不同反应时间和浓度对氢氧化钇/氧化钇粉末结构的影响

采用不同水热反应时间、浓度研究扇形氢氧化钇/氧化钇粉末的结构变化,并用差热分析(TG)、X射线衍射(XRD)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)对其晶型结构和形貌进行了表征。结果表明不同的反应时间分别得到立方体、棒状、扇形氢氧化钇粉末,经800℃焙烧2h后氢氧化钇前躯体完全转变成氧化钇,但形貌上没有发生显著变化。结合反应浓度推测了扇形氢氧化钇/氧化钇样品的自组装过程。     

超细氧化钇合成与表征

以硝酸钇为原料,氨水、碳酸铵、酒石酸铵为沉淀剂,聚乙二醇、十二烷基苯磺酸钠、十六烷基三甲基溴化铵为表面活性剂,在水溶液中制备氧化钇前驱体,在空气中焙烧制备氧化钇粉体;用X射线衍射(XRD)、扫描电镜(SEM)、红外光谱(IR)对样品进行表征,用激光粒度仪分析样品的晶粒团聚度.结果表明,使用氨水、碳酸铵、酒酸铵为沉淀剂所得前驱体在673 K焙烧2 h,均获得立方晶相氧化钇粉体,一级晶粒直径分别为13,40,63 nm;用小分子有机醇回流处理氧化钇前驱体(氢氧化钇),团聚体粒径为58.8 nm,焙烧后的氧化钇团聚体粒径为423 nm,说明有机醇回流处理阻止了粒子团聚.     

含脲柠檬酸钇燃烧法制备纳米氧化钇粉

以柠檬酸钇为先驱体化合物，并将脲加到柠檬酸钇中，得到一种新的含脲柠檬酸钇先驱体。两种先驱体分别经500，600，700℃和800℃煅烧，可得到纳米氧化钇粉。通过TEM和XRD研究，结果表明；Y2O3的大小是由 煅烧温度决定，随着温度升高颗粒变大；此外，在相同温度下，含脲柠檬酸钇比柠檬酸钇得到的纳米氧化钇更细。     

纳米氧化钇的制备及形貌调控研究进展

由于不同形貌结构的纳米氧化钇对其性能有重要影响,因此,探究不同制备条件下如何调控纳米氧化钇形貌结构显得尤为重要。阐述近年来纳米氧化钇的主要制备方法,包括水热-溶剂热法、共沉淀法、电沉积法等。着重从形成原理、形成条件控制及形成机理等方面分析氧化钇制备过程与其尺寸控制关系,并在此基础上对纳米氧化钇形貌调控进行阐述。     

超细氧化钇粉体的制备

湿化学法制备超细粉体时，反应、分离、干燥以及灼烧都不同程度地影响粉体的粒径及团聚。在传统的草酸沉淀法制备氧化钇基础上对溶液的浓度、pH值以及表面活性剂的选择和用量、颗粒的表面电位进行了考察研究，确定了反应过程中影响粉体粒径的各个因素，得到一次粒径50－100nm，平均粒径0.521μm，晶型良好且具有单分散趋势的超细氧化钇。     

反应条件及陈化过程对氢氧化铬氧化速率的影响

氢氧化铬是含铬二次资源中铬的重要存在形式,也是含六价铬污染物还原时的主要产物,其氧化过程的研究对铬资源的提取和铬污染的控制具有重要意义。以亚硫酸钠还原重铬酸钠制备的氢氧化铬为研究对象,实验考察了氧化温度（室温~200 ℃）、氧化时间（0~168 h）、添加剂种类（碳酸钠、硫酸钠）等因素对氢氧化铬氧化的影响,并进行了氧化方程选取和动力学拟合计算。结果表明,温度越高两种氢氧化铬样品氧化反应越充分、氧化限度越大。在无添加剂条件下,200 ℃时新制、陈化氢氧化铬的氧化速率K值分别是80 ℃时的617、4 375倍;添加剂的加入会促进其氧化反应,140 ℃条件下,新制氢氧化铬添加碳酸钠、硫酸钠为n（Na）∶n（Cr）=0.2时的氧化速率K值分别是无添加时的10、4倍;新制氢氧化铬较陈化氢氧化铬更易氧化,氧化速率K值为陈化氢氧化铬样品的1.4~1.9倍,可能与其所含结合水较多有关。     

