纳米Al粉体性能及热稳定性研究

本文采用等离子体电弧法制备了纳米Al粉末,用XRD、TEM、TG、DTA、热处理等测试技术研究了纳米Al粉末的组成结构、晶粒大小、晶粒形貌和热稳定性情况.结果表明,该粉体平均粒径是39nm,晶粒形貌为球状,热稳定性好.     

六边形多孔NiO纳米片的合成与表征

以硫酸镍和六次甲基四胺为原料,采用水热法制备出粒径约为90 nm的六边形Ni(OH)2纳米片,再将Ni(OH)2纳米片煅烧得到多孔六边形NiO纳米片.通过 X射线衍射(XRD)、透射电镜(TEM)等测试手段对所得产物物相和形貌进行了表征.结果表明,多孔六边形NiO纳米片属于六方晶系,孔径约为15 nm.研究发现,通过调节反应物的浓度即可以在无模板的情况下控制产物为多孔六边形或刺球形NiO纳米晶.根据实验结果,本文提出了不同形貌NiO的形成机理.     

螺旋波等离子体化学气相沉积法制备纳米碳化硅薄膜

采用螺旋波等离子体化学气相沉积 (HWP-CVD)技术在Si(100)和石英衬底上合成了具有纳米结构的碳化硅薄膜.通过X射线衍射(XRD)、傅立叶红外透射(FTIR)和原子力显微镜(AFM)等技术对所制备薄膜的结构、组分和形貌进行了分析,利用光致发光技术研究了样品的发光特性.分析表明,在700℃的衬底温度和1.33Pa的气压条件下所制备纳米SiC薄膜的平均颗粒度在3nm以下,红外透射谱主要表现为Si-C吸收.结果说明HWP-CVD为制备高质量纳米SiC薄膜的有效技术,所制备样品呈现出室温短波长可见发光特性,发光谱主峰位于395nm附近.     

氧化镍纳米晶体的制备及其过程分析

为了开发一种新型纳米氧化镍催化剂,能有效地应用于生物质气化过程中去除焦油,本文采用均匀沉淀法成功地制备了纳米氧化镍晶体,并利用TGA、FTIR、XRD、BET、YEM等分析手段对前驱体和产品的性能进行了表征.同时,对前驱体的分解过程进行了全面的分析.分析结果表明前驱体是水合碱式碳酸镍,其分子式为NiCO3·Ni(OH)2·nH2O,它能在360℃下完全分解转化为纳米NiO,同时煅烧条件对合成纳米NiO的晶体粒径影响很大.实验证实所得纳米NiO颗粒呈球形,分散性好,纯度较高,属立方晶系结构,平均粒径约为7.5nm,其BET表面积为187.98m2/g,这显示纳米NiO晶体具有作为高效催化材料的应用可行性.     

ZnO/NiO纳米异质结的合成及其光催化性能的研究

通过超声法成功制备出形貌均一的ZnO/NiO异质结光催化材料,并采用X射线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)以及光致发光光谱(PL)等分析测试手段对样品的形貌和结构进行了表征.结果表明,ZnO/NiO异质结是由直径约400～600 nm的ZnO纳米球镶嵌着NiO纳米颗粒组成.对比纯NiO纳米颗粒、纯ZnO纳米球和ZnO/NiO异质结对罗丹明B(RhB)的紫外光降解效率,ZnO/NiO异质结表现了最好的光催化活性,这主要是由于ZnO/NiO异质结可以有效的分离光生电子和空穴对,使得它们的复合机率降低,提高其光催化效率.     

纳米CNTs/SiO2/TiO2复合颗粒的制备及表征

以碳纳米管为核心,采用溶胶-回流法制备了纳米CNTs/SiO2/TiO2复合颗粒.用透射电子显微镜(TEM)、X射线衍射(XRD)、傅里叶红外光谱(FT-IR)和BET法对其表面形貌、结构和比表面积进行表征.结果表明,所制纳米CNTs/SiO2/TiO2复合颗粒为双层包覆型结构,SiO2为中间层,最外层是锐钛矿型的TiO2;红外光谱分析显示SiO2和TiO2之间形成了Ti-O-Si键;复合颗粒的比表面积是纯碳纳米管的2倍多.     

LiNO3熔盐辅助煅烧制备高分散纳米ZrO2粉体

以可溶性锆盐溶液反向滴定氨水溶液成功地制备了纳米ZrO2粉体,系统研究了反应物浓度与煅烧温度对产物粒径和形貌的影响;在反应过程中加入表面活性剂,并采用正丁醇共沸蒸馏干燥和LiNO3熔盐辅助煅烧等方法,以控制粒径、减少团聚.通过热重-差热分析(TG-DTA)、透射电镜(TEM)、X射线衍射(XRD)、比表面积分析(BET)等对样品进行了形貌表征、晶型及粒径分析.结果表明:上述多种方法联合使用能够有效控制粒径、减少团聚,制备出的纳米ZrO2粉体分散性优异,为立方晶相结构,粒径15 nm左右.     

