水浴法制备ZnO纳米棒及其场发射性能

用硝酸锌(Zn(NO3)2·6H2O)与六亚甲基四胺(C6H12N4)以等浓度配制成反应溶液,通过水浴法制备出了形貌可控的棒状ZnO纳米结构,讨论了不同反应浓度及衬底对ZnO表面形貌的影响.样品的XRD和扫描电子显微镜分析结果表明,所得产物均为六方纤锌矿结构,在有晶种层的衬底上制备出的ZnO纳米棒沿(001)方向并垂直于衬底表面生长.随着反应浓度的增加,ZnO纳米棒的直径增大,长径比减小.样品的场发射性能测试表明,反应溶液浓度为0.005 mol/L,以铜膜为晶种层的硅衬底上制备出的场发射阴极具有较好的场发射性能.     

Al掺杂四针状ZnO纳米结构的制备及其光致发光和场发射特性

采用热蒸发法成功制备了Al掺杂四针状ZnO纳米结构(T-AZO),利用扫描电子显微镜、X射线衍射仪、荧光光谱仪和场发射测试系统分别研究了不同Al摩尔分数对T-AZO纳米结构表面形貌、微结构、光致发光谱和场发射特性的影响。实验结果表明:T-AZO纳米结构呈现六角纤锌矿结构,Al掺杂对四针状ZnO纳米结构的形貌产生明显影响并且使紫外发射峰产生蓝移。实验中,当Al掺杂摩尔分数为3%时,场发射性能最好,其开启场强为1.33 V/μm,场增强因子为8 420。     

孔雀石绿在镁铝水滑石负载纳米氧化锌上的快速光降解

用共沉淀法制备Mg-Al水滑石纳米粉,ZnO纳米颗粒均相地覆盖在Mg-Al水滑石表面. 在500 ℃煅烧4 h后,采用XRD和SEM分析晶体结构和形貌. 研究表明在Mg-Al水滑石表面成功地制备了纳米ZnO. 所获得的纳米ZnO光催化剂对孔雀石绿表现出高的光催化降解性能. 归因于ZnO表面的高光催化活性以及Mg-Al水滑石较好的吸附性能,其中Mg-Al水滑石层片结构起了重要作用.     

电化学方法制备ZnO纳米颗粒掺杂类金刚石薄膜及其场发射性能研究

采用液相电化学沉积技术制备了ZnO纳米颗粒掺杂的类金刚石(DLC)薄膜, 研究了ZnO纳米颗粒掺杂对DLC薄膜场发射性能的影响. 利用X射线光电子能谱、透射电子显微镜、Raman光谱以及原子力显微镜分别对薄膜的化学组成、 微观结构和表面形貌进行了表征. 结果表明: 薄膜中的ZnO纳米颗粒具有纤锌矿结构, 其含量随着电解液中Zn源的增加而增加. ZnO纳米颗粒掺杂增强了DLC薄膜的石墨化和表面粗糙度. 场发射测试表明, ZnO纳米颗粒掺杂能提高DLC薄膜的场发射性能, 其中Zn与Zn+C的原子比为10.3%的样品在外加电场强度为20.7 V/μm时电流密度达到了1 mA/cm². 薄膜场发射性能的提高归因于ZnO掺杂引起的表面粗糙度和DLC薄膜石墨化程度的增加.     

Ti/TiO_2包覆ZnO:Tb纳米纤维的光学性质

用电纺丝方法制备了ZnO:Tb纳米纤维.用X-射线衍射、Raman光谱对其形貌做了表征.结果显示,ZnO:Tb纳米纤维为六方纤锌矿结构,Tb掺杂对ZnO的结晶性有影响.利用表面等离激元,通过对纳米纤维表面包覆金属Ti和TiO_2,比较了其光致发光谱,得到在325 nm激发下ZnO:Tb纳米纤维中稀土发光效率低的原因是ZnO和Tb之间不能进行有效的能量传递;包覆TiO_2后能提高稀土发光效率.     

