水热合成法制备杯状氧化锌微晶及其光学性质研究

以Zn(CH3COO)2·2H2O为源反应物,采用水热合成反应法成功地制备了杯状的氧化锌微晶粉体材料.X射线衍射(XRD)谱的结果表明获得了典型的六方结构晶体.扫描电子显微镜(SEM)照片观测到杯状的氧化锌微晶,并且单个微晶互相结合形成对称结构.实验发现,水热时间影响着晶体的形貌,对其结构变化机制进行了探讨.同时,通过...     

常压水热法制备纳米多界面结构氧化锌及其电磁波损耗特性

采用常压水热法制备了具有系列多界面结构的氧化锌,并对样品的晶体结构、微观形貌和电磁波损耗特性做了研究。通过扫描电子显微镜(SEM)研究了不同反应条件对氧化锌纳米结构形貌的影响,发现改变锌盐种类和氢氧化钠浓度能够得到不同形貌的氧化锌纳米多界面结构;动力学研究结果表明,不同锌盐制备氧化锌的成核速率几乎相等,晶体生长阶段的速率却存在明显的差异,由此提出基于极性晶面阴离子吸附的纳米氧化锌低维结构生长机理。电磁波损耗特性的初步研究结果表明,纳米界面结构的形貌对其电磁波损耗性能有显著影响。     

不同醇对溶剂热法制备氧化亚铜形貌的影响

以乙酸铜、三乙醇胺和醇为原料,采用溶剂热法制备出了不同形貌的微米氧化亚铜颗粒。通过SEM和XRD对所制备产物的形貌和物相进行分析表征,结果表明,在适当的反应温度下,不同醇类作还原剂均可生成球形氧化亚铜微晶,但随着醇羟基数量的增加,球形氧化亚铜微晶的反应生成温度逐渐降低。同时,对醇在形成氧化亚铜微晶的反应过程中所起的作用进行了初步探讨。     

合成氧化锌纳米粒子形貌的调控机理和方法

纳米ZnO作为一种重要的宽带隙半导体材料，具有与体材料明显不同的电、磁、光等性质，逐渐成为研究的热点并得到广泛应用。氧化锌纳米粒子的形貌对其性质和应用具有重要的影响。介绍了纳米氧化锌粒子制备过程中形貌调控的机理和主要方法，并讨论了氧化锌纳米粒子制备的发展趋势和研究方向。     

电场辅助溶液法制备氧化锌纳米棒阵列及其形貌研究

在外加电场辅助下用溶液法制备了氧化锌纳米棒阵列,反应过程低温、快速,且在无种子层条件下单步完成.用XRD和SEM表征了不同条件下制备的样品的结构和形貌,制备得到的氧化锌纳米棒尺寸均匀、生长致密,直径在50～200nm之间,长度1.5μm左右.分别研究了添加剂六亚甲基四胺(HMTA)和引入的辅助电场的作用及其对样品形貌的影响.研究了不同反应物浓度和反应时间下的样品形貌,讨论了纳米棒一星状双层氧化锌纳米结构在溶液中的形成和生长机理.     

炭基氧化锌复合材料的研究进展

概述了炭基氧化锌复合材料的制备方法、类型以及影响氧化锌表面形貌的主要因素。从复合材料光催化协同作用机制入手,介绍了国内外炭基氧化锌复合材料制备的研究现状,并在此基础上展望了炭基复合材料的发展方向和研究前景,希望可以对氧化锌炭基复合材料的制备提供一些有价值的参考。     

炭化温度对中间相炭微球结构的影响

以煤沥青为原料,采用热聚合的方法,在不同的温度下制备出中间相炭微球(MCMB).通过SEM、激光粒径分析和XRD等分析手段对MCMB的表面形貌、粒径分布和微晶结构进行了分析.结果表明,随着温度的升高,MCMB的粒径变大,不同温度下制备的MCMB是由具有类似石墨结构的微晶组成的.420与450℃形成的MCMB微晶层间距d002较小,430与440℃形成的MCMB微晶层间距d002较大,随着温度的升高微晶宽度La变大.     

