上转换发光材料Na[Y0.57Yb0.39Er0.04]F4表面修饰醛基的研究

采用表面接枝改性法,以刚性分子对苯二甲醛为表面修饰剂,对上转换发光材料Na[Y0.57Yb0.39Er0.04]F4进行表面醛基修饰的研究.通过一系列的实验,确定优化实验条件为反应时间1.5h,缓冲溶液的pH值控制在9.5,修饰剂对苯二甲醛的加入量为0.010mol(氨基化材料的加入量为0.10g的前提下).在这种条件下,成功修饰在上转换发光材料表面的醛基量最高.并对修饰后材料的性能进行了表征,为其在荧光探针试验中的应用奠定了一定的基础.     

NaYF_4∶Yb~(3+),Er~(3+)上转换发光材料的葡聚糖表面改性及醛基化研究

采用"两浴-溶剂热法"制备了NaYF_4∶Yb~(3+),Er~(3+)上转换发光纳米粒子(UCNP),利用葡萄糖在苷化温度下置换UCNP表面的油酸,制得表面包被葡聚糖的亲水性UCNP。进一步通过NaIO_4氧化表面葡聚糖,获得了醛基化UCNP。采用TEM及光纤光谱仪等对修饰前后材料的形貌、发光特性进行了表征。优化实验表明0.5mol/mL葡萄糖在130℃下包被葡聚糖48h效果最好,包被后的UCNP在水相中分散良好且可在超过2个月内保持原有发光强度的75%。通过调节NaIO_4用量及氧化反应时间可以调控表面醛基修饰量。     

原位聚合法制备水溶性高聚物修饰的NaYF4：Yb,Er

采用原位聚合法,以聚丙烯酸（PAA）和聚乙烯吡咯烷酮（PVP）为壳层材料,对NaYF4上转换发光材料表面进行了PAA和PVP的修饰,傅立叶红外吸收光谱和热重分析证明了NaYF4纳米粒子表面有PAA和PVP的存在,透射电镜显示,当反应温度在0℃,丙烯酸单体含量为8.0wt%,反应时间130min时,PAA修饰的纳米粒子微观形貌最佳;当反应温度在60℃,乙烯基吡咯烷酮单体含量在12.0wt%,反应时间在150min的条件下,PVP修饰的纳米粒子微观形貌最佳。上转换荧光测试结果证明,在对材料进行NaYF4无机壳层包覆后再进行水溶性高聚物修饰,能够使其荧光性能保持不变。     

上转换发光材料及发光效率研究及展望

综述了上转换发光材料的进展.介绍了上转换发光的基本机制,较新的上转换发光材料,并分析了发光效率的影响因素.对上转换发光材料的发展进行了展望.     

通过热场和电场实现镧系离子掺杂铁电纳米复合材料上转换发光的可逆增强（英文）

调节镧系离子发光特性在传感、多彩显示、信息传递、防伪等领域具有重要意义.发光调控通常采用调控化学组分来实现,然而化学调控法不利于发展多模式检测、多重信息防伪等.本研究以镧系离子掺杂铁电纳米复合材料为研究对象,在热场和电场两种外部环境刺激下实现增强发光.在热场激励下样品呈现反猝灭现象,升温有效地增强了镧系离子的上转换近红外发光.同时基质中的铁电微晶晶格具有机电软弹性;通过电场调节镧系离子周围的晶体场结构实现了显著的发光增强,这种调控具有优异的可逆性和非易失性.本研究表明,可以通过热场和电场调控镧系离子掺杂多功能无机铁电体纳米复合材料的发光性质,这为设计高度集成的发光传感器件和智能设备提供了重要参考,特别是发展先进的多模式检测材料.     

多壁碳纳米管的γ辐射修饰

采用60Co-γ射线对多壁碳纳米管进行了辐射修饰.红外光谱分析(FTIR)表明,水中辐射没有在碳纳米管表面接枝上羧基;酸中辐射和干态辐射后用混酸处理都可以使碳纳米管接枝上羧基,但酸中辐射后的碳纳米管接枝上的羧基更多.拉曼光谱分析(Raman)表明,酸中辐射使碳纳米管的IG/ID值降低,使碳纳米管的石墨化程度降低,结构变得不完善.且辐射剂量越大,石墨化程度降低得越厉害,结构越不完善.热重分析(TGA)表明,原始碳纳米管是一步分解,酸中辐射修饰后的碳纳米管是两步分解.且辐射剂量越大,碳纳米管的起始热分解温度越低.     

Er3+掺杂的氧化钇纳米材料上转换发光性质的研究

利用燃烧法制备了稀土Er3 离子掺杂的氧化钇纳米晶材料.用JEM3010测量这种材料的结构与样品颗粒的分布,结果表明:晶粒尺寸约为30nm.用日立F-2500荧光光谱仪与978nm LD测量了该材料的上转换发光,得到该样品主要发绿色上转换发光,红色上转换发光非常弱.我们认为,这种现象与基质材料的低的声子能量与低的掺杂浓度有关.     