水热法合成ZnO纳米棒图案及其场增强效应

利用水热合成方法在图案化的Au岛上合成了ZnO纳米棒图案,采用的溶液体系为六次甲基四胺和硝酸锌溶液,ZnO纳米棒的基底是ITO导电玻璃上的有序Au岛. 由于ZnO的异相成核速度在Au和ITO基底上具有不同的成核速度,因此ZnO优先生长在成核速度快的Au岛上,同时由于受到了溶液中前驱物种扩散的限制,纳米棒继续生长也被受到了约束. 通过调控六次甲基四胺和硝酸锌的浓度,可以调整不同的图案. 此外,利用X射线衍射、光致发光谱和场发射特性性能对水热合成的ZnO纳米棒图案进行了研究. ZnO纳米棒表现出良好的场增强性     

三维花状氧化锌纳米材料的合成及其光催化性能

采用水热法,以硝酸锌[Zn(NO3)2.6H2O]和氨水(NH3.H2O)为原料制备了三维花状氧化锌纳米材料。采用X射线衍射(XRD)、扫描电镜(SEM)等测试方法研究了样品的成分、形貌和结构。研究结果显示:样品为六方纤锌矿结构的花状ZnO纳米材料。为了评估氧化锌纳米材料的光催化性能,进行了氧化锌纳米材料对有机染料甲基橙的光催化降解实验。实验结果表明,氧化锌纳米结构对甲基橙的光催化降解具有较好的催化作用,催化活性与氧化锌纳米结构的特殊形貌有关系。     

紫外发光增强的石墨烯-氧化锌纳米复合物

采用溶剂热法在相同条件下分别制备了纯ZnO和石墨烯-氧化锌纳米复合物,通过SEM、TEM、拉曼和红外光谱等手段,对纳米复合物样品进行了形貌和结构表征。实验结果显示ZnO纳米颗粒成功地分散在少层石墨烯上。通过对比纯ZnO与复合物的形貌和光致发光谱,发现在没有石墨烯时,ZnO能够择优取向生长成六方棱柱,紫外发光峰弱且宽;在有石墨烯时,ZnO聚集成表面不规则的球形颗粒,紫外发光峰强且窄。上述结果表明ZnO形貌的变化和石墨烯的等离子体效应共同影响了ZnO的紫外发光,但石墨烯的表面等离子体效应起主导作用。     

水热法制备Co掺杂ZnO纳米棒及其光学性能

采用水热法在石英衬底上以Zn(CH3COO)2.2H2O和Co(NO3)2.6H2O水溶液为源溶液,以C6H12N4(HMT)溶液作为催化剂,在较低温度下制备了Co掺杂的ZnO纳米棒。采用X射线衍射(XRD)和扫描电子显微镜(SEM)对所生长ZnO纳米棒的晶体结构和表面形貌进行了表征,考察了Co掺杂对ZnO纳米棒微观结构和对发光性能影响的机制。结果表明:Co掺杂的ZnO纳米棒呈六方纤锌矿结构,具有沿(002)面择优生长特性,Co掺杂使ZnO纳米棒的直径变细;同时室温光致发光(PL)谱检测显示Co掺杂ZnO纳米棒具有很强的近带边紫外发光峰,而与深能级相关的缺陷发光峰则很弱。本研究采用水热法在石英衬底上于较低温度下生长出了具有较高光学质量的Co掺杂ZnO纳米棒。     

准一维深色纳米ZnO的水热方法生长及其结构和光学性能的调变

本文以高纯度金属锌箔为Zn和衬底,利用传统的水热合成方法制备了深色的纳米结构ZnO. 研究发现,改变制备温度可以调变ZnO样品的颜色和光学性能,尤其是提高温度可以显著地降低可见光波段太阳能的活性. 推测这种现象与ZnO纳米棒顶端的尖锥形貌密切相关,这种结构加剧了光在ZnO纳米棒之间的折射和反应. 改善ZnO的光吸收能力对于提升ZnO基太阳电池的效率有重要意义.     

Thermal evaporation synthesis of zinc oxide nanowires

High quality ZnO nanowires were synthesized at high temperature without using heterogenous catalysts. The nanowires had a uniform prismatic shape and were grown in a cacti-like morphology. Characterizations of the products by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy showed that the ZnO nanowires were single crystalline and of high purity. An intensive exciton emission was observed around 3.25 eV from the ZnO nanowires at room temperature. The growth mechanism was discussed based on the experimental conditions and the ZnO crystal growth habits. This growth method can be used to prepare other metal oxide nanowires. PACS 61.46.+w; 81.16.-c; 81.07.De, 81.05.Hd     

