一维纳米材料的ECR-CVD方法制备

应用电子回旋共振微波等离子体化学气相沉积方法(ECR-CVD)进行了一维纳米材料的制备.以Fe3O4纳米粒子为催化剂,采用不同的气源,在多孔硅基底上制备出了碳纳米管、掺硼碳纳米管以及异质结构的纳米管.利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和 X射线光电子谱(XPS)对样品的形貌、结构及组分进行表征.     

纳米材料产业化发展中的若干问题

纳米是一种长度单位,1 nm等于10-9m.按照实空间三维坐标体系,任何一种材料只要其中有一维的尺寸是纳米级的(1～100 nm之间),即可称为纳米材料;而按照材料的外形又可划分为零维(颗粒)、一维(晶须、纤维、管)、二维(膜或薄膜)、三维(块体)纳米材料,其中三维(块体)纳米材料是一个例外,因为尽管其外形尺寸不是纳米级的,但其中包含了纳米材料物种.按照纳米材料的组成则可以将其划分成无机、有机、高分子(聚合物)、金属、陶瓷、生物以及复合纳米材料等.纳米材料是无法直接目测的,必须使用电子显微镜(透射电子显微镜、扫描电子显微镜、原子力显微镜等)或超高倍光学显微镜将其放大数千倍以上才可以观测、确认.     

Fe_3O_4纳米材料的制备及其抗革兰氏菌研究

以FeCl2·4H2O和水合肼为原料,在聚乙二醇200中进行反应制备出Fe3O4纳米材料。用X射线衍射(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)和超导量子干涉仪(SQUID)对产品的结构、形貌和磁学性质进行了表征。并研究了Fe3O4纳米材料对革兰氏阴性菌和革兰氏阳性菌(大肠杆菌和地衣芽孢杆菌)的抑制作用。结果表明Fe3O4纳米材料对革兰氏菌具有抑制作用,且对革兰氏阳性菌的抑制作用优于革兰氏阴性菌。     

一维GaN纳米材料制备及其光电器件研究进展

一维GaN纳米材料相对于薄膜材料在光电器件应用方面具有诸多优势,本文主要论述一维GaN纳米材料的主要制备方法及其光电器件应用的研究进展。首先分别介绍采用MOCVD、MBE、CVD及模板法制备一维GaN纳米材料,重点论述GaN纳米材料的结构与形貌调控。其次介绍一维GaN纳米材料分别应用于主要光电器件包括LED、太阳能电池、激光器及光探测器的研究动态,讨论纳米材料性能、结构以及制备技术对其器件性能的影响。最后对一维GaN纳米材料的发展与应用前景进行展望。     

一维纳米材料的研究进展

一维纳米材料因其优异的光学、电学及力学性能等特性而引起了凝聚物理界、化学界和材料界科学家们的关注,近年来成为纳米材料研究的热点.综述了一维纳米材料的种类,常用制备方法;介绍了一维纳米材料制备的最新进展,以及一维纳米材料的应用.     

直接氧化法制备准一维氧化物纳米材料的研究进展

准一维氧化物纳米材料因其独特的光学性能、电学性能及几何结构而成为当前纳米材料研究领域的热点和重点.论述了直接氧化法制备准一维氧化物纳米材料原理,着重介绍了这一方法在准一维氧化物纳米材料制备中的应用,并对其前景作了简要的展望.     

一维ZnO纳米材料的溶液法合成及光催化性能的研究现状

溶液法合成一维ZnO纳米材料是目前最常用、最经济的方法。综述了溶液法合成一维ZnO纳米材料的流程、原理以及制备工艺对一维ZnO形貌和结构的影响,并对其光催化性能的研究现状及发展趋势进行了总结和展望,为开展溶液法合成一维ZnO纳米材料及性能研究提供一定的指导。     

锂镍钒氧纳米材料的制备及其电化学性能研究

以国产V2O5粉末、H2O2、无水LiAc和Ni(Ac)2·4H2O为原料,采用溶胶-凝胶法和水热法制备了锂镍钒氧纳米材料。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、傅里叶红外光谱(FT-IR)和电化学测试方法对材料进行了研究。结果表明:该方法所制备的锂镍钒氧纳米材料呈现均一的纳米颗粒形状,并且具有良好的电化学性能。     

SiC一维、准一维纳米材料的制备工艺研究

综述了近年来SiC一维、准一维纳米材料制备工艺的最新研究进展,重点介绍了模板生长法、化学气相沉积法、熔体生长法、碳热还原法和溶胶-凝胶法的工艺特点,并对不同工艺方法制备的SiC一维、准一维纳米材料的微观形貌、优异性能进行了简要概述,总结了现阶段SiC一维、准一维纳米材料制备工艺研究所面临的问题及发展前景.     

