钽催化磁控溅射法制备GaN纳米线

利用磁控溅射技术通过氮化Ga2O3/Ta薄膜,合成大量的一维单晶纤锌矿型氮化镓纳米线.用X射线衍射、扫描电子显微镜、高分辨透射电子显微镜,选区电子衍射和光致发光谱对制备的氮化镓进行了表征.结果表明;制备的GaN纳米线是六方纤锌矿结构,其直径大约20～60 nm,其最大长度可达10 μm左右.室温下光致发光谱测试发现363 nm处的较强紫外发光峰.另外,简单讨论了氮化镓纳米线的生长机制.     

氨化Ga2O3 /Nb膜制备的GaN纳米线的光学和微观结构特性的研究

采用射频磁控溅射技术在硅衬底上制备Ga2O3/Nb薄膜,然后在900℃下于流动的氨气中进行氨化制备GaN纳米线.用X射线衍射(XRD)、透射电子显微镜(TEM)和高分辨透射电子显微镜详细分析了GaN纳米线的结构和形貌.结果表明:采用此方法得到的GaN纳米线有直的形态和光滑的表面,其纳米线的直径大约50nm,纳米线的长约几个微米.室温下以325nm波长的光激发样品表面,只显示出一个位于367 nm的很强的紫外发光峰.最后,简单讨论了GaN纳米线的生长机制.     

类金刚石碳纳米线的制备及生长机理

采用热蒸发法制备了类金刚石碳纳米线,利用透射电子显微镜(TEM)和高分辨率透射电子显微镜(HRTEM)对样品的形貌和结构进行观察,发现该碳纳米线具有圆形实心结构,表面光滑,直径10～40 nm;拉曼光谱研究显示特征峰出现在1 352 cm-1和1 586 cm-1处,为典型的类金刚石结构.用CO辅助生长机理解释类金刚石碳纳米线的形成过程.     

氧化钕纳米线的制备与表征

以硝酸钕和尿素为主要原料,多孔阳极氧化铝膜(AAO)为模板,分别采用普通浸渗和压力浸渗法制备了氧化钕纳米线.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM),X射线衍射仪(XRD)和能量仪(EDS)对纳米线的形貌,结构及组成进行了表征.结果表明:两种浸渗方法均可得到氧化钕纳米线,压力溶胶浸渗有利于模板纳米孔填充度的提高,可以得到高长径比的氧化钕纳米线.     

氢氧化镧纳米线的水热合成及其表征

以硝酸镧为原料,氢氧化钾为矿化剂,采用水热法成功制备出了氢氧化镧纳米线,并利用X射线衍射(XRD),选区电子衍射(SAED),透射电子显微镜(TEM)对所形成纳米线的物相和结构进行了表征.探讨了氢氧化镧纳米线的生长机制,和温度对其形貌变化的影响规律.研究发现,由于较大的晶体结构各向异性.六方相氢氧化镧沿[100]晶向取向生长,合成出单晶的氢氧化镧纳米线;较高的反应温度有利于制备相对较长,结晶完善的氢氧化镧纳米线的合成.     

表面活性剂辅助水热法制备ZnS纳米线

用十二烷基硫醇做表面活性剂,用水热法在180℃,12 h条件下制备了ZnS纳米线.实验发现硫醇可以诱导ZnS纳米粒子沿着一维方向生长.所得产物ZnS纳米线为六方纤锌矿结构,直径为50 nm～100 nm,长度10 μm～20 μm.用X射线衍射(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、荧光发射光谱(PL)和紫外漫反射光谱(UV)等手段对所得纳米线进行了表征,并初步探讨了硫醇在限制ZnS纳米晶一维方向生长的机理.     

