水热/溶剂热法形貌控制合成铜基微纳米晶体颗粒材料的研究进展

简述了利用水热/溶剂热法合成铜基微纳米晶体颗粒材料的最新研究进展。介绍了氧化亚铜、碱式碳酸铜、碱式钼酸铜、碱式氯化铜、碱式磷酸铜等铜基微纳米材料的合成方法。对铜基微纳米晶体颗粒材料生长机理和形貌控制合成进行了分析,获得了对铜基微纳米晶体颗粒材料生长规律的一般性认识,实现了在水热/溶剂热条件下对铜基微纳米晶体颗粒材料生长的形貌控制合成。     

北大：新型纳米稀土化合物的控制合成和性质研究取得进展

北京大学化学与分子工程学院严纯华课题组日前在新型纳米稀土化合物的控制合成和性质研究中取得较大进展。他们首次以具有较低分解温度的稀土配合物为前躯体（如稀土苯乙酰丙酮和稀土三氟乙酸配合物等），在高沸点混合溶剂（油酸、油胺和十八烯）中通过调节前躯体的热分解方式和溶剂组成控制晶体的成核和生长过程，一步获得了高度晶化、尺寸均一可调、形貌可控、无团聚、易分散于非极性溶剂的、具有新颖结构的全系列单一或复合稀土氧化物和氟化物纳米材料。通过分散溶剂的调节和材料表面控制，上述纳米晶可白发组装成高度有序的超晶格结构。同时，相关化合物呈现出显著的纳米材料的结构和表面效应，产生了与相应的体相材料不同的光学性质。这一新型合成路线可推广用于复合稀土化合物、其它主族和过渡族化合物纳米材料的控制合成。     

自组装技术在特殊形貌无机纳米材料制备中的作用

目前无机纳米材料的研究主要集中于低维无机纳米材料的制备,如纳米颗粒、纳米纤维等,其制备方法已相当成熟,而对高维特殊形貌无机纳米材料的研究相对较少。近年来,具有特殊形貌的高维无机纳米材料因独特的结构和表面性质在催化、太阳能电池、传感器、微波吸收、医学等领域展现出优于低维纳米材料的性能,但制备出的材料种类少,形貌不均一,可控性较差。因此,研究者们致力于特殊形貌无机纳米材料生长机理的研究,为材料制备提供有效的理论依据。制备无机纳米材料的方法有微乳液法、溶胶-凝胶法、电化学法、水/溶剂热法等。其中水/溶剂热法制备的无机纳米材料具有晶粒发育完整、粒度分布均匀、颗粒之间少团聚、原料价格较便宜的优点,因此被广泛应用于特殊形貌无机纳米材料的制备。自组装技术作为超分子领域的新概念,在制备特殊形貌的材料中发挥着重要作用,其主要作用是将低维的纳米结构单元通过氢键、范德华力、静电力等非共价键作用力进行连接而组装成各种复杂的层级结构。现已通过自组装技术合成了片状、棒状、花状、海绵状、树枝状等特殊形貌无机纳米材料。其中片状材料的生长过程如下:第一步是纳米颗粒的奥斯特瓦尔德熟化过程,第二步是熟化的纳米颗粒定向附着自组装成片状材料。棒状材料的生长过程出现了两种情况,第一种与片状形成过程相同,第二种则是先形成片状,然后片状发生卷曲形成棒状材料,棒状材料再定向附着自组装成长径比不同的棒状材料。花状、海绵状、树枝状等复杂形貌的形成则是基于片状或棒状材料,通过氢键自组装而成。自组装过程会受到表面活性剂或模板剂、溶剂、沉淀剂、酸碱度等因素的影响。研究者们发现利用水热法制备纳米材料时,引入合适的表面活性剂或模板剂,能够促使低维纳米结构单元进行有序自组装而形成结晶度好、尺寸均匀的特殊形貌纳米材料。通过改变表面活性剂或模板剂、溶剂、沉淀剂的种类和剂量及酸碱度等因素,影响纳米颗粒的生长方向、生长速率及颗粒之间的作用力,进而控制产品的形貌和尺寸。本文对近年来国内外利用自组装技术制备特殊形貌无机纳米材料的研究成果进行了介绍,分析讨论了自组装过程的影响因素,并对自组装制备特殊形貌无机纳米材料的发展方向和应用前景进行了展望,以期为制备性能优越的特殊形貌纳米材料提供参考。     

溶剂热/水热法控制合成一维无机纳米材料的影响因素探讨

纳米材料的物相、尺寸和颗粒形状等决定其性能和应用，其可控制备至关重要。主要讨论了在溶剂热/水热法制备一维无机纳米材料过程中，溶剂、浓度、反应温度、反应时间、表面活性剂等因素对产物的物相、尺寸和形貌等的影响。     

碲化铋纳米花的微反应合成

以Te粉和Bi_2O_3为原料,三正丁基膦（TBP）与油酸为溶剂,在微反应系统中合成了碲化铋纳米花,采用X射线衍射、透射电子显微镜、扫描电子显微镜对合成产物的物相和微观形貌进行了分析,考察了反应温度、反应前躯体溶液浓度以及反应时间对合成产物形貌的影响,研究结果表明,随着反应温度的提高,纳米颗粒生长速度加快,而前躯体溶液浓度的增加导致纳米片的团聚加剧,反应温度提高,纳米片的尺寸增大。     

浮动催化法制备碳管若干影响因素的研究

采用浮动催化法,利用卧式单一高温电阻炉,在以无水乙醇为碳源的反应体系中通过改变催化剂、反应气氛及流量、添加剂等实验参数合成了形貌不一的碳微纳米材料;采用SEM和Raman对产物进行了形貌观察和表征;比较了这些实验参数对浮动催化法制备碳纳米管的影响,并对其作用机理进行了简单分析.     

