共查询到18条相似文献,搜索用时 94 毫秒
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以三乙二醇为表面配体,利用沉淀法制备了β-Ga_2O_3∶Cr~(3+)近红外(NIR)长余辉纳米颗粒.考察了反应条件对β-Ga_2O_3∶Cr~(3+)的发光性能和晶体结构的影响,并初步探讨了其NIR余辉发光机理.结果表明,当溶液的p H值为7,煅烧温度为700℃时,可获得高纯度的β-Ga_2O_3∶Cr~(3+)纳米颗粒,其平均粒径为30 nm,最大余辉发射波长可调控为750 nm,NIR余辉发光时间长于384 h.本方法得到的β-Ga_2O_3∶Cr~(3+)长余辉纳米颗粒不仅尺寸小,而且NIR余辉时间长,发射波长可调控,在低背景噪音的深组织活体成像中具有潜在的应用前景. 相似文献
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采用乙二醇辅助共沉淀法制备了小尺寸Cr,In共掺杂MgGa2O4(MGO∶Cr, In)近红外长余辉发光纳米粒子(Persistent luminescence nanoparticles, PLNPs), 并考察了Cr, In共掺杂及煅烧温度对MGO晶体结构、 余辉发光性质和尺寸的影响. 结果表明, 最优Cr, In共掺杂浓度分别为0.3%和0.02%, MGO∶Cr, In晶体属于Fd3m空间群, Cr, In共掺杂对纳米颗粒的结构无影响, 平均粒径为(8.61±2.23) nm, 分散性良好, 最佳煅烧温度为700 ℃. 并且, In掺杂可有效延长其余辉发光寿命, 平均发光寿命(τav)从49.33 s增大至52.89 s; 荧光量子产率增高至44.9%; 活化能Ea为(0.36±0.04) eV, 具有良好的热稳定性; 陷阱深度为0.696 eV. 此外, 该PLNPs分别在260 nm、410 nm和600 nm处有激发峰, 表明UV光、 蓝绿光以及红光皆可实现对其的激发, 发射波长皆位于705 nm处, 属于Cr3+的2E(2G)→4A2(4F)跃迁. 该PLNPs在红色LED灯、 光学储器件以及生物医学等领域具有巨大潜在应用价值. 相似文献
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采用水热-均匀共沉淀法制备了纳米SrAl2O4:Eu2+,Dy3+长余辉发光材料.通过XRD、TEM、荧光光谱、热释光谱对其结构和性能进行分析.XRD结果表明所制备的SrAl2O4:Eu2+Dy3+纳米发光材料为单相,属单斜晶系.TEM测试表明纳米SrAl2O4:Eu2+,Dy3+发光材料为规则的球状粒子,粒径为50~80 nm,且分散性良好.激发和发射光谱测试表明,样品的激发光谱是峰值在356 nm 的连续宽带谱,发射光谱是峰值位于512 nm的宽带谱,与SrAl2O4:Eu2+,Dy3+粗晶材料相比,激发和发射光谱都出现了"蓝移"现象.样品的热释光峰值位于358 K,适合于产生长余辉. 相似文献
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采用凝胶-燃烧法合成了系列稀土离子掺杂的Sr0.94MgSi2O6:Eu0.022+,Ln0.043+(Ln=La,Ce,Nd,Sm,Gd,Dy)蓝色长余辉发光材料,用X射线粉末衍射(XRD)、扫描电镜(SEM)、荧光分光光度计等对合成产物进行了分析和表征.结果表明:掺杂了不同稀土离子的SrMgSi2O6:Eu2+,La3+的晶体结构均为网方品系结构;其激发、发射光谱的峰形、峰位基本无变化,激发光谱为一宽带,最大激发峰位于400 nm处,次激发峰佗于415 nm处,发射光谱也为一宽带,最大发射峰位于470 nm附近,是典型的Eu2+的4F5d_4f跃迁导致的,不同之处在于其激发光谱、发射光谱强度及余辉性质有所差别,其中Dy3+是最理想的共掺杂稀土离子,Sr0.94MgSi2O6:Eu0.022+Dy0.043+的余辉时间最长,可达4 h;而Sm3+最差,Sr0.94MgSi2O6:Eu0.022+,Sm0.043+的余辉亮度最低,余辉时间最短. 相似文献
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利用硝酸铝、硝酸锶/硝酸钡、尿素为原料,以一定比例H2O/正丁醇/CTAB的混合液作传递压力的介质进行反应,然后将得到的前驱体在还原气氛下高温煅烧,得到亮度高、余辉时间长的MAl2O4∶Eu^2+,Dy^3+纳米结构长余辉发光材料。TEM测试表明,高温煅烧后得到的MAl2O4∶Eu^2+,Dy^3+均为棒状结构,其激发光谱和发射光谱均为宽带,主发射峰分别为513和498 nm,是典型的Eu^2+5d→4f跃迁。在对单掺Eu^2+与双掺Eu^2+,Dy^3+比较的过程中,明显发现双掺Eu^2+和Dy^3+的强度增加,且余辉增强。材料的余辉强度随时间的变化由最初的快减过程和随后的慢减过程组成,符合I=t^-1.1双曲线规律。该方法操作简单,在不同的温度和时间下均合成出了棒状MAl2O4∶Eu^2+,Dy^3+,不需球磨,可直接应用。 相似文献
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以巯基辛烷为表面配体, 通过调控Ag前体和Te前体的比例, 制备了第二近红外窗口荧光Ag2Te量子点. 采用透射电子显微镜(TEM)、 X射线衍射光谱(XRD)、 X射线光电子能谱(XPS)、 紫外-可见-近红外吸收光谱和荧光光谱等对产物进行了表征. 结果表明, 制得了粒径均一、 分散性好的油溶性Ag2Te量子点, 其最大荧光发射波长位于1320 nm, 荧光量子产率高达4.2%. 相似文献
