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991.
992.
本文以柠檬酸为络合剂,采用微波辅助溶胶凝胶法制备了微米粒径的Gd_(0.4)(MoO_4)_3:1.6Eu~(3+)红色荧光粉;采用X射线粉末衍射仪、扫描电子显微镜和荧光光谱仪等对样品进行了分析和表征,讨论了荧光粉的合成方法对其表面形貌和发光性能的影响。最终将该样品与InGaN芯片结合制成发光二极管。实验结果表明:采用该法合成的具有类白钨矿结构的Gd_(0.4)(MoO_4)_3:1.6Eu~(3+)红色荧光粉为1~2μm的类球状小颗粒,且颗粒均匀,具有较窄的粒度分布,有利于LED芯片涂覆。荧光光谱显示该产品在395 nm具有强吸收峰,可与近紫外InGaN芯片相匹配,是一种可用于近紫外芯片激发的白光LED红色荧光粉。与InGaN芯片结合制成的发光二极管在617 nm处发射出可被肉眼观测的强红光。 相似文献
993.
木质素系和萘系分散剂在煤水界面的吸附性能 总被引:7,自引:0,他引:7
研究了两种木质素类分散剂SL(木质素磺酸钠)和MSSL(改性磺化碱木质素钠盐)和一种萘系分散剂(FDN)在大同煤表面的吸附量和动力学, 结果表明, SL和MSSL在煤表面的吸附量远比FDN的大, 但是拟合所得的Langmuir平衡常数K和吸附速率常数ka都比FDN的小, 这表明SL和MSSL在煤表面的吸附能力比FDN略差, 吸附速率较慢. 采用IR和XPS研究了煤表面分散剂吸附层的结果表明, 吸附了SL和MSSL的煤表面具有明显的“红移”现象, 并且SL和MSSL在煤表面的吸附层厚度分别为7.22和4.61 nm, 而FDN的吸附层厚度较小, 为2.11 nm. 分析认为, SL和MSSL在煤表面的吸附以氢键力为主, 吸附量较大, 吸附层较厚, 在煤表面呈多点式吸附; FDN主要以π电子极化吸附在煤表面呈卧式吸附, 吸附强度较大, 吸附层较薄. 相似文献
994.
采用固相法制备了用于白光LED的Eu3+和碱土离子(Li+,Na+,K+)共激活的钼酸盐荧光粉AMoO4(A=Ca,Sr).通过X射线衍射图片看出,Eu3+和Na+的掺入降低了晶格参数,同时衍射峰强度明显增加.本文研究了荧光粉的激发光谱和发射光谱.它的激发谱覆盖了从240nm到500nm的范围,在470nm处有一个激发峰,这说明它能够被GaN LED发出的蓝光有效激发.发射谱表明它能够发射峰值位于616nm和624nm的红光.实验研究了碱土离子的量(摩尔分数)对AMoO4:Eu3+发光性能的影响,0.25是最合适的掺杂量.反应时间和反应温度对发光性能也有很大的影响.搅拌均匀的反应物在800℃灼烧3h得到的样品发光强度最强. 相似文献
995.
DAI Mengjiao MA Weiguang HAN Fangjie HAN Dongfang HAN Lipeng WANG Wei ZHAO Bolin HAN Dongxue NIU Li WANG Zhenxin 《高等学校化学研究》2021,37(3):763-771
The photoelectrochemical properties of semiconductors mainly depend on the size and shape of the corresponding nanoparticles. Herein, 3D WO3 nanosheets were controllably synthesized with the aid of polyethyleneimine, which presents enhanced photocurrent responses. Based on this excellent photoelectrochemical property, a photoelectrochemical chip was prepared by lithography technology for the smart monitoring of the antioxidant capacity(AC) in red wine and exhibits a series of advantages inclu-ding rapid response time, high sensitivity, and long-lasting stability. The mechanism of the present photoelectrochemical sensing was explored and shows a single electron transfer reaction. Furthermore, only 200 μL of samples are required for one testing, which demonstrates that the present photoelectrochemical chip can be potentially integrated with a portable commercial device(such as a mobile phone) for further research and development of food and drug supervision. 相似文献
996.