上转换发光材料的合成与应用

综述了目前国内外上转换发光材料的几种合成方法,包括传统的高温固相合成法、溶胶一凝胶法、水热合成法、共沉淀法等.总结了不同方法的优缺点,对上转换材料合成方法的发展进行了展望.并介绍了上转换技术的一些应用.     

有机分子表面修饰SrAl_2O_4∶Eu~(2+),Dy~(3+)荧光粉杂化材料研究进展

铕、镝共掺杂的铝酸锶(SrAl_2O_4∶Eu~(2+),Dy~(3+))无机荧光粉是一种重要的发光材料,将其与有机分子相结合有望成为具有卓越性能的新型光电功能材料。概述了有机分子表面修饰/SrAl_2O_4∶Eu~(2+),Dy~(3+)杂化材料的研究进展,重点介绍了杂化材料的制备及发光性质等,并简要展望了这类材料的发展前景。     

羧基功能化和表面活性剂修饰对石墨烯电化学性能的影响

通过简单的两步溶液法对石墨烯进行羧基接枝和表面活性剂修饰, 并研究其电化学性能。研究结果表明, 与纯石墨烯(比电容50 F/g)相比, 表面活性剂本身并不能有效提高石墨烯的比电容(45 F/g), 羧基功能化可以将石墨烯的比电容提高至130 F/g。而羧基功能化和表面活性剂修饰双处理工艺能够将石墨烯的比电容提高到230 F/g, 且经800次充放电循环后其比电容仍然具有95%的保持率, 表明该材料具有良好的循环稳定性。因此, 调控石墨烯的表面化学特性对提高其电化学性能具有重要的意义。     

上转换纳米材料及其在提高太阳能电池光电效率中的应用

上转换纳米材料在提高太阳能电池光电效率方面的应用主要通过提高上转换纳米材料的发光性能来实现。利用上转换纳米材料能将2个或2个以上的低能短波光子转换成高能可见光的特性,可以拓宽太阳能电池对光的响应范围,达到提升光电转换效率的目的。主要介绍了上转换纳米材料,包括其发光机制与基质材料的选择。回顾了在近阶段主要使用的热分解法、水热法等制备方法,分析了其他一些制备方法。着重介绍了上转换纳米材料在晶体硅太阳能电池和染敏太阳能电池中的应用。从提升上转换材料发光性的角度来讨论对太阳能电池的研究,并指出了未来上转换纳米材料在太阳能电池中应用的研究重点是利用异质离子掺杂、表面等离子体耦合与量子点敏化等手段提升上转换效率,而染料耦联上转换纳米材料、上转换纳米材料壳包覆等方法也具有很大发展潜力。     

稀土上转换发光在钙钛矿太阳能电池中的应用

目前,钙钛矿太阳能电池最常使用的钙钛矿材料为CH_3NH_3PbI_3,其禁带宽度为1.55eV,导致低于该能量值的太阳光的光子无法被直接地吸收利用。因此,提高器件对太阳光谱的响应范围是提高钙钛矿太阳能电池性能的关键。稀土上转换材料可以将低能量近红外光转换为高能量可见光,所以,稀土上转换发光的应用是提高钙钛矿太阳能电池性能的较为可行的途径。本文概述了稀土上转换发光的基本机制,介绍了钙钛矿太阳能电池的结构和工作原理,综述了该太阳能电池的研究现状及其主要优势,重点阐述了稀土上转换发光在钙钛矿太阳能电池中的应用,最后对该太阳能电池的发展前景进行了展望。     

Optical properties and thermal degradation of CdSe capped with 3-mercaptopropionic acid

We have prepared different sizes of CdSe nanoparticles capped by 3-mercaptopropionic acid (MPA) utilizing different cadmium sources and different molar ratios of the starting precursors. The prepared nanoparticles possess different Se/Cd ratios and different quantity of capping molecules as elucidated by Energy dispersive X-ray spectrums analysis. Infrared analysis manifested that the two-function groups of MPA could coordinate to the surface of the nanoparticles core. Optical analysis revealed that the quantity of capping molecules coordinated to the surface of the nanoparticles have influence upon the absorption and emission spectra. The photoluminescence of the sample with a lot of the capping molecules at the surface of the nanoparticles displayed a band edge emission with narrow full width at half maximum, in addition to a small Stokes shift with coupling constant equal 1.2. Also the thermal analysis revealed that the coordination of capping molecule to the surface of the nanoparticles influence on their thermal degradation. On the other hand, we have tested the up-conversion luminescence for one of the prepared samples. The up-conversion luminescence displayed two emission bands with anti-stokes shifts.     

