Growth of ZnO Nanostructures on Metal-Filled Porous Silicons

在多孔Si上使用不同催化剂成功生长ZnO纳米结构。结果表明,Au作催化剂在Si衬底上得到末端呈六角形的ZnO纳米棒,Cu作催化剂在Si(100)和(111)分别上生长出带状和棒状纳米ZnO,Zn作催化剂在Si衬底上则获得ZnO纳米线。Zn催化制备的ZnO纳米线晶面间距为0.283nm,生长方向是[0110],具有结晶较好的六角纤锌矿晶体结构。比较了不同催化剂制备ZnO的光学性能,发现得到Zn催化制备的ZnO纳米线缺陷绿光峰最弱,因此Zn催化生长制备的纳米ZnO结构质量较好。空气中退火后,3种催化剂生长的纳米ZnO的缺陷发光峰位置不变,而强度变弱。     

碘输运剂对CVT法制备ZnSe单晶的性能影响研究

采用I2作为输运剂,以单质Zn和Se为原料运用化学气相输运法制备了ZnSe晶体。比较了不同I2含量下所生长ZnSe晶体的性能,借助XRD、SEM和EDS检测方法分析了ZnSe晶体的结构、形貌和成分。结果表明:I2含量对ZnSe晶体性能具有重要的影响,通过比较3组I2含量所制备的ZnSe晶体,确定出当I2含量为4 mg/cm3时,所生长的ZnSe晶体具有较好的结晶质量,其晶格常数为5.668 nm。测定ZnSe中Zn与Se的原子分数比为1:0.99,且只有1个衍射峰(2θ=27.2°),其晶面指数为(111)。SEM图像表面比较平滑,没有明显气孔。在此条件下,ZnSe晶体的红外透过性能最好,红外透过率为53.07%~62.61%。其他两种I2含量下所生长的ZnSe晶体结晶质量较差,XRD图谱显示有多个衍射峰,SEM图像表面凹凸不平,有明显气泡和孔洞,并且其红外透过率较低。     

一维ZnE（E=S，Se）纳米结构的气相合成

在NiE（E=S，Se）纳米粒子辅助下，采用CVD方法，在NiE（E=S，Se）-Zn系统中成功生长出立方闪锌矿结构一维ZnE（E=S,Se）纳米线。生长的ZnSe和ZnS纳米线长度达几十微米，具有接近理想化学计量比的成分和较高的结晶质量。研究表明，ZnE纳米线生长过程中，ZnNi合金充作实际的催化剂，生长遵循氧化还原反应助VLS机理。基于此机理，通过调控NiE纳米粒子的尺寸可以有效控制ZnE纳米线的直径。     

Effect of Sn on Microstructure and Electrochemical Properties of Mg Alloy Anode Materials

使用硼粉为硼源,硅和镍为催化剂反应成功制备出硼纳米线.硼纳米线的直径为50～100 nm,其长度为几微米.实验表明硅可以促进硼纳米线的生长.在纳米线的生长过程中使用Ni(NO3)2或NiSO4作为镍源,前者催化效率更高.此外,在硼纳米线生长前先合成NixBy催化剂,与同时加入反应物相比较,催化效果得到提高.     

基于紫外光辐照法制备CuSe/ZnSe核壳结构纳米粒子

本文成功制备出以CuSe为核心、ZnSe为壳层,具有核壳结构的CuSe/ZnSe纳米粒子。首先采用回流冷凝法制备出CuSe纳米粒子（NPs）。然后,采用一种简单、快速的光化学方法即紫外光辐照法,室温下在CuSe NPs外包覆ZnSe壳层,最终得到CuSe/ZnSe核壳结构纳米粒子。利用X射线衍射(XRD)、能量色散谱仪(EDS)、透射电镜(TEM)、高分辨透射电镜(HRTEM)和光致发光光谱(PL)对合成的CuSe/ZnSe核壳NPs进行了表征。结果分析表明,合成的CuSe纳米粒子具有六方相结构,粒径平均大小在12 nm。制备出的CuSe/ZnSe纳米粒子的核壳结构清晰,生长的ZnSe壳层为立方闪锌矿结构,粒径大小约为15~45 nm。通过ZnSe壳层的包覆使CuSe在475 nm处产生蓝光发射,同时荧光强度显著增强。     

聚合物先驱体热解制备超长SiC纳米线

采用聚合物先驱体热解技术,以聚合物先驱体-聚碳硅烷(Polycarbosilane,PCS)为原料,在催化剂辅助作用下,于1200℃热解制备出超长碳化硅(SiC)纳米线.采用电子能量散射(EDS)、扫描电镜(SEM)、透射电镜(TEM)和x射线衍射(XRD)等分析手段对SiC纳米线进行了表征.结果表明,所制备的纳米线为高结晶性β-SiC,纳米线直径约为30 nm～300 nm,长度可达数毫米.利用.气-固"生长机制对SiC纳米线的生长过程进行了分析.     