粒径可控纳米白炭黑的制备

采用氨水催化正硅酸乙酯(TEOS)的水解缩聚法制备出纳米白炭黑,研究了氨浓度、反应温度对凝胶时间及纳米白炭黑粒度的影响,采用激光粒度分析仪、自动吸附仪、X射线衍射仪(XRD)、透射电子显微镜(TEM)对纳米白炭黑进行了表征.结果表明:通过控制氨浓度及制备温度,可实现对白炭黑粒径的有效控制;纳米白炭黑形貌为球形,一次粒径为20 nm左右;纳米白炭黑属于非晶结构且具备了微孔、介孔和大孔较为完整的孔体系.     

正交设计α-Fe2O3纳米颗粒的制备

依据正交设计实验方案,研究了以三价铁盐为原料、微量Fe(Ⅱ)为催化剂,沸腾回流条件下,液相制备α-Fe2O3球形纳米颗粒的实验过程,用XRD、TEM、粒度分布仪表征了样品的物相、形貌和粒径。结果表明:用正交表安排复杂实验体系的条件可以减少工作量,得出制备纯相α-Fe2O3的最佳条件;Fe(Ⅲ)浓度、Fe(OH)3凝胶形成温度和pH值三个因素影响样品粒径的程度依次减弱;在最佳配比下试验得到了颗粒形貌完整,粒径在50±10 nm的α-Fe2O3。     

碳修饰Zn_2SnO_4纳米颗粒的制备及光催化性质研究

利用葡萄糖做碳源,通过简单的水热法制备了碳修饰的Zn2SnO4纳米颗粒。利用X射线衍射(XRD)和扫描电镜(SEM)对样品的结构和形貌进行了表征。实验结果表明本方法制备的Zn2SnO4为立方尖晶石结构,形貌为纳米颗粒,分散性好,粒径在10~50 nm左右。拉曼光谱(Raman)表明制备的Zn2SnO4纳米颗粒中有无定型碳的存在。用所制备的样品对亚甲基蓝进行紫外光照射下的光降解实验,结果表明碳修饰的Zn2SnO4纳米颗粒光催化效率比不含碳的有所提高,可能原因是无定形碳材料具有良好的吸附力和导电能力。     

溶剂热合成氮化硼纳米晶过程中氮源种类的影响

以NaNH2和BC l3为原料,利用溶剂热方法合成了六方氮化硼纳米微晶,并用红外吸收光谱(FTIR)、X射线粉末衍射(XRD)方法分析了微粒的结构,利用透射电子显微镜(TEM)观测了BN微粒的粒度和微观形貌。与早期用L i3N为氮源合成的氮化硼(产物中具有较多纳米棒)相比,本文中制备的氮化硼纳米晶主要呈球形,颗粒粒度明显增大,而且产率有较大幅度的提高。     

Controlled synthesis of PAN/Ag2S composites nanofibers via electrospinning-assisted hydro(solvo)thermal method

The Ag₂S nanoparticles embedded in polyacrylonitrile (PAN) fibers matrix were successfully prepared by the combining electrospinning with the hydro(solvo)thermal process, without the presence of any templates or organic surfactants. What's more, the size and content of Ag₂S nanoparticles was tunable through proper controlling of the reaction conditions. Consequently, the Ag₂S nanoparticles with 10-100 nm diameter could be obtained via this two-step synthetic route. The as-synthesized composites nanofibers were investigated by X-ray diffraction(XRD), field-emission scanning electronic microscopy (FE-SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), Fourier transform infrared spectroscopy (FT-IR), and photoluminescence( PL), respectively. What's more, a possible formation mechanism of Ag₂S nanoparticles grown on PAN nanofibers was also proposed.     

Size-controlled synthesis of LaAlO3 by reverse micelle method: Investigation of the effect of water-to-surfactant ratio on the particle size

Lanthanum monoaluminate (LaAlO₃) nanoparticles have been synthesized using microreactors made of poly(oxyethylene) nonylphenyl ether (Igepal CO-520)/water/cyclohexane microemulsions. The control of particle size was achieved by varying the water-to-surfactant molar ratio. The synthesized and calcined powders were characterized by thermogravimetry–differential thermal analysis (TGA-DTA), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). Differential thermal analysis showed that LaAlO₃ phase transformation decreases with increase in water/surfactant (R) value. Pure LaAlO₃ phase was synthesized by annealing at 800 °C for 2 h in air directly from amorphous precursors, without formation of intermediate phase. The average particle size was found to increase with increase in water-to-surfactant ratio (R). FTIR analysis was carried to monitor the elimination of residual oil and surfactant phases from the microemulsion-derived precursor and calcined powder.     

