Solvothermal synthesis of the complex fluorides KMgF3 and KZnF3 with the Perovskite structures

The complex fluorides KMgF3 and KZnF3 with Perovskite structures were solvothermally synthesised at 150-180degreesC and characterised by means of X-ray powder diffraction, scanning electron microscopy, thermogravimetric analysis and infrared spectroscopy.

Solvothermal synthesis of complex fluorides KCoF3 and KNiF3

Complex fluorides KCoF3 and KNiF3 with perovskite structures were solvothermally synthesized at 120-180 C and characterized by means of X-ray powder diffraction, scanning electron microscopy. thermogravimetric analysis and infrared spectroscopy.

Synthesis of zeolite NaA membranes with high permeance under microwave radiation on mesoporous-layer-modified macroporous substrates for gas separation

This article reported the NaA zeolite membranes with high permeance synthesized with microwave heating method under different conditions: (1) on a macroporous substrate in gel, (11) on a mesoporous/macroporous (top-mesoporous-layer-modified macroporous) substrate in gel, and (111) on a mesoporous/macroporous substrate in sol. In general, the H-2 permeance of the NaA membranes by microwave heating in gel was usually at the level of 10(-6) mol s(-1) m(-2) Pa-1, much higher than that by the conventional hydrothermal synthesis. At similar H-2/C3H8 permselectivity. On the substrate modified mesoporous top layer, the H-2 permeance of the NaA membranes by microwave heating in gel or sol was further enhanced, while maintaining comparable H-2/C3H8 permselectivity, due to the prevention of penetration of the reagent into the pores of the macroporous substrate. Meanwhile, the synthesis took less time in sol than in gel on the mesoporous/macroporous substrate. The NaA membranes synthesized in sol had larger permeance than those in gel and underwent transformation in shorter time. The permeation of C3H8 suggested that there existed unwanted intercrystalline pores or defects in the membranes. © 2005 Elsevier B.V. All rights reserved.

Synthesis and Characterization of One-Dimensional and Molecular M(tren)InAsS4 (M = Mn, Co, and Zn) Compounds with a Noncondensed AsS33- Unit

Four transition-metal-amine complexes incorporating indium thioarsenates with the general formula M(tren)InAsS4 (M=Mn, Co, and Zn) and a noncondensed AsS33- unit have been prepared and characterized. Single-crystal X-ray diffraction analyses show that compound 1 (M=Mn) crystallizes in the triclinic crystal system (space group: P (1) over bar) and consists of a one-dimensional (1D) inorganic (1)(infinity){[InAsS4](2-)} chain and [Mn(tren)](2+) groups bonded to the opposite sides of an eight-membered In2As2S4 ring along the backbone of the infinite inorganic chains. Compounds 2 (M=Mn), 3 (M=Zn), and 4 (M=Co) are isomorphous molecular compounds. They all crystallize in the monoclinic crystal system (space group: P2(1)/c). The Mn2+ cation of [Mn(tren)](2+) in 1 has a distorted octahedral environment, while the transition-metal cations of [M(tren)](2+) in the other three compounds locate in trigonal-bipyramidal environments.