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采用静电纺丝法制备了PVP/FeC6H5O7复合纳米纤维, 并将复合纤维在500 ℃高温烧结3 h, X射线衍射分析(XRD)表明, 烧结后的产物为正尖晶石结构的γ-Fe2O3晶体. 扫描电子显微镜(SEM)观测结果表明, 制得了直径均匀、 连续的复合纳米纤维, 其平均直径约为1000 nm; 烧结后的γ-Fe2O3纳米纤维保持了其连续性, 但纤维发生了收缩, 直径较烧结前小, 平均约为600 nm. 比表面积分析表明, γ-Fe2O3纳米纤维比表面积为57.18 m2/g. 气敏性能测试结果表明, 230 ℃为γ-Fe2O3纳米纤维检测丙酮气体的最佳工作温度. 在此温度下, γ-Fe2O3纳米纤维对丙酮气体表现出高响应度[S=6.9, c(Acetone)=7.88×104 mg/m3]和线性度(7.88×102~1.58×105 mg/m3浓度范围内). 同时, γ-Fe2O3纳米纤维气体传感器件还表现出良好的长期稳定性. 相似文献
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Cobalt oxide(C0304) with different morphologies was achieved by a simple solution-based method. Various parallel experiments show that several experimental parameters, such as the concentrations of NaOH and ethylene glyeol(EG), play important roles in the morphological controlling of C0304 nanoparticles. A lower concen- tration of NaOH favors quasi-spherical product with a uniform size of about 15 nm, whereas a higher concentration of NaOH generally leads to the formation of nanoplates with wide size distribution. In addition, C0304 nanorods were also obtained partially by introducing a certain amount of EG. A possible mechanism was proposed for the selective formation of C0304 with various morphologies. X-Ray diffraction(XRD), infrared(IR) spectrometry, scanning elec- tron microscopy(SEM), transmission electron microscopy(TEM) and UV-Vis spectrometry were used to characterize the samples. 相似文献
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以γ-环糊精(γ-CD)为主体, 采用饱和水溶液法对客体二甲戊灵进行包合. 采用紫外光谱以等摩尔连续变化法确定包合物的包合比为1∶1; 红外光谱证明二甲戊灵的部分苯环结构可能进入了γ-CD的空腔; 热分析结果证明包合作用提升了二甲戊灵的熔点; 粉末X射线衍射谱图中新衍射峰的出现说明形成了新物相; 扫描电镜则直观展现了包合物的外观. 以上结果均表明形成了γ-CD-二甲戊灵包合物, 其包合平衡常数K=1123.99 L/mol. 包合作用使二甲戊灵的熔点从54 ℃升至75 ℃, 溶解度提高了约11.5倍, 包合物热贮稳定性达标, 为进一步将其加工成其它水基化农药剂型提供了可能. 相似文献
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Dr. Zhangjun Hu Maria Ahrén Linnéa Selegård Dr. Caroline Skoglund Dr. Fredrik Söderlind Dr. Maria Engström Dr. Xuanjun Zhang Prof. Kajsa Uvdal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(38):12658-12667
Water‐dispersible and luminescent gadolinium oxide (GO) nanoparticles (NPs) were designed and synthesized for potential dual‐modal biological imaging. They were obtained by capping gadolinium oxide nanoparticles with a fluorescent glycol‐based conjugated carboxylate (H L ). The obtained nanoparticles (GO‐ L ) show long‐term colloidal stability and intense blue fluorescence. In addition, L