微乳液法制备二氧化硅包覆ZnS:Mn/CdS纳米晶

采用微乳液法制备核壳结构ZnS:Mn/CdS(～4.5nm)纳米晶,为获得水溶性纳米晶,继续向此微乳液添加硅酸乙酯(TEOS),并使用氨水作为催化剂,通过TEOS水解缩聚反应,在ZnS:Mn/CdS粒子表面生长连续的二氧化硅壳层.采用透射电子显微镜(TEM)、X射线衍射(XRD)、红外光谱(IR)、光致发光谱(PL)对其表面形貌、结构和光学特性进行表征.ZnS:Mn /CdS纳米粒子表面被二氧化硅壳层完全包覆,粒径大小约为10nm左右,粒子均匀性好.由于二氧化硅相无定形且透光性良好,二氧化硅包覆ZnS:Mn/CdS纳米晶的光学特性与未包覆的ZnS:Mn/CdS极其相似.     

反相微乳液法合成超细磷酸镁铵

利用反相微乳液法制备磷酸镁铵(MAP),并使用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、红外光谱仪(FT-IR)及热分析仪(TG-DSC)对其进行表征.结果表明,反相微乳液法制备出的MAP分布更窄,尺寸更小;不同方法得到了晶型不同的MAP;其中十六烷基三甲基溴化铵作为表面活性剂制备出的MAP粒径分布最窄;采用十二烷基苯磺酸钠作为表面活性剂制备出的MAP粒径最小,热稳定性最好.     

Production and Study of Silver Nanoparticles by 532 nm Laser Pulse Ablation in NaCl Solution

In this experimental research, silver nanoparticles are produced in NaCl solution by the laser ablation method. Our aim was to investigate the effect of the amount of NaCl in the ablation medium on the characteristics of nanoparticles. A 7 ns pulsed Neodymium YAG laser (Nd:YAG) at 5 J/cm2 fluence and 532 nm wavelength was employed to produce Ag nanoparticles in distilled water with four different concentrations of NaCl. The optical properties, size distribution, and agglomeration of nanoparticles were investigated by several diagnostics. The UV–Visible absorption spectra of the Ag nanoparticles exhibit absorptions in the UV region because of surface plasmon resonance. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to study the size distribution and morphology of nanoparticles. Dynamic light scattering (DLS) was employed to measure the hydrodynamic size of nanoparticles in suspensions. With X-ray diffraction (XRD) pattern, the lattice structure of nanoparticles was studied. Fourier transform infrared (FTIR), photoluminescence (PL) spectra were obtained to observe the molecular structure and atomic energy levels of particles.     

自蔓延燃烧法制备ZrO2纳米粉体

以氧氯化锆为原料,采用一种低温而且快速的溶胶凝胶自蔓延燃烧法制备了纳米ZrO2粉体颗粒,通过X射线衍射仪(XRD)和透射电镜(TEM)分析探讨了柠檬酸与金属离子的物质的量比和杂质离子NH;和Cl-的存在对ZrO2粉体颗粒的形成和粉末晶粒尺寸大小的影响.本次试验成功的制备了粒径为30～90 nm的近球形ZrO2纳米颗粒,试验结果表明,NH4+和Cl-两种离子的存在阻碍了ZrO2粉体长大形成更大的颗粒,柠檬酸与金属离子的物质的量比例越大,燃烧产生的瞬间高温越容易使ZrO2粉体颗粒长大.     

A novel sonochemical synthesis and nanostructured assembly of polyvinylpyrrolidone-capped CdS colloidal nanoparticles

Nanoparticles of cadmium sulfide (nano-CdS) have been successfully prepared from an aqueous solution of cadmium chloride and sodium sulfide by a novel sonochemical method. Through adding polyvinylpyrrolidone K30 (PVP) as the dispersant, a yellow translucent colloidal solution of cadmium sulfide which was considerably stable within at least one month was obtained. The characterizations of nanoparticles by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM) and FT-IR spectroscopy showed good properties of small size, high surface area and crystal structure. The size of the prepared nanoparticles was about 3–5 nm according to XRD spectra and TEM images. Poly(diallyldimethylammonium chloride) (PDDA) has been employed to fabricate multilayer films on quartz wafer and indium tin oxide (ITO) electrode in a layer-by-layer manner. Atomic force microscopy (AFM) displayed the dense coverage of the substrate surface by the nanoparticles. UV–vis absorption spectroscopy confirmed the consecutive growth of PDDA/nanoparticles layer pairs. The photoelectrochemical and the electrochemical behaviors of the prepared CdS particle were examined as well.     

离子交换树脂均匀沉淀法制备MgO纳米粒子

以(Mg(NO3)2·6H2O, (NH4)2CO3 和NH3·H2O为原料,采用两种离子交换树脂均匀沉淀法分别制备MgO纳米粒子.用热分析、X射线粉末衍射(XRD)、透射电子显微镜(TEM)、高分辨电子显微镜(HR TEM)、选区电子衍射(SAED)和BET等对所制备的MgO粒子进行了表征.结果表明:经700 ℃焙烧后制备的MgO纳米晶体属六方晶系,样品分散性较好,平均粒径约为25 nm;MgO纳米晶体清晰、有序的电子衍射点阵,表明晶体的结晶度较好;纳米粒子a和b的比表面积分别为31 m2/g and 32 m2/g.