)的发光。Eu~(3+)的发射以~5D_0—~7F_2跃迁为主,~5D_0—~7F_1跃迁强度较弱。     

Er~(3+)掺杂调控NaY(WO_4)_2:Dy~(3+)的上转换发光性能

采用水热法合成出Dy~(3+),Er~(3+)共掺杂NaY(WO_4)_2荧光粉。利用XRD和SEM对样品的晶体结构及形貌进行表征。研究了上转换发光性能和Dy~(3+)的~4F_(9/2)→~6H_(13/2)跃迁的荧光衰减曲线,并讨论了Dy~(3+)→Er~(3+)的能量传递过程。结果表明:所有合成的样品均具有NaY(WO_4)_2四方相结构;加入聚乙二醇(PEG-2000)作为表面活性剂,可得到分散性良好的微米针状球;在780 nm近红外光激发下,观察到了480 nm蓝光、576 nm黄光、531 nm及554 nm绿光发射峰,其中蓝光和黄光分别来自Dy~(3+)的~4F_(9/2)→~6H_(15/2)与~4F_(9/2)→~6H_(13/2)跃迁,绿光发射由Er~(3+)的~2H_(11/2)→~4I_(15/2)和~4S_(3/2)→~4I_(15/2)跃迁产生。通过研究荧光光谱和荧光衰减曲线,证实了Dy~(3+)→Er~(3+)的能量传递过程,且该能量传递的机制为电偶极–电偶极相互作用。通过调节NaY(WO_4)_2:1.0mol%Dy~(3+),xmol%Er~(3+)荧光粉中Er~(3+)的浓度,可实现由准白光到蓝光的转变。     

Na(Y_(1.5)Na_(0.5))F_6∶Eu~(3+)的热稳定橙色发光及荧光增强

采用简单的水热工艺制备了六方相Na(Y_(1.5)Na_(0.5))F_6∶Eu~(3+)荧光粉。300K温度下利用394nm光波长激发,观察到Eu~(3+)的~5D_n(n=0,1,2)→~7F_J(J=1,2,3,4)跃迁,对应主波长590nm,色彩饱和度约为0.97。当温度升高到420K时,仅观察到微小的色漂移。进一步拟合Ln(I_0/I-1)和10 000/T的关系曲线,确定发光的热猝灭激活能约为0.324eV。良好的热稳定性,表明Na(Y_(1.5)Na_(0.5))F_6∶Eu~(3+)适合于功率器件的封装。在Na(Y_(1.5)Na_(0.5))F_6∶Eu~(3+)表面包覆二氧化硅后,可观察到Eu~(3+)增强的发光,但这种荧光增强依赖于二氧化硅壳层的厚度。利用荧光增强与荧光猝灭的竞争模型解释了上述现象。     

近紫外白光LED用Ca2-xSiO3Cl2∶xEu3+高效红色荧光粉的发光性能研究

采用传统的高温固相反应法在较低温度下制备红色荧光体Eu~(3+)掺杂的Ca_2SiO3_Cl_2,研究了Ca_(2-x)SiO_3Cl_2∶xEu~(3+)(x=3%～18%)的晶体结构和发光性质。激发和发射光谱表明,样品可以被近紫外350～420nm波段激发,最强激发峰位置位于394nm,发射光谱呈现出Eu~(3+)的特征红色发光,谱带峰值位置在592nm和620nm,分别对应于~(5 )D_0→~7F_1和~(5 )D_0→~7F_2特征跃迁。结果表明:最强发射对应的掺杂浓度是15%(摩尔分数),样品Ca_(1.85)SiO_3Cl_2∶0.15Eu~(3+)荧光粉是一种具有应用潜力的近紫外激发三基色白光LED用红色荧光粉。     

层层浸渍法制备Eu3+∶KY(WO4)2薄膜及其发光性能研究

采用层层浸渍法制备石英玻璃基铕离子(Eu~(3+))∶钨酸钇钾[KY(WO_4)_2][(Eu~(3+))∶KY(WO_4)_2]薄膜。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、荧光光谱仪和原子力显微镜进行表征。结果表明:薄膜由Eu~(3+)∶KY(WO_4)_2单斜晶体组成,薄膜表面粗糙度Ra=22.343nm,在262nm激发光下可发射614nm(Eu~(3+)离子~5D_0→~~7F_2跃迁)的红光,其中262nm处为钨酸根离子中的O→W的电荷转移而产生的光波段,说明WO_4~(2-)子与Eu~(3+)之间存在能量传递,614nm处的荧光寿命是0.98ms。     