Cu2ZnSnSe4纳米晶的溶剂热合成研究

利用溶剂热法在不同的反应条件下合成了CZTSe纳米材料，研究了反应温度、反应时间以及不同溶剂对样品的结构与形貌的影响，用X射线衍射仪（XRD）、场发射扫描电镜（FESEM）对所合成的样品进行了表征。结果表明反应温度的升高和反应时间的延长有助于提高CZTSe结晶性能。在240℃时CZTSe样品呈现非常尖锐的特征衍射峰，为约50nm的纳米颗粒。反应溶剂会影响样品的结晶性能及形貌。油胺作为反应溶剂时样品的结晶性能最佳，不同溶剂条件下样品的形貌不同。     

贵金属纳米材料形貌控制合成的研究进展

调控粒子的形貌和尺寸是改变贵金属纳米颗粒催化性能的一种重要方式,简要评述了贵金属纳米材料的几种形貌控制合成方法以及常见贵金属催化剂形貌控制合成的研究进展,并对贵金属纳米材料形貌控制工作在光催化研究领域的应用提出了设想。     

磁性纳米材料的控制合成及介观特性研究进展

由于纳米材料具有不同于宏观块材的特性,诸如量子尺寸效应、小尺寸效应等,越来越多的科学家致力于纳米材料的合成和介观特性的研究,推广其在现实生产生活中的应用。磁性纳米材料,如铁、钴、镍等,具有独特的磁学和催化等介观特性,近年来得到了广泛关注。发展高度可控且温和、简便的合成方法,构筑具有优异特性的新型纳米结构,实现对目标材料物理、化学性质的剪裁,已经发展成为无机纳米材料合成的重要发展方向。目前,磁性纳米材料的合成方法取得了广泛的研究,可以有效实现磁性纳米材料的可控合成及组装。通过对材料的微结构调控可以有效控制材料的尺寸、形貌、成分及表界面性质,从而实现对磁性纳米材料的磁学、催化等介观性质的优化。     

水热法制备微纳米荧光材料

无机材料的颗粒尺寸和微观形貌与它们的化学组成以及结构一样对其物理化学性质有重要的影响。在众多的材料合成方法中,水热合成因为在控制产物尺寸和形貌方面具有显著的优势逐渐得到了材料研究学者的广泛关注。荧光材料对分散性及均匀性有很高的要求,而各种类型的有机添加剂辅助的水热反应可以提高产物的均匀性、分散性,实现形貌的多样性。综述了水热合成制备微纳米结构荧光材料的现状,重点介绍了表面活性剂、生物大分子、有机酸、有机溶剂类等有机添加剂对水热合成过程的辅助作用并简单阐述了影响机理。最后,总结了目前在水热合成微纳米荧光材料领域存在的问题,并展望了其发展前景。     

纳米Co_2O_3前躯体的室温固相反应工艺研究

采用室温固相反应合成纳米Co3O4前驱体,用X-射线衍射分析(XRD)和透射电镜(TEM)等手段对前驱体的制备工艺进行了研究,就不同工艺对前驱体形貌、尺寸和产率的影响规律进行了探讨。结果表明,采用CoSO4·7H2O和H2C2O4·2H2O为原料制备的前驱体均为单斜相的CoC2O4·2H2O。在压应力作用下,前驱体的形貌主要为不规则多边形,颗粒尺寸在50～500nm范围内变化。而无压应力作用时,前驱体形貌为不规则形状,颗粒尺寸均匀,约为150～200nm。前驱体的产率与工艺参数有较大关系,对反应物分别研磨或反应物混合研磨、施加压力、升高温度和提高H2C2O4·2H2O的量将有利于提高前驱体的产率。     

Block copolymers as templates for functional materials

There are applications and devices which require controlled distribution of material functionality (electrical, optical, catalytic, magnetic) in two or three dimensions. At the nanometer length scale, attempts to meet this challenge have included template-mediated materials chemistry [1] in which track-etched membranes, porous alumina and zeolites serve as the nanoscale reaction vessels for the synthesis of the functional materials. The ability to control both the length scale and the spatial organization of block copolymer morphologies makes these materials particularly attractive candidates for use as templates in the synthesis of functional nanocomposites. Appropriate choices of the repeat units of the block sequences renders them capable of selectivity sequestering preformed inorganic nanoclusters or selectively solubilizing inorganic reagents for in-situ cluster synthesis. Methods exist to produce nanoscale voids which percolate through the structure, leading to processes which coat or backfill the channels with functional materials.     