Zn0.95Co0.05O纳米线和纳米管的电泳沉积法可控合成（英文）

以阳极氧化铝为模板通过电泳沉积法制备Zn0.95Co0.05O纳米线和纳米管,并对电泳沉积法制备纳米线(管)的机理进行研究。系统的结构表征表明所得的纳米管和纳米线是由8～15nm的纤锌矿纳米晶构成的多晶结构,Co2+离子以代位掺杂形式掺入晶格,取代了晶格中的Zn2+离子。磁性表征显示制备的纳米线和纳米管具有室温铁磁性。由于Co在纳米线(管)中表面择优分布,纳米管的磁性明显高于纳米线。     

Zn_(0.95)Co_(0.05)O纳米线和纳米管的电泳沉积法可控合成(英文)

以阳极氧化铝为模板通过电泳沉积法制备Zn0.95Co0.05O纳米线和纳米管,并对电泳沉积法制备纳米线(管)的机理进行研究。系统的结构表征表明所得的纳米管和纳米线是由8～15nm的纤锌矿纳米晶构成的多晶结构,Co2+离子以代位掺杂形式掺入晶格,取代了晶格中的Zn2+离子。磁性表征显示制备的纳米线和纳米管具有室温铁磁性。由于Co在纳米线(管)中表面择优分布,纳米管的磁性明显高于纳米线。     

原位自生SiC纳米线掺杂SiOC陶瓷粉体的制备与介电性能（英文）

以二茂铁为催化剂,催化裂解陶瓷聚合物先驱体制备了原位自生SiC纳米线掺杂的SiOC陶瓷粉体。SiC纳米线为堆垛方向为111的β相单晶体,直径为10～100 nm,长度可达数微米,均匀分布在SiOC粉体中。基于SiC纳米线微观结构分析,探讨了纳米线的生长机制。研究了复合陶瓷粉体的介电性能。结果发现,SiC纳米线含量可调控复合粉体的电性能,较高含量纳米线可赋予复合粉体较高的介电实部与虚部。     

原位自生SiC纳米线掺杂SiOC陶瓷粉体的制备与介电性能

以二茂铁为催化剂,催化裂解陶瓷聚合物先驱体制备了原位自生SiC纳米线掺杂的SiOC陶瓷粉体。SiC纳米线为堆垛方向为<111>的β相单晶体,直径为10-100nm,长度可达数微米,均匀分布在SiOC粉体中。基于SiC纳米线微观结构分析,探讨了纳米线的生长机制。研究了复合陶瓷粉体的介电性能,结果发现,SiC纳米线含量可调控复合粉体的电性能,较高含量纳米线可赋予复合粉体较高的介电实部与虚部。     

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.     

Fe:ZnSe semiconductor nanocrystals: Synthesis, surface capping, and optical properties

Water-soluble Fe-doped ZnSe (Fe:ZnSe) nanocrystals (NCs) were synthesized by aqueous synthesis approach using thioglycolic acid (TGA) as capping agent. The undoped ZnSe and Fe:ZnSe NCs were well retained in the zinc blende structure, and the Fe dopants were well doped into the ZnSe NCs, as confirmed by X-ray photoelectron spectroscopy (XPS). The lattice constant of Fe:ZnSe NCs decreases slightly by the introduction of Fe, and Fe:ZnSe NCs exhibit a uniform size distribution with average grain size of ∼5 nm. The thioglycolic acid (TGA) was successfully capped on the surface of Fe:ZnSe NCs, confirmed by Fourier-transform-infrared (FT-IR) spectroscopy. The absorption edges of pure ZnSe and Fe:ZnSe NCs are blue-shifted compared to that of corresponding bulk ZnSe, indicating the quantum confinement effect, and the absorption edge of Fe:ZnSe NCs shows a slightly red shift with respect to the pure ZnSe NCs. The as-prepared Fe:ZnSe NCs exhibits an emission peak at ∼425 nm, and the photoluminescence (PL) intensity of the NCs has the maximum value when the Fe-doping concentration reaches 1.0 at%. It is of interest to note that the concentration quenching effect appears when the Fe-doping concentration is larger than 10.0 at%, and the underlying physical mechanisms were discussed.     

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.     