SrZn(WO_4)_2∶Eu~(3+)红色荧光粉的合成及性能研究

用共沉淀法制备了适合于近紫外激发的红色荧光粉掺铕钨酸锌锶[SrZn(WO_4)_2∶Eu~(3+)],通过X射线衍射、荧光光谱对样品的结构及发光性能进行了表征。XRD分析表明样品的主衍射峰与标准卡片(JCPDS 08-0490和JCPDS15-0774)的衍射峰基本一致,说明掺杂Eu~(3+)未改变基质晶格结构。在样品的激发光谱中,394nm为主激发峰,属于Eu~(3+)的f-f跃迁吸收。在波长为394nm的紫外激发下,样品发射主峰位于616nm,归属于Eu~(3+)的~5D_0→~7F_2跃迁。当Eu~(3+)掺量为7%(mol,摩尔分数)时,样品的发光强度达到最大。     

棒状LaVO4∶Dy3+纳米晶的水热合成及荧光性能研究

以La_2O_3、Dy_2O_3、浓HNO_3、偏钒酸钠、氢氧化钠、无水乙醇、乙二醇为原料,采用十六烷基三甲基溴化铵(CTAB)辅助水热法合成了四方晶系锆石结构的LaVO_4∶Dy~(3+)棒状纳米晶体。并用X粉末衍射(XRD)、扫描电镜(SEM)、红外光谱(FT-IR)和荧光光谱(FL)对产品进行了表征和分析。测试结果表明,所得样品为四方锆石型结构,反应pH从7升至10,纳米棒增长60～70nm。LaVO_4∶Dy~(3+)纳米棒分别在574nm和484nm处有较强的黄光发射(~4F_(9/2)→~6H_(13/2))和蓝光跃迁(~4F_(9/2)→~6H_(15/2)),通过改变反应的pH和Dy~(3+)掺杂量达到对黄蓝光强度比值(Y/B)的有效调控,Y/B值最大达1.207。     

Eu3+掺杂的钼酸盐微纳米材料制备和光致发光性能研究

分别采用沉淀法和水热法成功制备了Y_2(MoO_4)_3∶Eu~(3+)红色荧光粉,使用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)和荧光光谱对其物相结构、形貌和发光性能进行表征。结果表明:Eu~(3+)含量低于20%(摩尔分数,下同)不会改变Y_2(MoO_4)_3的晶体结构;沉淀法得到荧光粉呈花状,而水热法主要得到层层堆积结构的荧光粉;所制荧光粉的主激发峰和发射峰分别位于394和614nm,这是来自掺杂Eu~(3+)的f-f电子跃迁。Y_2(MoO_4)_3荧光粉中Eu~(3+)最佳摩尔分数为20%,当Eu~(3+)含量大于20%时,出现浓度猝灭现象,其5D_0→7F_2发光浓度猝灭机理是电偶极-电偶极相互作用。     

铕(Ⅲ)激活铌酸钇的发光

在使用Li_2So_4作助熔剂的条件下,由相应的氧化物高温合成了Y_(1-x)Eu_xNbO_4(0≤x≤0.30),研究了各试样的光致发光。254nm紫外光激发下的发射光谱包括两个部分:位于330～480nm的弱发射谱带,相当于NbO_4基团的电荷转移态跃迁发射;在535～720nm之间有5组锐线状发射光谱,分别归属于Eu~(3+)的~5D_1—~7F_j(j=1,2,3)和~5D_o—~7F_j(j=1,2,3,4)跃迁发射,其中主发射峰是位于612.7nm的~5D_o—~7F_2跃迁发射。~5D_o—~7F_2发射的激发光谱包括NbO_4基团电荷转移态的强激发带,和一些Eu~(3+)f—f跃迁弱激发锐线谱。随着Eu~(3+)浓度的增大,两种激发都逐渐增强,这表明光致发光过程中存在着能量由NbO_4→Eu~(3+)的传递。当Eu~(3+)浓度大于0.15mol时发生发光的浓度猝灭。     

差值法与比值法的误差修正效果比较研究及应用

差值法与比值法对不同测量系统的误差修正效果不一样.本文将两种方法的比较用一个比值来描述,并用推得的公式进行量化表示.在进一步的应用研究中,理论分析与实验数据相互印证,同时得到许多有益的结论,有助于全面掌握测量系统的误差来源,从而灵活选择各种修正方法以获得更加准确的测量结果.     

