Synthesis of neodymium hydroxide nanotubes and nanorods by soft chemical process

A facile soft chemical approach using cetyltrimethylammoniurn bromide (CTAB) as template is successfully designed for synthesis of neodymium hydroxide nanotubes. These nanotubes have an average outer diameter around 20 nm, inner diameter around 2 nm, and length ranging from 100 to 120 nm, high BET surface area of 495.71 m(2) g(-1). We also find that neodymium hydroxide nanorods would be obtained when CTAB absented in reaction system. The Nd(OH)(3) nanorods might act as precursors that are converted into Nd2O3 nanorods through dehydration at 550 degrees C. The nanorods could exhibit upconversion emission characteristic under excitation of 591 nm at room temperature.

Solution-phase synthesis of Au@ZnO core-shell composites

A novel solution-phase method for the preparation of Au@ZnO core-shell composites was described. With this method, the composites were grown without heating that is usually needed in other solution methods. Atomic force microscopy (AFM) results show that the diameter of Au@ZnO core-shell composites is about 10.5 nm. X-ray photoelectron spectroscopy (XPS) was applied to characterize Au@ZnO core-shell composites. The optical properties of Au@ZnO core-shell composites, including UV-vis absorption and photo luminescence (PL), were observed at room temperature.

Multi-color long-lasting phosphorescence in Mn2+-doped ZnO-B2O3-SiO2 glass-ceramics

Multi-color LLP phenomenon was observed in Mn2+-doped ZnO-B2O3-SiO2 glassceramics after the irradiation of a UV lamp at room temperature. Transparent ZnO-B2O3-SiO2 glass emitted reddish LLP while opaque glass-ceramics prepared by the glass sample after heat treatment emitted yellowish or greenish LLP. The change of the phosphorescence is due to the alteration of co-ordination state of Mn2+. The phosphorescence of the samples was seen in the dark with naked eyes even 12 h after the irradiation with a UV lamp (lambda(max) = 254 nm) for 30 min. Based on the approximative t(-1) decay law of the phosphorescence, we suggest that the LLP is attributed to the thermally assisted electron-hole recombination.

蓝紫色ZnO-Al_2O_3-SiO_2长余辉陶瓷

通过高温固相法首次合成并报道了兰紫色ZnO Al2O3 SiO2长余辉陶瓷,系统地研究了其发光和缺陷性质。在强度0.6mW·cm-2,主峰254nm的UVP紫外灯下激发15min,然后关闭激发源,样品发射兰紫色长余辉。撤去激发源以后5s,余辉初始强度为230mcd·m-2,色坐标为(0.1292,0.0984)。暗视场中,8h以后余辉仍然肉眼可辨。样品的紫外可见发射和不同时间的余辉发射光谱显示:荧光发射位于390nm,来源于基质的自致发光;而余辉有两个发射峰,主峰位于390nm,肩峰位于520nm。这表明样品中存在两种余辉发射中心。由余辉衰减曲线可以看出,这两种余辉发光都由一个快过程和一个慢过程组成。其中,慢过程决定了材料的长余辉时间。从时间依赖的余辉强度倒数曲线可以看出,余辉强度与时间成反比,这表明余辉发光的机理为电子空穴复合过程。热释光谱显示:样品分别在92和250℃附近出现两个宽的热释峰,说明材料中至少存在两种具有不同陷阱深度的电子或空穴缺陷中心。

量子尺寸ZnO的溶胶法制备及光学性质研究现状

量子尺寸氧化锌是重要的氧化物半导体材料之一 ,文中简单介绍了它的溶胶法制备及粒子生长和聚集过程 ,着重阐述了其光学性质研究现状和光致发光机理 ,并展望了未来的发展方向。

Long lasting phosphorescence, thermoluminescence and electron spin resonance property of Mn2+ activated ZnO-Al2O3SiO2 ceramic

The long lasting phosphorescence (LLP) phenomenon in Mn2+-doped ceramic based on ZnO-Al2O3-SiO2 (ZASM) is observed. After irradiation by a UVP standard mercury lamp peaking at 254 nm with a power of 0.6 mW/cm(2) for 15 min, the ceramic sample emits a bright green light peaking at 519 nm, which can be seen in the dark even 15 h after the removal of UVP standard mercury lamp by the naked eyes whose limit of light perception is 0.32 mcd/m(2). The initial afterglow intensity reaches about 1900 mcd/m(2), and the color coordinate (X, Y) is (0.2280, 0.5767) at about 10 s after stopping irradiation. The thermoluminescence (TL) spectra show that there are at least three kinds of trap centers with different trap levels while electron spin resonance (ESR) spectra indicate that there are electron- and hole-trapping centers induced after irradiation by a UVP standard mercury lamp. Based on these measurements, the LLP is considered to be due to the recombination of electrons and holes at trapping centers with different levels, which are firstly thermally released back to Mn2+ and then give rise to the bright green LLP at room temperature.