填充叠氮化铜的碳纳米管纳米材料的制备研究?

首先采用电化学沉积法在碳纳米管中沉积铜,再利用叠氮化反应制备填充叠氮化铜的碳纳米管纳米材料。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨透射电镜(HRTEM)和X射线能谱(EDS)对样品的微观形貌和晶体结构进行表征。结果表明,利用电化学沉积方法在定向碳纳米管中空管腔内合成了针状纳米枝晶铜,非连续的枝晶结构有利于后续的气固叠氮化反应,最终制备得到填充叠氮化铜晶体的碳纳米管纳米材料。     

Shape-controlled synthesis of PbCrO4 micro/nanostructures and their luminescent properties

PbCrO4 with different morphologies have been synthesized via a facile sonochemical route from an aqueous solution of lead acetate and potassium dichromate in the presence of nitrilotriacetate acid (H3NTA). The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The pH and the concentration of complexing reagent were found to have close relation with morphology of the final product. The possible growth mechanism of PbCrO4 microcube has been proposed. UV-Vis spectra and room-temperature photoluminescence of the PbCrO4 micro/nanostructures have also been investigated. Results showed that all the samples possessed strong photoluminescence (PL) properties, suggesting that the micro/nanostructures could be used in novel optoelectronic devices.     

Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of synchrotron X-ray spectromicroscopy and related methods. 1. Artificially aged model samples

On several paintings by artists of the end of the 19th century and the beginning of the 20th Century a darkening of the original yellow areas, painted with the chrome yellow pigment (PbCrO(4), PbCrO(4)·xPbSO(4), or PbCrO(4)·xPbO) is observed. The most famous of these are the various Sunflowers paintings Vincent van Gogh made during his career. In the first part of this work, we attempt to elucidate the degradation process of chrome yellow by studying artificially aged model samples. In view of the very thin (1-3 μm) alteration layers that are formed, high lateral resolution spectroscopic methods such as microscopic X-ray absorption near edge (μ-XANES), X-ray fluorescence spectrometry (μ-XRF), and electron energy loss spectrometry (EELS) were employed. Some of these use synchrotron radiation (SR). Additionally, microscopic SR X-ray diffraction (SR μ-XRD), μ-Raman, and mid-FTIR spectroscopy were employed to completely characterize the samples. The formation of Cr(III) compounds at the surface of the chrome yellow paint layers is particularly observed in one aged model sample taken from a historic paint tube (ca. 1914). About two-thirds of the chromium that is present at the surface has reduced from the hexavalent to the trivalent state. The EELS and μ-XANES spectra are consistent with the presence of Cr(2)O(3)·2H(2)O (viridian). Moreover, as demonstrated by μ-XANES, the presence of another Cr(III) compound, such as either Cr(2)(SO(4))(3)·H(2)O or (CH(3)CO(2))(7)Cr(3)(OH)(2) [chromium(III) acetate hydroxide], is likely.     

Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of synchrotron X-ray spectromicroscopy and related methods. 2. Original paint layer samples

The darkening of the original yellow areas painted with the chrome yellow pigment (PbCrO(4), PbCrO(4)·xPbSO(4), or PbCrO(4)·xPbO) is a phenomenon widely observed on several paintings by Vincent van Gogh, such as the famous different versions of Sunflowers. During our previous investigations on artificially aged model samples of lead chromate, we established for the first time that darkening of chrome yellow is caused by reduction of PbCrO(4) to Cr(2)O(3)·2H(2)O (viridian green), likely accompanied by the presence of another Cr(III) compound, such as either Cr(2)(SO(4))(3)·H(2)O or (CH(3)CO(2))(7)Cr(3)(OH)(2) [chromium(III) acetate hydroxide]. In the second part of this work, in order to demonstrate that this reduction phenomenon effectively takes place in real paintings, we study original paint samples from two paintings of V. van Gogh. As with the model samples, in view of the thin superficial alteration layers that are present, high lateral resolution spectroscopic methods that make use of synchrotron radiation (SR), such as microscopic X-ray absorption near edge (μ-XANES) and X-ray fluorescence spectrometry (μ-XRF) were employed. Additionally, μ-Raman and mid-FTIR analyses were carried out to completely characterize the samples. On both paint microsamples, the local presence of reduced Cr was demonstrated by means of μ-XANES point measurements. The presence of Cr(III) was revealed in specific areas, in some cases correlated to the presence of Ba(sulfate) and/or to that of aluminum silicate compounds.     

