The structure of CeAlO3 by Rietveld refinement of X-ray powder diffraction data

The room temperature structure of perovskite CeAlO₃ has been reinvestigated by X-ray powder diffraction. The Rietveld refinement has confirmed the tetragonal symmetry; but revealed a super cell, a=5.32489(6) Å and c=7.58976(10) Å, with the space group I4/mcm. In CeAlO₃, the distortion from the ideal cubic perovskite is caused by the cooperative tilting of the AlO₆ octahedra around the primitive cubic [001]_p-axis.     

Bi12TiO20纳米粉体的制备及其光吸收特性研究

以钛酸四丁酯和硝酸铋为原料 ,利用化学溶液分解法制备了Bi12 TiO2 0 纳米多晶粉体 .采用XRD和TEM对其结构和形貌进行了表征 .结合热重 差热 (TG DTA)分析 ,探讨了Bi12 TiO2 0 晶相的形成机理 .通过UV Vis漫反射谱的测定 ,研究了Bi12 TiO2 0 纳米晶粉体的光吸收特性 .结果显示 ,从组成为化学计量比的前驱液中可以很容易制得纯Bi12 TiO2 0 纳米晶粉体 ,该Bi12 TiO2 0 纳米晶粉体呈现了在很宽的波长范围内 (5 6 0～ 385nm )对光的吸收的特性 .     

Cold compaction of ceramic powder: Computational analysis of the effect of pressing method and die shape

This paper deals with a computational analysis of the influence of the pressing method and part geometry on the final density distribution in the cold compaction process of ceramic alumina powders. The analysis is based on the explicit finite-element model proposed and validated in a previous study. The mechanical behavior of the processing material is described using a multisurface elastoplastic model, the modified Drucker-Prager/Cap model Published in Prikladnaya Mekhanika, Vol. 43, No. 10, pp. 129–134, October 2007.     

纳米累托石-TiO2光催化剂的制备及表征

以TiCl4和累托石为主要原料，制备出纳米累托石-TiO2粉末，并用X-衍射、透射电镜等对其进行表征．结果表明：纳米累托石-TiO2粉末平均直径为17．5nm当焙烧温度从500℃升至800℃时，累托石-TiO2粉末的比表面积从65．7m^2／g下降至3．3m^2／g，单位质量吸附剂的孔体积从0．1430cm。／u降到0．0213cm^3／g；当焙烧温度从300℃上升至500℃时，孔径变化不大，属中孔范围；当焙烧温度升至800℃时，一些孔道出现坍塌，不利于纳米累托石-TiO2粉末的光催化活性．     

改性壳聚精膜用于醇水混合液分离的研究──Ⅲ．超细粉末填充壳聚精膜

首次制备了用Ｓｉ３Ｎ４，ＳｉＯ２，ＴｉＨ４超细粉末填充的改性壳聚精膜，并将其用于乙醇／水混合液的分离中。实验表明壳聚糖膜经超细粉末填充后强度增大，溶胀度减小。用于乙醇／水混合液渗透蒸发分离时，分离因子和渗透通量都有提高，并在填充量为１６．７％附近出现极大值。随着料液中乙醇含量的增大，渗透通量减小，分离因子增大；随着料液温度的升高渗透通量显著增大，分离因子则稍有下降。并简单讨论了超细粉末在乙醇／水混合液分离中的作用。     

矿渣粉加固粉土的理论分析及路用性能研究

提出了矿渣粉加固粉土的相关理论。将矿渣粉在加固土中的作用归结为火山灰胶凝效应和微集料填充效应,而火山灰胶凝效应又可进一步归结为水化作用、激发作用和离子交换作用;认为微集料填充效应与矿渣粉细度极为相关;用框图归纳了矿渣粉加固土的两种作用效应。进行了矿渣粉、石灰粉加固土无侧限饱水抗压强度、水稳定性、冻稳定性、温度收缩和干燥收缩等路用性能试验,并进行比较。结果表明,矿渣粉加固土所测路用性能指标优于石灰粉加固土。为工程应用提供了试验依据。     

TiO2 粉末催化剂光催化降解室内 空气中有机污染物

本文制备了一系列 TiO2粉末催化剂, 用光催化法降解室内空气中各种微量有机污染物,最终降解率 接近 100%. 考察了晶型对光催化剂性能的影响, 结果表明,锐钛矿型 TiO2 的催化性能最好. 最后,分析了 TiO2 光催化反应机理.     

Photon interaction studies using 241Am γ-rays

We have carried out some photon interaction measurements using 59.54 keV γ-rays from a ²⁴¹Am source. These include γ attenuation studies as well as photoelectric absorption studies in various samples. The attenuation studies have been made using leaf and wood samples, samples like sand, sugar etc., which contain particles of varying sizes as well as pellets and aqueous solutions of rare earth compounds. In the case of the leaf and wood samples, we have used the γ-ray attenuation technique for the determination of the water content in fresh and dried samples. The variation of the attenuation coefficient with particle size has been investigated for sand and sugar samples. The attenuation studies as well as the photoelectric studies in the case of rare earth elements have been carried out on samples containing such elements whose K-absorption edge energies lie below and close to the γ-energy used. Suitable compounds of the rare earth elements have been chosen as mixture absorbers in these investigations. A narrow beam good geometry set-up was used for the attenuation measurements. A well-shielded scattering geometry was used for the photoelectric measurements. The mixture rule was invoked to extract the values of the mass attenuation coefficients for the elements from those of the corresponding compounds. The results are consistent with theoretical values derived from the XCOM package.     

沉淀法制备CeO2超微粉末

采用过氧化氢－－氨水沉淀法在较低温度下制备ＣｅＯ２超微粉末。试验表明，溶液起始浓度及焙烧温度以形成粉素晶体粒径有一定影响。焙烧温度在２２０－８５０℃，所得ＣｅＯ２微粉均为立方晶系，透射电测试表明，粒子基本呈球形，晶体平均粒径随焙烧温度升高而增大。控制适当条件，可制得粒径范围在５－１３ｎｍ，比表面积１１１．８ｍ＾２／ｇ的ＣｅＯ２超微粉末。