Effect of barium doping on the physical properties of zinc oxide nanoparticles elaborated via sonochemical synthesis method

The aim of this work is to study the effect of barium (Ba) doping on the optical, morphological and structural properties of ZnO nanoparticles. Undoped and Ba-doped ZnO have been successfully synthesized via sonochemical method using zinc nitrate, hexamethylenetetramine (HMT) and barium chloride as starting materials. The structural characterization by XRD and FTIR shows that ZnO nanoparticles are polycrystalline with a standard hexagonal ZnO wurtzite crystal structure. Decrease in lattice parameters from diffraction data shows the presence of Ba²⁺ in the ZnO crystal lattice. The morphology of the ZnO nanoparticles has been determined by scanning electron microscopy (SEM). Incorporation of Ba was confirmed from the elemental analysis using EDX. Optical analysis depicted that all samples exhibit an average optical transparency over 80%, in the visible range. Room-temperature photoluminescence (PL) spectra detected a strong ultraviolet emission at 330 nm and two weak emission bands were observed near 417 and 560 nm. Raman spectroscopy analysis of Ba-doped samples reveals the successful doping of Ba ions in the host ZnO.     

Effect of preheating temperatures on microstructure and optical properties of Na-doped ZnO thin films by sol–gel process

The chemical composition, crystalline structure, surface morphology and photoluminescence spectra of Na-doped ZnO thin films with different heat treatment process were investigated by X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy and a fluorescence spectrometer. The results show that preferred orientation, residual stress, average crystal size and surface morphology of the thin films are strongly determined by the preheating temperature. The effects of preheating temperature on microstructure and surface morphology have been discussed in detail. The photoluminescence spectra show that there are strong violet & UV emission, blue emission and green emission bands. The violet & UV emission is ascribed to the electron transition from the localized level below the conduction band to the valence band. The blue emission is attributed to the electron transition from the shallow donor level of oxygen vacancies to the valence band, and the electron transition from the shallow donor level of interstitial zinc to the valence band. The green emission is assigned to the electron transition from the level of ionized oxygen vacancies to the valence band.     

ZnO/SiO2 复合薄膜的光学性能

采用溶胶-凝胶法在玻璃衬底上制备ZnO/SiO₂复合薄膜,分别用XRD、TEM、SEM对样品的结构和形貌进行表征,并研究了不同ZnO含量对复合薄膜透过率及荧光特性的影响。结果表明,样品经500 ℃退火处理生成了SiO₂和ZnO,其晶粒尺寸为18.7 nm,薄膜具有双层结构。复合薄膜的透过率随着其中ZnO含量的增加而降低,禁带宽度减小,光学吸收边红移。样品在355 nm波长激发下产生了384 nm的紫外发射峰和440 nm的蓝光发射带,并随ZnO含量的增加而增强,它们分别来自ZnO的电子-空穴复合发光和缺陷发光,及ZnO/SiO₂复合薄膜双层结构的缺陷发光。     

高质量ZnO微米棒的制备及其光学性质

利用水热法制备ZnO微米棒。醋酸镁[Mg(CH3COO)2.4H2O]、醋酸锌[Zn(CH3COO)2.2H2O]和六次甲基四胺(C6H12N4)以一定比例配置成反应溶液,把反应溶液加热到90℃,反应时间为24h,能够在硅衬底上生长高质量的ZnO微米棒。用扫描电镜(SEM)和X射线衍射仪对ZnO微米棒的晶体结构和表面形貌进行了分析,结果表明,样品为细长条棒状结构,呈现六方纤锌矿结构,长径比可达10∶1,并且在[002]方向择优生长。在样品中并未发现镁离子,它有可能扮演着催化剂的角色。对ZnO微米棒的光致发光性能进行测量,由PL光谱分析可知,样品在384nm处有一个紫外发光峰,半峰全宽为13nm,紫外发光峰强度比可见发光峰强度大的多,样品的质量较好。     

Influence of solution parameters for the fast growth of ZnO nanostructures by laser-induced chemical liquid deposition

ZnO nanorods, nanoneedles, nanoparticles, and nanoballs were synthesized on fused quartz substrates upon irradiation of a droplet of methanolic zinc acetate dihydrate solution by an infrared (IR) continuous wave CO₂ laser for a few seconds. The addition of monoethanolamine and water to the solution improved the alignment of the nanorods and had a significant effect on the volume and morphology of the deposits. An increase of the zinc acetate concentration was found to lead to an increase of the thickness and area covered by the initial ZnO seed layer on which the nanostructures grew. By investigating the crystal structure of the deposits using X-ray and electron diffraction, we were able to show that the nanorods grow along the c axis with a high crystalline quality. Raman and photoluminescence spectroscopy confirmed the high quality of the grown ZnO nanostructures. As a matter of fact, their photoluminescence spectra are dominated by an intense UV emission around 390 nm.     