氧化锌/石墨烯纳米复合材料制备技术的研究进展

氧化锌/石墨烯纳米复合材料在储能、光电材料与器件、光催化剂等方面具有广阔的应用前景,其所含元素无毒无害,储量丰富,适用于溶剂热法、超声空化法、电化学沉积等低成本非真空制备方法,故氧化锌/石墨烯复合材料近来成为复合材料领域研究热点之一。综述了氧化锌/石墨烯复合材料的多种制备方法,讨论了各制备方法的工艺特点与不足,分析了不同制备方法对氧化锌/石墨烯纳米复合材料形貌与性能的影响,展望了其未来工业化规模制备的发展趋势。     

不同形貌氧化锌的乙醇胺辅助水热制备及光催化性能

采用乙醇胺辅助水热的方法制备了一系列不同形貌的具有高效光催化性能的氧化锌纳米/微米晶。通过简单地调控乙醇胺的加入量得到了六方棱柱状孪晶、六方棒和三维花状等形貌。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见(UV-Vis)分光光谱等对样品进行了表征。在模拟太阳光氙灯的照射下,研究了不同形貌氧化锌光降解甲基橙的性能,发现六方棱柱状孪晶氧化锌表现出最佳的光催化活性。     

不同形貌纳米ZnO的合成及其光催化性能研究

以Zn(NO3)2·6H2O和NH4HCO3为原料,采用直接沉淀法制备了不同形貌和微观结构的纳米氧化锌。详细研究了反应终点pH值及沉淀前驱物的后处理方式等对粉体的晶体结构、形貌、粒径分布和团聚状况的影响。通过调节反应条件可分别获得网络状或颗粒状纳米氧化锌;光催化降解实验结果表明,网络状纳米氧化锌的光催化性能优于纳米颗粒状产物,而且该网络状和颗粒状纳米氧化锌的光催化活性均明显优于商品光催化剂P25。     

Tetrapod-shaped ZnO microtubes synthesized from Zn/C mixtures

We report for the first time the growth of tetrapod-shaped ZnO microtubes synthesized via a simple method. The tetrapod-shaped ZnO microtubes were synthesized from mixtures of high-purity Zn powder and activated carbon in a crucible at 930-940 °C in air without the presence of any catalyst. The ZnO microtubes were found to be grown on the arrays of ZnO microcrystals, which were horizontally grown from the inner walls of crucibles. Optical and scanning electron microscopy were utilized to observe the morphologies of the tetrapod-shaped ZnO microtubes, and X-ray diffraction was employed to study the crystal structure. The microtubes were found to be hexagonally shaped with well-defined side faces. A growth model was proposed to explain the formation of the tubular ZnO microcrystals.     

Growth and Photoluminescence Properties of Tetrapod-Shaped ZnO Microcrystals-Whiskers and Microrods

Tetrapod-shaped ZnO microcrystals in forms of whiskers and microrods have been grown in the same crucible by thermal evaporation of Zn/C mixtures at a temperature of 930℃ in air without using any catalyst. The tetrapod-shaped ZnO microrods were capped by hexagonal pyramids. It is for the first time observed that the tetrapod-shaped ZnO whiskers and microrods have quite different morphologies, and this is believed to be a result of different growth behaviors associated with these two forms of ZnO microcrysta...     

Synthesis of cup-like ZnO microcrystals via a CTAB-assisted hydrothermal route

Cup-like ZnO microcrystals were successfully synthesized by using a CTAB-assisted hydrothermal route. Zn(CH₃COO)₂·2H₂O was used as the only precursor to generate cup-like ZnO microcrystals. The morphologies and structures of the samples were characterized by XRD and SEM. The XRD pattern shows that the cup-like ZnO microcrystals are hexagonal. The SEM investigation reveals that the as-prepared ZnO product has cup-like morphology. CTAB was found to play a crucial role in determining the cup-like morphologies. A possible formation process of the cup-like ZnO microcrystals was proposed. Optical property of the product was also investigated by fluorophotometer at room temperature.     

Microwave synthesis of ZnO microcrystals with novel asymmetric morphology

This paper reports a discovery of novel morphological features of ZnO asymmetric micron-sized single crystals synthesized by microwave irradiation of W/O emulsions containing a Zn source in the inner aqueous phase. The influence of the zinc ion concentration on the size and shape is studied in detail. The morphological and structural properties show that the obtained ZnO powders are almost mono-dispersed ZnO single crystals with a novel morphology of truncated hexagonal pyramids ca. 1 μm in diameter. A scanning precession electron diffraction analysis reveals that the asymmetrically shaped ZnO single crystals thus obtained have a crystallographic c-axis perpendicular to the bottom hexagonal flat surfaces, and annular bright-field imaging indicates that the bottom surfaces are Zn-terminated ZnO(0001)-Zn polar faces. These new findings are led from a combination of well-controllable liquid-phase emulsion synthesis of the oxide powders and highly advanced atomic-resolution TEM imaging technique, suggesting for the first time a highly probable relationship between the polarity of the wurtzite-type crystal structure and the novel asymmetric morphology of the ZnO microcrystals obtained in this study.     