不同形貌氢氧化镧纳米晶的光催化性能

以La(NO3)3·6H2O为镧源,采用微波水热法制备了不同形貌(例如：不规则粒状、片状、棒状)La(OH)3纳米晶。采用X射线衍射、场发射扫描电子显微镜、紫外–可见光谱等技术对所制得的产物的物相组成、形貌和光学性能进行分析。结果表明：随着前驱体浓度的增大,La(OH)3纳米晶由不规则粒状向片状转变,再由片状向棒状转变。紫外–可见光谱分析和光催化结果表明,La(OH)3纳米晶在200～400 nm具有优异的吸收能力。La(OH)3纳米棒对紫外区域吸收率最大,不规则形状的La(OH)3对紫外区域吸收率最小。La(OH)3纳米棒优于其他形貌对亚甲基蓝的光催化降解,降解率可达到93%,而纳米片和不规则粒状的光催化降解率分别为87%和75%。     

电子陶瓷用超细粉体的生产方法及评价

综述了电子陶瓷用超细粉体的生产方法及对其特征的评价；对生产过程中颗粒团聚现象进行了理论探讨并介绍了表面活性剂在减少颗粒团聚技术中的应用。     

三种表面活性剂对Fe3O4纳米颗粒的形貌影响

选用十六烷基三甲基溴化铵(CTAB)、聚乙烯吡咯烷酮(PVP)、十二烷基磺酸钠(SDS)3种表面活性剂,研究了这3类不同表面活性剂和不同添加量对Fe3O4纳米颗粒的形貌调控作用,利用透射电镜(TEM)对样品进行表征分析,并给出了机理解释。结果表明:1)3种不同的表面活性剂的加入都获得球形或近球形的纳米颗粒。根据TEM及沉积时间的综合分析,3种活性剂的平均粒径比较:SDS相似文献   

钇铝石榴石粉体制备技术的研究进展

本文对钇铝石榴石粉体制备技术的研究现状做了系统的概述,着重介绍了目前在YAG粉体的制备中应用较多的固相法、溶胶-凝胶法、溶剂（水）热法和共沉淀法等几种方法．简要地分析了这几种方法在YAG粉体制备中的优缺点,指出了共沉淀法是现阶段最具潜力的一种合成方法。     

Effect of reaction conditions on size and morphology of SiO2 powder in a sol-gel process

We have investigated effects of the reaction conditions such as mixing of solution, reactant concentration, feeding time and molecular weight of alcohol solvents on the size and morphology of silicon oxide in a sol-gel process in Rushton type reactor. To describe the intensity of mixing of solution the power input, which means the energy dissipated in the solution, was used. The particle nucleation and growth processes of silicon oxide were varied with all the reaction conditions. However, the particle morphology of silicon oxide depended mostly on the reactant concentration and molecular weight of alcohol solvents under various reaction conditions. If the supersaturation level of silicon oxide in the solution was promoted by variation of reaction conditions, the particle nucleation and growth processes were facilitaled and it resulted in reduction of relative induction time and in increase of mean particle size of silicon oxide. To explain the principal mechanism of particle growth process of silicon oxide the two-step growth model was applied.     

Effect of polymerization conditions on polyacetylene morphology

In an effort to optimize the synthesis of polyacetylene we have studied the evolution of its morphology by scanning electron microscopy (SEM) and also determined the density of the polymer. Both results are correlated and discussed.     

制备条件对氢氧化镁和碱式氯化镁组成和形貌的影响

以六水氯化镁和氨水为原料,水热法合成出了氢氧化镁和碱式氯化镁晶须。利用XRD、SEM、TG、FT-IR对产物的组成和形貌进行表征,同时考察了原料浓度、反应温度、反应时间及表面活性剂对产物形貌的影响。结果表明,在低氯化镁浓度和一定氨水滴加量的条件下产物为厚度20～50 nm,具有规则形状的纳米六方片层及其组合玫瑰花球结构的氢氧化镁,增大氯化镁溶液浓度同时减小氨水滴加量产物为直径0.5 μm、长度200 μm的碱式氯化镁单晶。     