接收机测量谐波的方法及优缺点分析

本文提出了一种采用测量接收机HP8902A测量射频信号源谐波的方法,对该方法的特点及应用范围进行了分析与说明,并通过与常规的频谱分析仪测量谐波的方法进行比较,确定了该测量方法的可行性,可以用于没有频谱分析仪的情况下射频信源谐波的检定。     

三峡工程水电站压力管道和蜗壳技术结构型式的选择及论证

长江三峡水利枢纽工程建设中重大技术问题的决策是建立在大量科学试验和专家论证的基础上，三峡工程水电站压力管道和蜗壳技术结构型式的选择不仅是重大的技术经济问题，也是关系水电站长期运行问题，文章介绍了三峡工程水电站压力管道和蜗壳技术型式选择及决策。     

The Algebra of Geometric Impossibility: Descartes and Montucla on the Impossibility of the Duplication of the Cube and the Trisection of the Angle

Today we credit Pierre Wantzel with the first proof (1837) of the impossibility of doubling a cube and trisecting an arbitrary angle by ruler and compass. However two centuries earlier Descartes had put forward what probably counts as the first proof of these impossibilities. In this paper I analyze this proof, as well as the later related proof given by Montucla (1754) and the brief version of this proof published by Condorcet (1775) . I discuss the many novelties of these early arguments and highlight the problematic points addressed by Gauss (1801) and Wantzel. In particular I show that although Descartes developed many of the algebraic techniques used in later proofs he failed to provide an algebraic impossibility proof and resorted to a geometric argument. Montucla and Condorcet turned this proof into an algebraic one. I situate the analysis of the early proof of the impossibility of the two classical problems in the general context of early modern mathematics where mathematics was primarily viewed as a problem solving activity. Within such a paradigm of mathematics impossibility results arguably do not play the role of proper mathematical results, but rather the role of meta-results limiting the problem solving activity.     

A re-parameterisation of the Power Model of the relationship between the speed of traffic and the number of accidents and accident victims

This paper presents a re-analysis of the Power Model of the relationship between the mean speed of traffic and road safety. Past evaluations of the model, most recently in 2009, have broadly speaking supported it. However, the most recent evaluation of the model indicated that the relationship between speed and road safety depends not only on the relative change in speed, as suggested by the Power Model, but also on initial speed. This implies that the exponent describing, for example, a 25% reduction in speed will not be the same when speed changes from 100 km/h to 75 km/h as it will when speed changes from 20 km/h to 15 km/h. This paper reports an analysis leading to a re-parameterisation of the Power Model in terms of continuously varying exponents which depend on initial speed. The re-parameterisation was accomplished by fitting exponential functions to data points in which changes in speed and accidents were sorted in groups of 10 km/h according to initial speed, starting with data points referring to the highest initial speeds. The exponential functions fitted the data extremely well and imply that the effect on accidents of a given relative change in speed is largest when initial speed is highest.     

聚酰亚胺薄膜增塑形变的结构与性能研究

采用带柔性基团的4,4’-二氨基二苯醚（ODA）和均苯四甲酸二酐（PMDA）为单体用两步法合成聚酰亚胺（PI）。合成过程中,在中间产物聚酰胺酸中加入离子液体（IL）将高分子链阻隔开来,然后再对其进行酰亚胺化得到PI／IL杂化材料．对杂化材料进行热拉伸,然后水洗除去IL,再进行热拉伸致密化处理得到最终的PI。利用动态力学分析（DMA）、红外（IR）、拉伸、和x衍射（XRD）等时材料的微观结构和力学性能进行了研究。结果表明,经离子液体增塑后,PI的拉伸强度提高了3倍,取向度由无取向提高到60％。     

论知觉对象与背景的关系

通过将"万绿丛中一点红"中的哲学原理在广告的创意、制作中的运用得到的经验,阐述了这样的原理:知觉对象与背景是通过对比与协调达到和谐统一的,它们通过色彩与造型的差异性和互补性,产生奇特的视觉效果,给人以鲜明的印象和强大的视觉冲击力,从而达到吸引消费者的目的.这在广告学中有着至关重要的作用,也是众多广告设计中都遵守的原则之一.     

History of the Korean GLPs and the activities and perspectives of the Korean Society of GLP.

The Korean Society of Good Laboratory Practice (KSGLP) was established Dec. 10, 1998. The objectives of the KSGLP are to enhance the quality of domestic studies and the level of GLP compliance, in safety testing, and to promote information exchange among its members. The activities of KSGLP include: offering workshops and symposiums, linking with related governmental organizations, collecting GLP related information and providing the information to the related organizations, building international networks to collect information and to establish relationship, developing training materials and publishing periodicals, and other business necessary to achieve the objectives of the KSGLP. The KSGLP achieved its goals within a short period of time by offering workshops and symposia, and by providing important GLP related information in newspapers or via the KSGLP's internet homepage (www.ksglp.or.kr). The main role of the KSGLP will be to disseminate GLP technology nationwide. The KSGLP would like to help many labs that are preparing their facilities for GLP compliance. Further, the KSGLP is hoping to share GLP experiences with other members.