Ti3+在Sol-gel多孔磷光SiO2干凝胶中的发光

采用常规的Sol-gel工艺合成了Ti3+掺杂的多孔磷光SiO2干凝胶,Ti3+离子作为间隙离子存在于SiO2网络中,展示了一种新颖的发光现象,改变了Sol-gel SiO2干凝胶的发射光谱.这种掺杂SiO2干凝胶的激发和发射光谱均由2个带组成,短波长的发光峰在440nm(λex＝380nm),其相对荧光强度约是纯SiO2干凝胶的5倍;长波长的发光峰在600nm(λex＝550nm),其相对荧光强度约是Ti3+掺杂ZnS纳米晶的20倍.由此可以得出:过渡金属离子掺杂的多孔磷光SiO2干凝胶形成了一类新型的发光材料.     

制备工艺条件对SiO2干凝胶发光性质的影响

系统研究了制备工艺条件对SiO2干凝胶发光性质的影响.结果显示:干凝胶的发光强度随着工艺参数的不同而变化.凝胶中的缺陷引发了蓝色和橙色发光.水和催化剂是凝胶制备过程中2个至关重要的工艺参数.加水量及催化剂加入量对干凝胶的网络结构影响很大,改变了SiO2干凝胶中发光的缺陷浓度,从而导致其发光强度的变化.     

Al3+-Ce3+共掺杂纳米SiO2的发光性能

采用溶胶-凝胶技术制备了Al3+-Ce3+共掺杂的纳米SiO2,并对其进行H2气氛中700～800℃的热处理.采用透射电子显微镜(transmission electron microscope,TEM)、Fourier红外光谱仪(Fourier transform infrared spectroscopy,FTIR)、紫外-可见分光光度计(ultraviolet-visible spectrophotometry,UV-Vis)及荧光光谱仪观察并测试掺杂改性纳米SiO2的形貌及光学性能.结果表明,掺杂纳米SiO2中存在两个起源小同的383nm发光带:一个为由245nm激发产生的383nm和402nm双峰结构的发光带.该发光起源于纳米SiO2的本征缺陷中心;另一个为由314nm激发产生的383nm宽带发光,该发光带起源于掺杂的Ce3+;并且研究了该发光带强度与Al3+的掺杂浓度以及热处理温度的关系.     

Mn2+在Zn2SiO4中的发光

利用Sol-gel法制备掺Mn^2 的Zn2SiO4的前驱体，并将前躯体在弱氧化气氛下在1000℃煅烧2h，得到掺Mn^2 的Zn2SiO4试样。X射线衍射分析确定试样为α-Zn2SiO4晶相。荧光分析测定试样的激发光谱和发射光谱。结果显示Mn^2 掺杂的α-Zn2SiO4可发蓝色和绿色荧光，这一结果显然不同于以前的文献报道。同时，我们讨论了Mn^2 在Zn2SiO4中产生这一新型发光性质的机理。     

多孔硅中的Er^3＋的离子发光增强

制备了注入能量为３５０ｋｅＶ，注入剂量为１×１０＾１２－１×１０＾１５ｉｏｎ／ｃｍ＾２的Ｅｒ＾３＋离子注入多孔硅样品。测定了退火后ＰＳ：Ｅｒ＾３＋的样吕的７７Ｋ红外光致发光光谱。     

纳米多孔SiO2微粉

多孔状纳米SiO2微粉的制备是以水玻璃的盐酸为原料，添加适定的稳定剂（非离了表面活性剂）在适宜的pH值和温度下沉淀合成，要得到性能优良的SiO2纳米微粉，最佳工艺的研究尤其重要，用BDL－B型电位仪，ET，EPMA－电子探针及DTA－TGA等手段对其性能进行表征，结果表明，制得的SiO2超细微粉，颗粒呈多孔状，具有巨大的比表面积，高达1000m2/g以上，孔径为25A左右，粒度分布均匀，粒度可达纳米级，这种粉末具有特殊的性能。     