《Helvetica chimica acta》2017,100(4)
Heavy metal complexes exhibit high phosphorescent efficiency and have been used extensively for electrophosphorescent emitters in the past 16 years. In 2006, we initially reported the use of the popular ligand, 8‐hydroxyquinoline (Q) to coordinate with the heavy metal ions and obtained the red‐infrared phosphorescent emission. In this paper, 8‐hydroxyquinoline has been modified at the 5‐position by electron‐donating and attracting groups and platinum complexes based on 2‐phenylpyridine and 8‐hydroxyquinoline derivatives were synthesized. The electron‐withdrawing group CF 3 and NO 2 lowers the HOMO level of the Q ligand and results in a N^O centered enhanced red‐infrared phosphorescence emission. The complex with CF 3 modification exhibits the highest phosphorescence quantum yield in solid state with a life time of 1.17 μs. 相似文献
997.
在600℃温度下,采用液相燃烧法合成了Sr2+、Eu2+和Mn2+三掺的BaMgAl10O17(BAM)蓝绿荧光粉。用XRD、SEM和荧光光谱仪分别分析和表征该荧光粉的物相、形貌和光致发光性能。结果表明,液相燃烧法合成BAM的温度明显低于传统的高温固相合成法;合成的纳米棒均匀、无团聚现象;荧光光谱仪分析表明Eu2+、Mn2+离子间存在能量传递,且Sr2+能有效提高BAM的发光强度,约为固相法制备荧光强度的1.8倍。BAM:0.1Eu2+,0.04Mn2+,0.05Sr2+色坐标为(0.146,0.250),属于蓝绿光。 相似文献
998.
A novel red emitting phosphor, Eu3+-doped Ca2SnO4, was prepared by the solid-state reaction. X-ray powder diffraction (XRD) analysis confirmed the formation of Ca2SnO4: Eu3+. Field-emission scanning electron-microscopy (FE-SEM) observation indicated a narrow size-distribution of about 500 nm for the particles with spherical shape. Photoluminescence measurements indicated that the phosphor exhibits bright red emission at about 615 nm under UV excitation. The excellent luminescence properties make it possible as a good candidate for plasma display panels (PDP) application. Splitting of the 5D0-7FJ transitions of Ca2SnO4: Eu3+ suggests that the Eu3+ ions occupied two nonequivalent sites in the crystallite. The luminescence lifetime measurement showed a bi-exponential decay, providing other evidence for the existence of two different environments for Eu3+ ions. 相似文献
999.
T. H. Chang 《中国化学会会志》2016,63(2):233-238
Eux(NH4)2‐2xTi3O7 nanoporous phosphor was prepared by ion exchange method. (NH4)2Ti3O7 nanotubes were employed as the host structure by treating H2Ti3O7 with NH4OH solution and the activator, Eu2+, was introduced into the host via ion exchange. This is an easy and feasible way to prepare a phosphor. The synthesized samples were characterized using TEM, XRD, N2 adsorption‐desorption isotherm, TPR, and fluorescence spectrophotometer. Experimental results showed that a portion of Eu2+ ions was oxidized into Eu3+ ions during ion exchange, resulting in the present phosphor with blue‐emitting and red‐emitting. Moreover, the tubular structure of Eux(NH4)2‐2xTi3O7 was distorted as Eu2+ was placed into the host structure. This distortion is attributed to the electrostatic interaction between Eu2+ and the electric field of the host structure. 相似文献
1000.
A comprehensive study of acridine spectra with variation of pH, wave length of excitation, deuteration of the solvent, etc.,
has been made. The excited state protonation of acridine is found extra-ordinarily excitation wavelength sensitive near the
red edge of the first absorption band. The proton association takes place very fast (K
PT ~ 1010 sec-1) on excitation at the red edge of the first absorption band (ree) and acridinium emission is observed while it is slow on
short wavelength excitation (swe). The reaction rate slows down at lower temperature which is indicated by a delay in the
initiation of the effect by ~ 8 nm on ree. The acridinium type emission with ree at 80 K shows that proton tunnelling is the
chief mechanism of proton transfer. The quantum yields are also found wavelength dependent. Contrary to previous observations
acridinium ion also shows a ree shift at 80 K. 相似文献