InN纳米线的制备与表征

采用静电纺丝法制备出了高长径比的立方相In2O3纳米线。将In2O3纳米线置于NH3气流中进行原位氮化反应,合成得到了高质量的InN纳米线,转化率高达100%。通过调节氮化反应的温度及时间,系统研究了制备InN纳米线的最佳合成工艺参数。利用这种方法得到的氮化铟纳米线具有长径比高、直径分布单一、纯度高以及产量大的特点,为今后InN纳米器件的大规模制备和应用提供了一个有效的途径。     

模板法电化学沉积超长铜纳米线制备及其性能

用恒电位电化学沉积法，尝试在氧化铝模板纳米孔内制备超长铜纳米线。透射电子显微镜（TEM）和扫描电子显微镜（SEM）分析结果表明：在较低的沉积电位下，纳米线表面较为光滑且呈现条纹结构，直径均匀，大约100nm，线长可达40-50μm，放置一段时间后离解成颗粒状；较高沉积电位下，纳米线的边缘粗糙不平，主要由晶粒连接而成，晶粒之间有空隙存在。金属纳米线的生长实际上是金属颗粒的堆积过程，金属原子之间无较强的化学键存在。由X射线衍射（XRD）、高分辨透射电子显微镜（HRTEM）分析得知，低电位下所得纳米线为单晶结构，沿[111]方向生长，而高电位下则出现了孪晶结构。     

化学沉积法制备铜纳米管与纳米线

以多孔氧化铝膜为模板,通过化学沉积法制备Cu纳米管与纳米线。分别用透射电子显微镜（TEM）、X射线衍射仪（XRD）对制备的样品进行了形貌分析与结构表征。结果表明,成功组装出Cu纳米管与纳米线。研究发现,Cu纳米管与纳米线制备成功与否取决于前处理过程中的还原步骤。Cu纳米管的外径与Cu纳米线的直径可通过改变模板制备工艺,进而改变模板孔径来调节;Cu纳米管的内径可由沉积时间的变化来控制。     

CoPt合金纳米有序阵列制备及热处理对其磁性的影响

用电化学沉积法,在阳极氧化铝模板（AAO）中成功制备了直径为φ50nm的CoPt合金纳米线的高度有序阵列。纳米线的结构和磁学特性分别用透射电子显微镜、扫描电子显微镜、X射线衍射仪和振动样品磁力计（VSM）测试。结果表明,CoPt合金纳米线是以fcc结构存在。当外加磁场与纳米线的线轴平行时,测得的矫顽力Hc为2400 Oe,剩磁比为0．75,而当外加磁场与纳米线线轴垂直时,所测得的矫顽力仅为600 Oe,剩磁比为0．25。这表明纳米线阵列具有明显的各向异性,纳米线的易轴方向为纳米线线轴方向。热处理过程中合金的微结构发生了变化,可以极大地提高材料的矫顽力。     

Catalytic Growth of Large-Scale GaN Nanowires

A novel lanthanon seed was employed as the catalyst for the growth of GaN nanowires. Large-scale GaN nanowires have been synthesized successfully through ammoniating Ga₂O₃/Tb films sputtered on Si(111) substrates. Scanning electron microscopy, x-ray diffraction, high-resolution transmission electron microscopy, and Fourier transform infrared spectroscopy were used to characterize the samples. The results demonstrate that the nanowires are single-crystal hexagonal wurtzite GaN. The growth mechanism of GaN nanowires is also discussed.     

Synthesis of one-dimensional GaN nanorods by Tb intermediate layer with different thicknesses

GaN nanorods were synthesized by magnetron sputtering and ammonification system, and the thickness of Tb intermediate layer was changed to study the effect on GaN nanorods. The resultant was tested by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra. The results show that the thickness of Tb layer has an evident effect on the modality, quality, and luminescence properties of GaN nanorods. PL spectra at room temperature show a very strong emission peak at 368 nm and a weak emission peak at 387 nm, and the intensities of the peak for the produced samples reach the maximum when Tb layer is 20 nm. Finally, the optimal thickness of 20 nm of Tb intermediate layer for synthesizing GaN nanostructures is achieved.     

Preparation of GaN Nanorods by Rare Earth Metal Tb Catalyst-Assisted Process

利用稀土金属Tb作为催化剂,通过氨化磁控溅射在Si(111)衬底上的Ga203/Tb薄膜制备出GaN纳米棒.X射线衍射和傅里叶红外吸收谱测试结果表明,制备的样品为六方结构的GaN.利用扫描电子显微镜、透射电子显微镜和高分辨透射电子显微镜对样品进行测试,结果显示样品为单晶结构的纳米棒,直径为80～200 nm,长度达几十微米.最后简单地讨论了GaN纳米棒的生长机制.     