多孔硅中的Er~（3＋）离子发光增强

制备了注入能量为３５０ｋｅＶ，注入剂量为１×１０￣（１２）～１×１０￣（１５）ｉｏｎ／ｃｍ￣２的Ｅｒ￣（３＋）离子注入多孔硅样品（简称ＰＳ：Ｅｒ￣（３＋）样品，下同）。测定了退火后ＰＳ：Ｅｒ￣（３＋）样品的７７Ｋ红外光致发光光谱。实验表明，ＰＳ：Ｅｒ￣（３＋）样品中的Ｅｒ￣（３＋）离子光致发光强度比Ｓｉ：Ｅｒ￣（３＋）样品中的Ｅｒ￣（３＋）离子强很多（数十倍），并且ＰＳ：Ｅｒ￣（３＋）样品中的Ｅｒ￣（３＋）离子发光峰更宽，次峰也更丰富。如果退火工艺进一步改进，ＰＳ：Ｅｒ￣（３＋）材料中１．５４μｍ光的发射强度将还能提高。     

影响多孔SiO2聚集体颗粒粒径的因素考察

在不考虑交互作用情况下，设计了五因素四水平正交实验以考察诸因素对硅灰石制多孔SiO2聚集体颗粒粒径的影响。实验结果表明，当反应时间统一为80min，陈化时间20min，反应温度50-55℃，所用酸为12MHCl。硅灰石用量为80g时，表面活性剂种类的选用对多孔SiO2聚集体颗粒粒径的影响最大，表面活性剂加入时间影响最小，多孔SiO2聚集体颗粒粒径最小的条件为悬浮液浓度20%，表面活性剂选用十六烷基三甲基溴化铵，体系最终pH值为1.5,NH4Cl添加量为1.25%。表面活性剂加入时间为60min时，验证实验结果符合这一结论。     

AI2O3-SiO2:Tb3+发光材料的溶胶--凝胶合成及发光特性

采用溶胶－凝胶（sol-gel)法低温合成了Al2O3-SiO2:Tb^3 绿色发光材料，研究了Al2O3和SiO2配比，Tb^3 浓,烧结温度，烧结时间对光强度的影响，讨论了发光体的发光特性。     

制备多孔SiO2的扩大实验及产品物性研究

在前期研究基础上，进行了硅灰石制备多孔SiO2的扩大实验。物性测试表明，所得产品SiO2含量为94.31%，比表面积达452.3m^2/g,DBP吸着率175m^2/g，PH值5.78-6.10，兰光白度87.80。亨特白度95.85，聚集体粒径D509.85um。与白炭黑质量国家标准相比，主要指标符合或超过标准，文章还对其应用进行了探讨。     

Photoluminescence Enhancement of SiO2‐Coated LaPO4:Eu3+ Inverse Opals by Surface Plasmon Resonance of Ag Nanoparticles

The surface plasmon resonance of Ag nanoparticles (NPs) and SiO₂ coating had been extensively employed to improve the photoluminescence (PL) intensity of nanomaterials. In the article, the LaPO₄:Eu³⁺ inverse opal photonic crystals were fabricated via combining a self‐assembly process with a sol–gel method. The SiO₂ shells were formed on the skeleton surface of LaPO₄:Eu³⁺ inverse opals and the Ag NPs were added into the voids of LaPO₄:Eu³⁺ inverse opals with the SiO₂ shells. The influence of the SiO₂ shells and Ag NPs on the PL of the LaPO₄:Eu³⁺ inverse opals were investigated. About sevenfold luminescence enhancement of LaPO₄:Eu³⁺ inverse opals was obtained by the coordination action of surface plasmon absorption effects of Ag nanoparticle and silica‐coating effects. The luminescence enhancement mechanisms of LaPO₄:Eu³⁺ inverse opals were discussed.     

Crystal structure and luminescence mechanism of novel Fe3+-doped Mg0.752Al2.165O4 deep red-emitting phosphors

Nonstoichiometric alumina-rich spinel provides diverse and changeable local environments for transition-metal dopants. In this contribution, novel Mg_0.752Al_2.165−xO₄:xFe³⁺ deep red-emitting phosphors were designed and prepared by the solid-state reaction method. The red emission presents an unexpected shift from 735 to 770 nm by comparing with Fe³⁺-doped MgAl₂O₄. The excitation spectrum of Mg_0.752Al_2.165−xO₄:xFe³⁺ is broadened in the UV region with a new strong peak at 320 nm. The crystal structure refinement and NMR spectra fitting reveal that the cation vacancies and disorder increase with excess Al³⁺ entering the spinel crystal lattice. According to the results of EPR, NMR, and PL/PLE measurements, it was proposed that the Fe³⁺ ions locate at the distorted octahedral coordination. The changes of the local structure of Fe³⁺ ions promote the doublet state's involvement in the d−d transition. It was proposed that the new excitation peak at 320 nm in Mg_0.752Al_2.165−xO₄:xFe³⁺ is associated with the transitions from the ground state ⁶A_1g(⁶S) to the ⁴A_2g(⁴F)/T_1g(⁴P) and doublet states. The transition between the lower energy excited state of ²T_2g(²I) and ⁶A_1g(⁶S) mainly contributes to the deep red emission and the red-shifting effect.     