can sensitize the luminescence of europium(III) through the so‐called antenna effect. Thus, to extend the spectral ranges of emission, europium was introduced into L‐ modified gadolinium oxide nanoparticles. The obtained EuIII‐doped particles (Eu:GO‐ L ) can provide visible red emission, which is more intensive than that without L capping. The average diameter of the monodisperse modified oxide cores is about 4 nm. The average hydrodynamic diameter of the L ‐modified nanoparticles was estimated to be about 13 nm. The nanoparticles show effective longitudinal water proton relaxivity. The relaxivity values obtained for GO‐ L and Eu:GO‐ L were r1=6.4 and 6.3 s?1 mM ?1 with r2/r1 ratios close to unity at 1.4 T. Longitudinal proton relaxivities of these nanoparticles are higher than those of positive contrast agents based on gadolinium complexes such as Gd‐DOTA, which are commonly used for clinical magnetic resonance imaging. Moreover, these particles are suitable for cellular imaging and show good biocompatibility. 相似文献
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以高效氯氰菊酯为芯材, 乙基纤维素为壁材, 采用溶剂蒸发法制备了微胶囊, 并对其理化性能进行表征, 通过单因素实验研究了工艺参数对微胶囊外观形貌、 粒径大小及分布、 包封率、 载药量和缓释性能的影响. 结果表明, 乳化剂种类和剪切时间可以显著影响微胶囊的外观形貌; 随着乳化剂用量增大, 微胶囊粒径减小, 分布变窄, 当Tween-80用量从4%增加至8%时, 微胶囊平均粒径从59.9 μm减少到29.8 μm, 跨距也从1.21减少到0.72. 随着芯壁比(质量比)减小, 微胶囊粒径和包封率均逐渐增大, 载药量逐渐减小, 当芯壁比为1:1.75时, 包封率可以达到70%以上. 微胶囊释放动力学模型符合Ritger-Peppas模型(lgQ=lgk+nlgt); 平均粒径相近而载药量不同时, 初期载药量最小的样品释放速率慢, 累积释放率低; 载药量相近而平均粒径不同时, 粒径大的样品释放速率低, 累积释放率也低. 相似文献
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Non‐Aqueous Sol–Gel Synthesis of Ultra Small Persistent Luminescence Nanoparticles for Near‐Infrared In Vivo Imaging
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Dr. Thomas Maldiney Nicole Lièvre Dr. Guillaume Yangshu Wang Prof. Laurence Motte Dr. Cyrille Richard Dr. Yoann Lalatonne 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(20):7350-7354
Ultra‐small ZnGa2O4:Cr3+ nanoparticles (6 nm) that exhibit near‐infrared (NIR) persistent luminescence properties are synthesized by using a non‐aqueous sol–gel method assisted by microwave irradiation. The nanoparticles are pegylated, leading to highly stable dispersions under physiological conditions. Preliminary in vivo studies show the high potential for these ultra‐small ZnGa2O4:Cr3+ nanoparticles to be used as in vivo optical nanotools as they emit without the need for in situ excitation and, thus, avoid the autofluorescence of tissues. 相似文献