多孔壳/磁核结构光催化剂的制备及表征

以聚氧乙烯-聚氧丙烯-聚氧乙烯三嵌段共聚物(P123)为结构导向剂,钛酸丁酯(TBOT)为钛源,SiO2/NiFe2O4为核,制备了具有多孔结构可磁分离的Ti O2/SiO2/NiFe2O4光催化剂。采用N2吸附-脱附、TEM、HRTEM、SEM、XRD和VSM等手段对样品进行分析表征。样品颗粒呈球形,分布均匀,平均粒径约为40nm,具备良好的磁分离性能。以硝基苯为模拟物测定其光催化活性,UV光照条件下,240min内硝基苯污染物降解完全,表明该光催化剂具有良好的光催化活性。     

草酸根离子诱导PbWO4有序纳米结构的合成和生长机理

采用直接沉淀法制备PbWO_4有序纳米结构,以草酸根双羧基阴离子为其生长阶段结构导向剂。使用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、红外光谱(IR)和透射电子显微镜(TEM)等手段对其表征,研究了草酸根离子在PbWO_4纳米晶生长阶段的控制作用,并提出了PbWO_4有序纳米结构的形成机理.     

The microstructure and electrochemical characteristics of LiFePO4/carbon-network composite

LiFePO4/carbon-network composite was synthesized by a high temperature solid-state method using the natural sawdust as carbon precursor. The microstructure of the as-synthesized sample was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), respectively. The results revealed that the LiFePO4 particles with diameters ranging from 30 to 150 nm were well connected by carbon networks. The electrochemical performance of the composite was characterized using galvanostatic charge-discharge technique. The initial discharge capacity of LiFePO4/carbon-network cathode reached 126 mAh x g(-1) with 0.2 C rate.     

磷酸铁包覆纳米锰酸锂的改性研究

以水热法合成的纳米MnO2为模板,合成了以棒状结构为组成单元的球状LiMn2O4纳米材料,并首次用FePO4对其进行了表面包覆改性。通过XRD、SEM、TEM、EDS等表征手段对材料的结构、形貌及组成元素进行了分析,并测试了材料的电化学性能。结果表明,经过1%(质量分数)FePO4包覆的LiMn2O4材料的电化学性能得到明显改善,在1C下首次放电比容量达128.6mAh/g,循环100次后仍保持97.3mAh/g,容量保持率为75.7%;在0.1C下充电,在0.1C、0.2C、0.5C、1C、2C、3C、4C下连续放电,放电比容量分别可达131.2mAh/g、128.0mAh/g、127.1mAh/g、126.0mAh/g、117.8mAh/g、110.9mAh/g和104.6mAh/g。     

高分散度Fe3O4纳米球的粒径控制合成及磁性能

采用CTAB作保护荆,在较低温度下,成功地制备出高分散度的Fe3O4纳米材料.通过改变反应条件和保护刺的种类,可在20～360nm范围内有效调控Fe3O4纳米颗粒的粒径.利用X射线衍射仪、透射电子显微镜和扫描电子显微镜等对样品的晶体结构、粒径、形貌和化学组成进行了分析.结果表明:所得Fe3O4纳米晶的粒径均匀,形貌为球形,分散度好.利用振动样品磁强计测量了室温下140nm粒径样品的磁性能.结果表明,Fe3O4纳米材料具有典型的软磁特性.     

纳米颗粒磁增强SBA-15介孔复合材料的制备及磁性能

利用浸渍法合成了Co₃O₄/SBA-15和CoFe₂O₄/SBA-15介孔纳米磁性材料, 并利用X射线粉末衍射(XRD)、 透射电子显微镜(TEM)、 场发射扫描电子显微镜(FESEM)及振动样品磁强计(VSM)对样品的微观结构和磁性能进行了分析。结果显示, Co₃O₄及CoFe₂O₄纳米颗粒分布在SBA-15介孔材料的孔道中, 可有效提高SBA-15介孔材料的磁性能。研究发现, SBA-15介孔纳米磁性材料的磁特性由掺杂的纳米磁性颗粒的性质决定, 其磁性能随Co₃O₄及CoFe₂O₄含量的增加而升高, 矫顽力可达400Oe, 饱和磁化强度达9emu/g。