Al3+/Bi4Ti3O12薄膜的制备及其光催化性能表征

采用溶胶一凝胶法制备了掺 Al3+ 的Bi4 Ti3 O12 薄膜(Bl-xAlxTi3O12).采用分光光度法研究了薄膜对甲基橙溶液的降解,以及Al3+对薄膜的光催化效果影响.光催化结果表明,Al3+的掺杂量为 2atm% 时,薄膜的光催化效果最好,比未掺杂前提高 57.9%,且吸收边红移量为 36nm.     

Photodarkening and anti-Stokes photoluminescence from PbSe and Sr2+-doped PbSe quantum dots in silicate glasses

Photoluminescence (PL) properties of PbSe and Sr²⁺-doped PbSe quantum dots (QDs) doped in silicate glasses were investigated by changing the excited laser wavelength and intensity. When BaO was replaced by SrO, the Sr²⁺-doped PbSe QDs formed and showed large blue-shifts in both absorption and PL bands compared to the PbSe QDs. It is attributed to the increasing in band gap resulted by the incorporation of Sr²⁺ ions into PbSe QDs. These two kinds of QDs were excited by the laser with the wavelengths of 1319 and 1532 nm. When rising the pumping intensity up to 1000 mW, the PL intensity from Sr²⁺-doped PbSe QDs monotonically increased, while, the PL intensity from PbSe QDs reached maximum at pumping intensity at ~200 mW (λ_ex = 1319 nm) and ~300 mW (λ_ex = 1532 nm). The good resistance to photodarkening of Sr²⁺-doped PbSe QDs is indicated passivation effect on the surface defects from Sr²⁺ ions doping. For Sr²⁺-doped PbSe QDs the anti-Stokes photoluminescence (ASPL) were observed when using both 1319 and 1532 nm excitation. The integrated intensity of the ASPL is linear with the excitation intensity, which indicates that the ASPL belongs to the phonon-assisted one-photon process. And the ASPL intensity as a function of excitation intensity shows a size dependence of the QDs.     

铜离子掺杂CsPbCl3量子点光学性能及稳定性探究

近年来,钙钛矿因其特殊的结构受到广泛的关注。其中,全无机钙钛矿量子点作为下一代发光材料更因其优异的发光性能得到了广泛的研究和关注。但是因为其本身的铅（Pb）元素带来的毒性和较差的稳定性,钙钛矿量子点在生产和应用方面依然面临着诸多阻碍。为了解决这些难题,介绍了一种铜离子（Cu²⁺）B位掺杂CsPbCl₃钙钛矿量子点。采用了热注射的方法成功地将Cu²⁺引入CsPbCl₃钙钛矿量子点中。研究发现,Cu²⁺掺杂CsPbCl₃量子点能够保持初始四方晶体结构。由于Cu²⁺的掺杂,有效地消除了CsPbCl₃量子点的表面缺陷,从而通过辐射途径促进了激子复合,提高了CsPbCl₃量子点的发光性质。通过稳定性对比测试发现,一段时间内,Cu²⁺掺杂CsPbCl₃量子点在水中的发光强度明显高于CsPbCl₃量子点。     

Er3+-doped CaF2 polycrystalline ceramic with perfect transparency for mid-infrared laser

Er³⁺-doped CaF₂ transparent ceramics are promising mid-infrared gain materials because of their utra-low phonon energy as well as excellent physical, chemical, and optical properties. However, existing hot-pressed and hot-formed CaF₂ ceramics are very difficult to be used in practical applications due to residual pores and weak polycrystallization, respectively. Here, we developed the high quality Er³⁺-doped CaF₂ transparent polycrystalline ceramic by single crystal ceramization. The sample exhibits obvious polycrystalline structure, good mechanical properties, perfectly transmittance, and excellent mid-infrared performance, which provides significant and wide-ranging opportunities for advanced mid-infrared gain materials.