Layer-by-layer assembly of long-afterglow self-supporting thin films with dual-stimuli-responsive phosphorescence and antiforgery applications

The assembly of thin films (TFs) having long-lasting luminescence can be expected to play an important role in the development of new-generation smart sensors,anti-counterfeiting materials,and information-encryption systems.However,such films are limited compared with their powder and solution counterparts.In this study,by exploiting the self-organization of phosphors in the two-dimensional (2D) galleries between clay nanosheets,we developed a method for the ordered assembly of long-afterglow TFs by utilizing a hydrogen-bonding layer-by-layer (LBL) process.Compared with the pristine powder,the TFs exhibit high polarization and up-conversion room-temperature phosphorescence (RTP),as well as enhanced quantum yields and luminescence lifetimes,allowing them to be used as room-temperature phosphorescent sensors for humidity and oxygen.Moreover,modified day-based hybrids with multicolor RTP can serve as anti-counterfeiting marks and triple-mode 2D barcode displays.We anticipate that the LBL assembly process can be extended to the fabrication of other inorganic-organic room-temperature phosphorescent hybrids with smart luminescent sensor and antiforgery applications.     

Temperature dependence of up-conversion luminescence and photoluminescence of Mn2+ in ZnS:Mn2+ nanoparticles

The photoluminescence (excited at both 300 nm and 383.5 nm) and up-conversion luminescence (excited at 767 nm) of the Mn2+ 4T1-->6A1 transition in both bulk and ZnS:Mn2+ nanoparticles have been measured as a function of temperature. The Mn2+ emission spectra shift monotonically to longer wavelengths at lower temperatures, whereas the intensity change of the luminescence is more complex. The complicated temperature behavior is explained by considering the processes of nonradiation relaxation via phonon coupling, exciton thermal dissociation (binding energy), energy transfer, carrier trapping, and the temperature change of the absorption spectra. The fact that the temperature dependence of the 767 nm excited up-conversion luminescence is the same as the 383.5 nm excited photoluminescence in both bulk and nanoparticles supports the conclusion that the up-conversion luminescence is due to two-photon absorption.     

Carboxyl group functionalization of mesoporous carbon nanocage through reaction with ammonium persulfate

Carbon nanocage, a three dimensional cage type mesoporous carbon with very high surface area and pore volume, has been functionalized with carboxyl groups for the first time via a simple oxidation using ammonium persulfate solution (APS). The carboxyl groups functionalized carbon nanocage materials have been unambiguously characterized by various sophisticated instruments such as FT-IR, HRSEM-EDX, XRD, nitrogen adsorption, and HRTEM. The degree of carboxyl group functionalization has been controlled by the simple adjustment of the oxidation parameters such as oxidation time, APS concentration and oxidation temperature. FT-IR spectroscopy combined with the HRSEM-EDX has been used to provide a quantitative analysis of the carboxyl groups on the surface of the carbon nanocage materials before and after the APS treatment. In addition, the effect of the oxidation parameters on the structural order and the textural parameters of the carbon nanocage materials has been studied. It has been found that the role of oxidation parameters is highly critical to obtain carbon nanocage materials with a high density of carboxyl groups without affecting the structural order and the pore parameters. Thus, the reaction parameters have been carefully optimized and the best condition for the preparation of carboxyl group functionalized carbon nanocage with well-ordered structure has been proposed.     

Er~(3+)/Yb~(3+)共掺SrF_2纳米晶的溶剂热合成及发光性能研究

采用溶剂热方法制备得到了Er3+和Yb3+共掺杂的SrF2纳米晶,并对其上转换发光性能进行了研究.X-射线衍射结果表明所制备的产物为纯的SrF2.随着溶剂热温度的升高,该纳米晶衍射峰的强度逐渐增强,且与SrF2的标准衍射峰相比,所有衍射峰均向高角度偏移.TEM的结果表明,溶剂热处理后,SrF2颗粒的分散性得到明显改善,且晶粒大小随着溶剂热温度的升高而增大.在980nm激光泵浦下Er3+和Yb3+共掺杂SrF2纳米晶仅能观察到弱的上转换发光,而在500℃和600℃热处理2h后,其上转换发光强度明显增强.上转换发光强度与泵浦功率的关系表明绿光和红光均为双光子吸收过程.     

Surface nucleation and independent growth of Ce(OH)<Subscript>4</Subscript> within confinement space on modified carbon black surface to prepare nano-CeO<Subscript>2</Subscript> without agglomeration

Highly dispersed negative carboxyl groups can be formed on carbon black (CB) surface modified with strong nitric acid. Therefore positive cations can be uniformly absorbed by carboxyl groups and precipitated within a confinement space on modified CB surface to prepare highly dispersed nanomaterials. In this paper, the formation and dispersion status of surface negative carboxyl groups, adsorption status of Ce³⁺, surface confinement nucleation, crystallization and calcination process were studied by EDS, SEM, and laser particle size analysis. The results show that the carboxyl groups formed on modified CB surface are highly dispersed, and Ce³⁺ cations can be uniformly anchored by carboxyl groups. Therefore, highly dispersed Ce³⁺ can react with OH^? within a confinement surface region to form positive nano-Ce(OH)₄ nuclei which also can be adsorbed by electrostatic attraction. After independent growth of Ce(OH)₄ without agglomeration, highly dispersed CeO₂ nanoparticles without agglomeration can be prepared together with the help of effectively isolates by CO₂ released in the combustion of CB.