Solvothermal synthesis and characterization of functionalized graphene sheets (FGSs)/magnetite hybrids

Novel functionalized graphene sheets (FGSs)/Fe₃O₄ hybrids were synthesized through a facile one-step solvothermal method using FeCl₃ as iron source, ethylene glycol as the reducing agent and graphene nanosheets as templates. The morphology, composition and phase structure of as-prepared hybrid materials were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). These results showed that denseness, size and crystallinity of magnetite can be altered by controlling the reaction parameters. Magnetization measurement indicated that both coercivity and saturation magnetization increased linearly with increasing magnetite concentration in hybrid materials. The measured relative complex permittivity indicated that a high resistivity existed in the FGSs/Fe₃O₄ inorganic hybrids. The magnetic loss was caused mainly by ferromagnetic natural resonance, which is in agreement with the Kittel equation. The novel inorganic hybrid materials are believed to have potential applications in the microwave absorbing performances.     

膜控晶体生长及纳米微粒的形成

膜控晶体生长不同于一般在溶液中的沉淀与结晶，由膜形成的有机界面具有空间定位和空间约束、定域化学控制及成核过程和晶体生长的立体化学专一的特性，使得晶体的结构、形状和尺寸上得到控制，并具有良好的重现性，由此可获得具有光、电以及磁特性的纳米功能材料。研究膜控晶体生长不仅可以模拟生物体系内的生物矿化作用，而且对于材料科学也有着特别重要的意义和应用前景。     

Preparation of AgO<Subscript>2</Subscript>/GrO nanocomposites by hydrothermal method and investigation of photoluminescence properties

This paper reports a novel processing route for producing AgO₂/GrO nanocomposites by hydrothermal method. AgO₂/GrO nanocomposites as semiconductor materials have been synthesized via a facile one-step process using AgNO₃ and glucose as starting reagents. We investigated the influence of the thermal decomposition temperature and reaction time, on the morphology and the particle size of AgO₂/GrO nanocomposites. The AgO₂/GrO nanocomposites were characterized by FT-IR, UV–Vis spectra, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. The obtained results exhibited that the synthesized nano product by calcining for 4 h showed excellent uniformity and quality.     

Influence of sintering temperature on photoluminescence of Gd2O3:Eu3+ phosphors prepared by liquid phase reaction method

Nanostructured materials with diameters less than 100 nm have been studied vigorously in recent years. Many studies have been devoted on exceptional optical properties induced by quantum confinement for fundamental research and applications. For excellent luminescence characteristics, phosphor particles have to acquire fine size, narrow size distribution, non-aggregation, good crystalline, and spherical morphology. A liquid-phase reaction method was chosen in this study due to the low reaction temperature. Gd2O3:Eu3+ phosphors were synthesized by the liquid-phase reaction method and the effect of activation temperature on optical properties of the phosphors was investigated.     

Mechanochemical synthesis of nanoparticles

The results of recent investigation of the mechanochemical synthesis of inorganic nanoparticles are reviewed. It was demonstrated that, by selecting suitable chemical reaction paths, stoichiometry of starting materials and milling conditions, mechanochemical processing can be used to synthesise a wide range of nanocrystalline particles dispersed within a soluble salt matrix. Selective removal of the matrix phase by washing the resulting powder with appropriate solvents can yield nanoparticles of the desired phase. This technique has been shown to have advantages over other methods of producing nanoparticles in terms of low cost, small particle sizes, low agglomeration, narrow size distributions and uniformity of crystal structure and morphology.     

Dynamic mechanical property and photochemical stability of perlite/PVA and OMMT/PVA nanocomposites

This work focused on the preparation of poly (vinyl alcohol) (PVA)/inorganic composites. Perlite and organically modified montmorillonite (OMMT) were used as the inorganic compounds. (PVA)/inorganic nanocomposite films were prepared by solvent solution method. The morphology, dynamic mechanical property, and the photochemical stability of these films were studied. The reaction pathway between these OMMT and PVA was suggested that the hydrogen bonding and hydrophobic interactions contributed to the preparation. The obtained new materials have different thermal, mechanical, and photochemical stability from other single components.     

Packing-density calculation of thin fluoride films from infrared transmission spectra

Optical thin films of MgF(2) and NdF(3) have been made by molecular-beam deposition in ultrahigh vacuum. The film packing density was calculated from the water amount that filled the cavities of the films in air. For that the transmission in the IR spectral region with a characteristic water absorption band at a wave number of 3400 cm(-1) was measured. The influence on the packing density of a modification of thin-film morphology by stratification of very thin sublayers of different crystallizing fluorides is tested.     

微波合成固体氧化物燃料电池阴极材料La1-xSrxMnO3

采用微波无机合成技术制备固体氧化物燃料电池(SOFC)阴极材料La1-xSrxMnO3,表征了结构和性能,研究了微波功率、反应时间和原料粒度等微波合成条件对其性能的影响,以及合成La1-xSrxMnO3的反应机理.