Induced growth of high quality ZnO thin filmsby crystallized amorphous ZnO

This paper reports the induced growth of high quality ZnO thin film by crystallized amorphous ZnO. Firstly amorphous ZnO was prepared by solid-state pyrolytic reaction, then by taking crystallized amorphous ZnO as seeds (buffer layer), ZnO thin films have been grown in diethyene glycol solution of zinc acetate at 80℃. X-ray Diffraction curve indicates that the films were preferentially oriented [001] out-of-plane direction of the ZnO. Atomic force microscopy and scanning electron microscopy were used to evaluate the surface morphology of the ZnO thin film. Photoluminescence spectrum exhibits a strong ultraviolet emission while the visible emission is very weak. The results indicate that high quality ZnO thin film was obtained.     

Characterization and optical property of ZnO nano-, submicro- and microrods synthesized by hydrothermal method on a large-scale

In the present paper, well-dispersed ZnO nano-, submicro- and microrods with hexagonal structure were synthesized by a simple low temperature hydrothermal process from zinc nitrate hexahydrate without using any additional surfactant, organic solvent or catalytic agent. The phase and structural analysis were carried out by X-ray diffraction (XRD), the morphological analysis was carried out by field emission scanning electron microscopy (FESEM) and the optical property was characterized by room-temperature photoluminescence (PL) spectroscopy. The results revealed the high crystal quality of ZnO powder with hexagonal (wurtzite-type) crystal structure and the formation of well-dispersed ZnO nano-, submicro- and microrods with diameters of about 50, 200 and 500 nm, and lengths of 300 nm, 1 μm and 2 μm, respectively, on a large-scale just using the different temperatures. Room-temperature PL spectrum from the ZnO nanorods reveals a strong UV emission peak at about 360 nm and no green emission band at ∼530 nm. The strong UV photoluminescence indicates the good crystallization quality of the ZnO nanorods. Room-temperature PL spectra from the ZnO submicro- and microrods reveal a weak UV emission peak at ∼400 nm and a very strong visible green emission at 530 nm, that is ascribed to the transition between V_oZn_i and valence band.     

Chemical vapor deposition synthesis of Ge doped ZnO nanowires and the optical property investigation

Ge-doped ZnO nanowires with high quality were prepared with simple chemical vapor deposition method. The morphology, crystal structure and elemental distribution were characterized using SEM (scanning electron microscopy), HRTEM (high resolution transmission electron microscopy) and EDS (energy dispersive spectrometry) mapping approaches. The optical properties were investigated with combination of room-temperature CL (cathode ray luminescence) and variable temperature micro-PL methods. It is found for the first time that a tapered Ge doped nanowire exhibits a thickness-dependent spectrum shift under a cathode-ray excitation, which was interpreted by the electron-lattice interaction model and the band-filling effect of semiconductors. The exciting power dependent emission spectra (lux-luminescent characteristics) at varied temperatures reveal a varied radiative recombination mechanism. At 83 K, free excitons contribute to the emission spectrum, while at 300 K while at 300 K multi-levels related non-radiative transition process largely contributed. The optical property indicates an excellent crystallization of the nanowires with a small amount of defects.     

形貌依赖的ZnO阴极射线发光性质研究

采用溶剂热法,通过调节水和乙醇混合液的比例制备了多种形貌的ZnO微米结构。利用扫描电子显微镜（SEM）对ZnO微米结构的形貌及尺寸进行了观察。采用可以实现纳米级微观区域光谱采集的阴极射线发光（CL）技术,对不同形貌的单个粒子的光谱进行精细表征,获得了位置依赖的ZnO阴极射线发光数据。实验结果表明：ZnO材料的发光性质与形貌有关,由于形貌差异导致其局部结晶质量、界面缺陷、表面电荷分布、表面晶面等方面的差异,几种因素共同作用决定其最终的发光性质。