Synthesis and photoluminescent properties of water-soluble TbF_3 nanoparticles

Monodispersed and water-soluble TbF3 nanoparticles were synthesized at a relatively low temperature in aqueous solution using citric acid as an additive,and characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FE-SEM),Fourier transform infrared spectra(FTIR),photoluminescence(PL) spectra and lifetime.The as-prepared TbF3 nanoparticles had orthorhombic structure and were composed of monodispersed spherical particles with an average particle size of 50 nm.The excitation spectrum...     

铝硅酸盐中间体对TiO2纳米粒子团聚及相转变的抑制

以粉煤灰为原料,通过与NaOH煅烧、水解合成铝硅酸盐中间体(ASI),向sol-gel法制备的TiO2溶胶中加入ASI,经处理得到钛铝硅酸盐复合材料(TiO2/ASI).X射线衍射分析(XRD)和紫外-可见漫反射光谱(DRS)研究ASI对sol-gel方法制备TiO2纳米晶形成过程和相转变的影响.研究结果表明铝硅酸盐中间体不但能抑制TiO2纳米粒子的团聚,而且能够有效地抑制TiO2由锐钛矿型向金红石型的相转变,由此所制备TiO2与ASI的钛铝硅酸盐复合材料(TiO2/ASI)对溶液中亚甲基蓝的吸附性能高于单一的TiO2或铝硅酸盐中间体.     

Photoluminescence properties of LaF3：Eu^3＋ nanoparticles prepared by refluxing method

The europium-doped LaF3 nanoparticles were prepared by refluxing method in glycerol/water mixture and characterized with X-ray diffraction(XRD), field emission scanning electron microscopy(FE-SEM), UV-vis diffuse reflectance spectrum, and photoluminescence spectra. The results of XRD indicated that the obtained LaF3: Eu3+ nanoparticles were well crystallized with a hexagonal structure. The FE-SEM image illustrated that the LaF3: Eu3+ nanoparticles were spherical with an average size around 30 nm. Under irradiation of UV light, the emission spectrum of LaF3: Eu3+ nanoparticles exhibited the characteristic line emissions arising from the 5D0→7FJ (J=1, 2, 3, 4) transitions of the Eu3+ ions, with the dominating emission centered at 590 nm. In addition, the emissions from the 5D1 level could be clearly observed due to the low phonon energies (-350 cm-1) of LaF3 matrix. The optimum doping concentration for LaF3: Eu3+ nanoparticles was determined to be 20mol.%.     

铝硅酸盐中间体对TiO2纳米粒子团聚及相转变的抑制

以粉煤灰为原料, 通过与NaOH煅烧、水解合成铝硅酸盐中间体(ASI), 向sol-gel法制备的TiO₂溶胶中加入ASI, 经处理得到钛铝硅酸盐复合材料(TiO₂/ASI). X射线衍射分析(XRD)和紫外-可见漫反射光谱(DRS)研究ASI对sol-gel方法制备TiO₂纳米晶形成过程和相转变的影响. 研究结果表明: 铝硅酸盐中间体不但能抑制TiO₂纳米粒子的团聚, 而且能够有效地抑制TiO₂由锐钛矿型向金红石型的相转变, 由此所制备TiO₂与ASI的钛铝硅酸盐复合材料(TiO₂/ASI)对溶液中亚甲基蓝的吸附性能高于单一的TiO₂或铝硅酸盐中间体.     

Eu3+掺杂新颖铝硅酸盐的合成、表征及发光特性

在温和的固相反应条件下，通过水解反应制备了与NaGdSiO4同构的Eu^3＋掺杂的新颖铝硅酸盐晶体发光材料NaAlSiO4：Eu^3＋，样品用X射线衍射分析和场发射电子扫描显微镜表征，实验结果表明，Eu^3＋掺杂铝硅酸盐在紫外光的激发下能够发射出较强的红色荧光，文章也讨论了不同烧结温度和不同掺杂浓度对材料发光的影响．     

铝硅酸盐中间体的活性评价

采用粉煤灰与 Na OH煅烧、水解合成铝硅酸盐活性中间体对有机染料进行脱色研究。样品用 FTIR和 XRD表征 ,活性实验采用 UV- Vis光谱分析方法 ,实验结果表明 ,活性中间体对有机亚甲基蓝碱性染料在短时间内有较好脱色效果。     

巧用PTC元件

为了介绍方便先对PTC元件的特性给以说明。PTC元件是在钛酸钡(BaT_1O_3)的固溶体中掺合微量稀土元素,用制造陶瓷工艺制成的半导体电阻元件,它具有正温度系数,即Positive、Temperature Coffi-cent。简称PTC,这种元件的电阻—温度特性曲线如图1.在温度较低时,即小于居里点温度范围内,具有很小的负温度系数,大于居里点温度时,这种元件具有很大