微米棒构筑的多脚状ZnO水热合成及生长机理探讨

以Zn(CH3COO)2和NH3·H2O生成的Zn(NH3)2 4 为前驱体,采用水热法制备了多脚状ZnO微晶,用XRD、SEM、TEM及UV-Vis进行了鉴定和表征,并对其生长机理进行了初步探讨.结果表明,多脚状ZnO微晶由微米棒构筑,属六方晶系,在短紫外光区具有较强的光吸收性能.     

Effect of Oxygen Admittance Temperature on the Growth of ZnO Microcrystals by Thermal Evaporation Technique

Hexagonally well-faceted microcrystals of ZnO have been grown by thermal evaporation of Zn powder in oxygen ambient at 700 C under atmospheric pressure. It has been observed that the properties (size and quality) of ZnO microcrystals have a strong dependence on the reactor temperature at which the oxygen gas is admitted into the growth zone. The microcrystals grown with oxygen admittance at 450 C have a length of 1 μm and a diameter of 0.75 μm while that grown with oxygen admittance at 600 C have a length of 1.5-2 μm and a diameter of 1 μm. Room temperature photoluminescence spectra show a ultraviolet (UV) emission peak at 385 nm with a green band emission at around 500 nm. The UV-to-green band emission ratio for the microcrystals grown with oxygen admittance at 450 C is observed to be 1.25 and the ratio decreases to 0.45 for the sample grown with oxygen admittance at 600 C.     

低温水浴法制备不同花状结构ZnO粉体及其发光性能研究

以二水合乙酸锌和尿素为原料,聚乙二醇-2000为改性剂,用氨水调节体系pH,采用水浴法在一定的工艺条件下制备了不同花状结构ZnO粉体。结果表明,添加聚乙二醇-2000时所制得的ZnO粉体呈现花状的结构,ZnO前驱体溶液中不同氨水量使得组成花状结构的ZnO微棒结构从六棱棒状结构向纺锤状结构转变。X射线衍射结果表明不同棒状结构组成的花状ZnO其峰(002)与峰(001)的相对强度比不同。透射电子显微镜表明六棱棒状结构的ZnO粉体呈现单晶结构,而纺锤状结构的ZnO粉体倾向于多晶结构。室温光致发光谱表明不同微棒组成的花状ZnO粉体均在约380nm存在近带边发射峰。     

棒状和球状氧化锌微晶的控制合成及其表征

以醋酸锌和尿素为主要原料,利用微乳-溶剂热法控制合成了棒状和球状ZnO微晶.用XRD、TEM、FTIR.和SAED等技术手段对两种形状的ZnO微晶进行了表征.结果表明:棒状ZnO微晶的平均尺寸为50nm×320nm,球状ZnO微晶的平均尺寸约为200nm.     

Spherical and rod-like zinc oxide microcrystals: morphological characterization and microstructural evolution with temperature

Spherical ZnO microcrystals obtained by spray pyrolysis and thermal decomposition methods as well as rod-like ZnO particles (prismatic and needle shaped) prepared from precipitation in aqueous solutions, have been characterized by electron microscopy, X-ray diffraction and infrared spectroscopy. Very different sizes of ZnO particles were obtained from spray pyrolysis. However, only the larger particles (0.7 m) were found to be slightly deformed by infrared spectroscopy. From thermal decomposition of zinc acetate, fine particles of average size 0.05 m, rather spherical and agglomeration free were obtained. The role of initial size and morphology in the thermal evolution is fundamental: very fine spherical particles (0.01–0.02 m), can be sintered to give particles of 0.1–0.3 m at 875 °C with unchanged morphology. When the temperature induces a change in spherical shape, the first microstructural changes appear to take place through the crystallographic c-axis. However, for rod-like particles, changes begin from the a, b axes, being faster for needle-shaped microcrystals.     

Formation of mushroom-like ZnO microcrystals through a solution calcination process

Mushroom-like ZnO microcrystals have been prepared via a solution calcination route, using Zn(NO₃)₂ as Zn source in the absence of any surfactants, templates or catalysts. This is the first example to prepare mushroom-like crystals as semiconductors, which are expected to show particular physical properties. The ZnO products were investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and photoluminescence (PL) spectrum measurements. A suitable concentration of Zn(NO₃)₂ solution was important for the growth of the mushroom-like products. The reported synthetic procedure is straightforward and inexpensive, and thus can be readily adopted to produce large quantities of mushroom-like ZnO microcrystals.