Zn-catalytic growth and photoluminescence properties of branched MgO nanostructures

Mass production of uniform MgO nanostructures has been achieved by a thermal evaporation method. X-ray diffraction （XRD） analyses show the product is composed of pure single-crystalline MgO. Scanning electron microscopy （SEM） and transmission elecwon microscopy （TEM） characterizations show that the MgO branched nanostructures consist of many sfim nanowires growing from the thick MgO rods. The as-synthesized nanowires have a length of several tens of microns and a diameter of several tens of nanometers. The preferred growth direction of the nanowires is [001]. Many nanowires are found to have a dendritic structure and temperature grade is thought to be the main cause of the growth of this structure. Zn nanoparticles scattered on the surface of the MgO rods are thought to be the catalyst of the VLS （vapor-liquid-solid） growth of the MgO nanowires. Room-temperature photoluminescence measurements show that the synthesized MgO nanostructures have a strong emission band at 401 nm and a weak emission band at 502 nm.     

Sublimation sandwich route to ultralong zinc-blende ZnSe nanowires and the cathodoluminescence properties of individual nanowires

Sublimation sandwich method (SSM) was developed to fabricate ZnSe nanowires assisted by Au-catalytic vapor-liquid-solid (VLS) process. The ZnSe nanowires have zinc-blende structure and the length is ultralong, up to tens of micrometers. High-resolution transmission electron microscopic (HRTEM) investigations reveal that there are two types of nanowires: well crystalline nanowires and poor crystalline nanowires with high density of bulk defects e.g. stacking faults, dislocations and twinning defects. The cathodoluminescence spectra indicate significant difference in optical properties of these two types of nanowires. We deduce that V_Zn and Zn_i are the main reason for the deep defects related green-red emission observed in well crystalline nanowires, while the bulk defects in the poor crystalline nanowires should be responsible for the deep defects related emissions centered at 515 and 604 nm.     

Simple hydrothermal synthesis and sintering of Na0.5Bi0.5TiO3 nanowires

Single-crystalline Na_0.5Bi_0.5TiO₃ (NBT) nanowires, with diameters of 100 nm and lengths of about 4 μm, were synthesized by using a simple hydrothermal method. Phase composition, morphology and microstructure of the as-prepared powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The effects of reaction temperature and reaction time on precipitation of the NBT nanowires were investigated. It was found that reaction time significantly influenced the growth behavior of the powders in the hydrothermal system. Based on the experimental results, the one-dimensional (1D) growth mechanism of the NBT was governed by a dissolution-recrystallization mechanism. NBT ceramics derived from the nanowires showed typical characteristics of relaxor ferroelectrics, with diffuseness exponent γ of as high as 1.73.     

表面修饰层厚度对Fe:ZnSe纳米晶光学性能的影响

利用硫代乙醇酸作为稳定剂在水相中合成了Fe:ZnSe/ZnS核/壳结构半导体纳米晶,研究了表面修饰层(壳层)厚度对产物光学性能的影响。XRD和UV-Vis吸收谱表明,合成的半导体纳米晶为核壳纳米晶,呈立方闪锌矿结构。TEM结果表明,产物分散性较好,尺寸均一,呈球形。PL结果表明,适当厚度的ZnS壳层能有效钝化Fe:ZnSe纳米晶表面的非辐射复合位点,当壳层过厚时,ZnS壳层产生的非辐射复合缺陷会导致PL强度下降。     

Low-temperature synthesis of novel ZnO nanowire microspheres on silicon substrates

Microspheres covered with ZnO nanowires were fabricated by oxidative evaporation of pure zinc powder without catalyst at 450℃. X-my diffraction （XRD） demonstrates that the as-obtained sample can be indexed to high crystaUinity with wurtzite structure. The structural features associated with different growth stages were monitored using scanning elec- tron microscope （SEM）, which described the direct observation nucleation and growth process. Meanwhile, room temperature photoluminescence （PL） spectrum showed a UV emission at -388 nm and a broad green emission at -505 nm. The ZnO nanowires with the self-catalyzed growth mechanism were discussed in detail.     

一步阳极氧化法制备氧化铝纳米线及其形成机理

采用一步恒压阳极氧化法在草酸电解液中制备氧化铝纳米线,用扫描电子显微镜和X射线衍射仪等对阳极氧化后产物的形貌、晶相进行了分析,研究了氧化电压、反应温度和电解质浓度对氧化产物形貌的影响。结果表明,纳米线的最佳制备条件为40℃、40 V、0.1 mol/L的草酸电解液。新制备的纳米线为无定形结构,在800℃煅烧60 min后转变为立方相氧化铝。同时根据实验结果,从反应界面的温度分布角度,对氧化铝纳米线的形成机理进行了探讨。