微/纳米结构氟化物溶剂热合成及其光学性质研究

本文主要利用Liquid-Solid-Solution（LSS）方法合成了一系列的碱土金属氟化物纳米粒子, 具有微米结构的Ba2ClF3体系以及复合金属氟化物NaMgF3纳米晶。利用X－射线衍射（XRD）、透射电镜（TEM）、扫描电镜（FE-SEM）、红外光谱（IR）等技术对合成材料的结构、形貌、组成等进行表征，采用紫外-可见吸收光谱、荧光光谱（PL）、荧光寿命等手段评价合成材料的光致发光性能；探讨了油酸作为表面活性剂在纳米晶形成过程中的作用，并阐述了纳米晶的生长过程及可能的生长机理。对氟化物的胶体溶液的发光性质作了研究，并提出了可能的发光机理。 采用LSS方法制备的一系列碱土金属氟化物（CaF2，SrF2，BaF2）纳米晶结晶完好，具有碱土金属氟化物体材料的立方相结构。制备所得的碱土金属氟化物纳米晶分别具有被截的八面体，立方体和立方片形貌，粒子尺寸较均匀，分布范围较窄。制备的纳米晶由于表面被油酸的长烷基链所包覆，可以溶于非极性溶剂如环己烷形成稳定透明的胶体溶液。三种纳米晶的环己烷胶体溶液在光致发光光谱中在400nm左右出现了一个较强的发射峰。这可能是由在纳米晶的形成过程中产生的缺陷和电子中心所造成的。 采用LSS方法在较低的温度下（160oC）成功地制备了一维Ba2ClF3六方微米棒。制备的Ba2ClF3微米晶结晶完好，具有其相应体材料的斜方六面体结构。由于斜方六面体相晶胞表现出六方相的特性，因此具有各向异性。在包覆剂油酸的作用下，生成一维的六方微米棒。制备的六方微米棒具有较好的分散性，光滑的棒表面以及清晰的棱。同时，油酸的加入，氢氧化钠量，反应物加入量以及反应时间均对形貌和尺寸有所影响。通过调节合成参数，我们成功了具有不同尺寸和长宽比的微米棒。 采用LSS方法制备了复合氟化物NaMgF3纳米晶。制备的NaMgF3纳米晶结晶完好，具有正交晶相的结构。粒子平均尺寸约为38.6 nm。所得的纳米晶可溶于环己烷溶剂形成稳定透明的胶体溶液，其胶体溶液在400 nm左右有一个强的发射峰。

Microwave-assisted hydrothermal synthesis of hydroxy-sodalite zeolite membrane

A high quality pure hydroxy-sodalite zeolite membrane was successfully synthesized on an alpha-Al2O3 support by a novel microwave-assisted hydrothermal synthesis (MARS) method. Influence of synthesis conditions, such as synthesis time, synthesis procedure, etc., on the formation of hydroxy-sodalite zeolite membrane by MAHS method was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and gas permeation measurements. The synthesis of hydroxy-sodalite zeolite membrane by MAHS method only needed 45 min and synthesis was more than 8 times faster than by the conventional hydrothermal synthesis (CHS) method. A pure hydroxy-sodalite zeolite membrane was easily synthesized by MAHS method, while a zeolite membrane, which consisted of NaX zeolite, NaA zeolite and hydroxy-sodalite zeolite, was usually synthesized by CHS method. The effect of preparation procedures had a dramatic impact on the formation of hydroxy-sodalite zeolite membrane and a single-stage synthesis procedure produced a pure hydroxy-sodalite zeolite membrane. The pure hydroxy-sodalite zeolite membrane synthesized by MARS method was found to be well inter-grown and the thickness of the membrane was 6-7 mum. Gas permeation results showed that the hydrogen/n-butane permselectivity of the hydroxy-sodalite zeolite membrane was larger than 1000. (C) 2004 Elsevier Inc. All rights reserved.

Synthesis of carbon nanotube bundles with mesoporous structure by a self-assembly solvothermal route

A kind of carbon nanotube bundle has been synthesized by a simple one-step solvothermal reaction between Na and hexachlorobenzene (HCB) using NiCl2 as catalyst precursor. Before the reaction, NiCl2 was initially dispersed ultrasonically in cyclohexane then prereduced by Na at 230degreesC to produce small Ni particles in reduced state. The tubes thus-produced have a uniform outer diameter of about 20 nm, an inner diameter of 4 nm, and are highly ordered assembled as bundles which have a 2D hexagonal arrangement as proven by SAXS and TEM experiments.

Size-controlled synthesis and characterization of quantum-size SnO2 nanocrystallites by a solvothermal route

By using ethylenediamine as both an alkali and ligand, quantum size SnO2, nanocrystallites were synthesized with a solvothermal route. The transmission electron micrographs (TEM) were employed to characterize the morphologies of the products. The crystal sizes of the as-synthesized SnO2 were ranged form 2.5 to 3.6 nm. The crystal structure and optical properties of the products were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, optical absorption spectra, photoluminescence and Raman spectra.