氢氧根对半水硫酸钙晶体形貌的影响机理

以二水硫酸钙为原料在氢氧化钠-水体系中水热合成不同形貌的半水硫酸钙晶体,并通过XRD、XPS和电导率等手段对水热产物进行表征,研究了OH^-对水热产物晶体形貌的影响机理。结果表明,在碱性条件下可获得不同形貌的半水硫酸钙晶体,随着OH^-浓度的增大,纤维状形貌水热产物的含量减小而短柱状形貌的含量增多,且当OH^-浓度为1.0×10^-2 mol/L时水热产物以短柱状形貌为主。OH^-影响半水硫酸钙晶体形貌的原因：OH^-会消耗溶液中的Ca²⁺,从而促进二水硫酸钙的溶解,而Ca²⁺浓度的减少不利于半水硫酸钙晶体的成核生长;同时,OH^-对二水硫酸钙的促溶作用会增加溶液中SO₄^2-的浓度,从而促进半水硫酸钙晶体沿（110）和（200）晶面的生长;此外,OH^-在（002）晶面选择性吸附并与该晶面的Ca²⁺反应生成Ca（OH）⁺和Ca（OH）₂,从而阻碍半水硫酸钙晶体沿该晶面的生长。在以上3种作用下半水硫酸钙晶体形貌由纤维状向短柱状转变。本研究可为碱性条件下生产不同形貌半水硫酸钙晶体提供一定的理论依据。     

Effect of imidization conditions on the morphology of polyimide

A poly(amic acid) derived from pyromellitic dianhydride and oxydianiline was imidized under different conditions. The sample imidized in solution (PI‐1) showed the X‐ray diffraction pattern of a crystalline material, whereas that of the sample imidized in the solid state was essentially amorphous. Both samples were further characterized by ¹³C‐NMR spectroscopy, IR spectroscopy, electron paramagnetic resonance, and thermogravimetric analysis. The orders of polyimide in both the crystalline and amorphous states are discussed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1065–1070, 2004     

Synthesis and characterization of MC nylon/modified yttrium hydroxide nanocomposites

In this article, monomer casting (MC) nylon is synthesized. MC nylon could replace nonferrous metals in certain applications, including gears, wheels, and other moving parts. However, compared with metals, MC nylon products have poor strength and stiffness, and crack easily, especially at low temperatures. In addition, the dimensional stability of MC nylon is poor, especially in the large casting nylon products, causing significant internal stresses due to shrinkage. Thus, MC nylon cracks easily when cast and molded. The yttrium hydroxide particles are modified by stearic acid and dispersed in the caprolactam. The polymerization time is short due to fast anionic polymerization. Copolymerization with different ratios of yttrium hydroxide particles can be used to prepare the copolymer. The effects of different amounts of yttrium hydroxide on the performance of the monomer casting nylon are studied. The products are characterized using X‐ray diffraction, impact, and tensile testing. When the percentage of modified yttrium hydroxide is 0.3 wt %, the composite exhibits the maximum impact strength, thus the 0.3 wt % of modified yttrium hydroxide is the suitable percentage to enhance the impact strength of MC nylon. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43356.     

水滑石对轮胎胎侧橡胶复合材料微观形貌与性能的影响

将水滑石（LDHs）加入到轮胎胎侧橡胶中制得LDHs/橡胶复合材料,研究了LDHs在橡胶复合材料中的分散状态及对胎侧橡胶复合材料的硫化特性、力学性能和耐老化性能的影响。结果表明,LDHs穿插在炭黑粒子之间,形成均匀分散;LDHs可以促进硫化,缩短橡胶复合材料的硫化时间,并提高其定伸应力和撕裂强度、改善耐老化性能。当LDHs的用量为4份（质量）时,与未添加LDHs橡胶复合材料相比的抗张积老化系数提高了25.7%。     

Effect of various morphology and testing conditions on fiber infrared spectrum

A series of measurements verify that the accuracy, reproducibility, and quality of fiber infrared spectra strongly rely on fiber thickness and morphology, the aperture size and direction, and instrument parameters, despite the use of high resolution in microscopy by using the Continuμm microscope. The effect of fiber cross section and testing parameters on the characteristics of the FTIR microscope spectra is discussed systematically. Meanwhile, the reproducibility of the spectra has also been tested using the transmission and mapping methods. The experimental results show that the size selection of the aperture, fiber flattening, and proper contact between attenuated total reflection crystal and fiber are vitally important for high quality and accuracy of FTIR microscope spectra. Through reasonable parameter setting and sample preparation, in fact, the IR spectra of single fibers can be obtained quickly and reproducibly. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1003–1010, 2005