Effect of ammoniating temperature on microstructure and optical properties of one-dimensional GaN nanowires doped with magnesium

One-dimensional GaN nanowires doped with Mg element have been successfully prepared on Si (1 1 1) substrates by magnetron sputtering through ammoniating Ga₂O₃/Mg thin films, and the effect of the ammoniating temperatures on the microstructure and optical properties of the GaN nanowires was investigated in detail. X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS), FT-IR spectrophotometer, Scanning electron microscope (SEM), high-resolution transmission electron microscope (TEM), and photoluminescence (PL) spectrum were carried out to characterize the microstructure, morphology, and optical properties of GaN nanowires. The results demonstrate that ammoniating temperature has a significant effect on microstructure, morphology and optical properties of GaN nanowires. GaN nanowires after ammoniation at 900 °C for 15 min are straight, smooth and of uniform thickness along spindle direction with the highest crystalline quality. The growth direction of these nanowires is parallel to [1 0 0] orientation.     

ZnO-TiO_2核壳纳米线结构及其热稳定性研究

采用热还原法和原子层沉积技术制备了ZnO-TiO_2核壳纳米线,研究沉积厚度、沉积温度及退火对于ZnO-TiO_2核壳纳米线晶化和结构的影响。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、高分辨率透射电镜(HRTEM)等手段对退火前后核壳纳米线进行表征。结果表明:沉积厚度和温度的增加有利于TiO_2壳层发生非晶向晶化的转变;500℃退火提高了TiO_2的结晶性,但可能会使细核壳纳米线(ZnO纳米线直径80 nm)产生波浪形变形,使150℃沉积的非晶TiO_2壳层形成凸出晶粒,并导致其界面处ZnO缺失。     

In situ synthesis and photoluminescence of SiC nanowires by microwave-assisted pyrolysis of methane

A simple method was used to synthesize SiC nanowires directly on quartz plate by microwave pyrolysis of methane. The samples have been characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectroscopy techniques. The results showed that the nanowires are of cubic β-SiC structure with stacking faults. The diameters of SiC nanowires are in the range of 50–200 nm and their lengths up to several tens of microns. The effect of the reaction gas concentration and the reaction temperature on the morphologies of SiC nanowires was also investigated. Two broad photoluminescence peaks at the center wavelength of about 309 and 417 nm were observed at room temperature.     

Synthesis of ultralong Si3N4 nanowires by a simple thermal evaporation method

Large-scale vapor-solid synthesis of ultralong silicon nitride (Si3N4) nanowires was achieved by using simple thermal evaporation of mixture powders of active carbon and monoxide silicon. The products were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. The results suggest that the silicon nitride nanowires have a smooth surface, with lengths of up to several hundreds of microns and diameters of 100-300 nm. A detailed study of both the chemical and structural composition was performed. Such ultralong silicon nitride nanowires demonstrate potential applications as materials for constructing nanoscale devices and as reinforcement in advanced composites.     

Novel dye-sensitized solar cell architecture using TiO_2-coated Ag nanowires array as photoanode

With the aim of reducing series resistance and increasing dye loading, novel dye-sensitized solar cell architecture was designed with TiO_2 nanoparticle-coated Ag nanowires array as the photoanode. Ag nanowire array was prepared by anodic aluminum oxide(AAO) templateassisted electrochemical deposition route. Then, Ag nanowires were coated by TiO_2 nanoparticles in hydrothermal process. The structures of the photoanode were characterized by field emission scanning electron microscopy(FESEM). Ag nanowires are covered by a layer of very fine nanoparticles with a diameter of less than 5 nm. X-ray diffraction(XRD) and selected-area electron diffraction(SAED) show that Ag nanowires have a strong preferred orientation in(220) direction and the TiO_2 coating layer is a polycrystalline structure. With this photoanode, 3.2%conversion efficiency is achieved for the cell sensitized with N3 dye.