化学溶液沉积法制备单分散氧化锌纳米棒阵列

在由溶胶凝胶法制备的纳米ZnO薄膜基底上, 采用化学溶液沉积法制备了单分散、高度取向的ZnO纳米棒阵列膜. 通过控制纳米ZnO薄膜的制备工艺, 可以调节氧化锌纳米棒的直径. 利用FESEM, TEM, HRTEM, SAED和XRD表征了氧化锌纳米棒阵列的形貌和晶体结构. ZnO纳米棒的室温PL谱具有很高的紫外带边发射峰, 在可见光波段无发射峰, 表明该方法制备的ZnO纳米棒晶体结构完整, 晶体中O空位的浓度很低.     

微波固相合成氧化锌纳米棒

通过前驱体的微波固相热分解法快速合成了氧化锌纳米棒, 其直径在60～385 nm之间, 长可达数微米. 前驱体则通过一步室温固相反应制备. 用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能量色散X射线分析(EDX)和透射电子显微镜(TEM)对产物的结构和形貌进行了表征. 同时, 对氧化锌纳米棒的光致发光(PL)性能作了测试, 结果表明在355 nm处有一个明显的近带隙发射峰. 另外, 对比实验表明, 微波辐射在氧化锌纳米棒的形成过程中起了关键性作用, 并对其形成机理进行了初步探讨.     

Sn掺杂ZnO半导体纳米带的制备、结构和性能

在无催化剂的条件下, 利用碳热还原反应气相沉积法制备出了高产率单晶Sn掺杂ZnO纳米带. XRD和TEM研究表明纳米带为结晶完好的纤锌矿结构, 生长方向沿[0001], EDS分析表明纳米带中Sn元素含量约为1.9%. 室温光致发光谱(PL)显示掺锡氧化锌纳米带存在强的绿光发射峰和较弱的紫外发射峰, 谱峰峰位中心分别位于494.8 nm和398.4 nm处, 并对发光机制进行了分析. 这种掺杂纳米带有望作为理想的结构单元应用于纳米尺度光电器件领域.     

1,3-二苯基-2-吡唑啉纳米带的制备及其光波导性质

以1,3-二苯基-2-吡唑啉(DP)为目标化合物, 利用再沉淀方法, 以混合溶剂作为不良溶剂, 制备了形貌均一、宽度约2 μm、厚度200 nm和长度数十微米的一维纳米带状结构. 选区电子衍射结果证实, DP分子在纳米带中因为强的分子间π-π相互作用而沿着晶体[100]方向优势生长. 稳态光谱结果表明, DP纳米带具有不同于分子和体相材料的介观特性. 由于J-聚体在DP纳米带中优势形成, 其480 nm的发射峰与分子和体相材料相比分别红移了30和20 nm. 利用扫描近场光学显微镜进一步发现, 一维DP纳米带类似于天然的亚波长尺度谐振腔, 紫外激发DP分子发射的荧光被限域在DP纳米带中, 沿一维方向传导并在两端耦合输出.     

GaN纳米带、纳米环和Z字结构纳米线在金属镓颗粒上的原位生长及其发光性质

在1050℃氨气和氢气混合气氛中加热金属镓,在镓颗粒表面原位生长出了GaN纳米带、纳米环和Z字结构纳米线．利用激光拉曼光谱仪、扫描电子显微镜和透射电子显微镜对产物进行了表征,结果表明,所得不同形貌GaN纳米结构均为单晶六方纤锌矿结构,纳米带宽度在20～300nm,长达30gm;纳米环直径在5-8gm;Z字结构纳米线的直径约为160nm．研究了反应温度和时间对产物形貌和结构的影响,提出了不同形貌GaN纳米结构的可能形成机理．从GaN纳米结构的发光光谱中观察到了发光峰位于361nm强的紫外光发光和456nm弱的蓝光发光,这两种发光分别起源于GaN宽带隙带边的激子发射和浅的给体向深的局域受体的跃迁．     

三聚磷酸钠辅助水热合成制备氧化锌纳米片

以三聚磷酸钠为表面活性剂,采用水热合成法制备了氧化锌纳米片。采用场发射扫描电镜,透射电镜,紫外可见分光光度计和荧光光谱仪对氧化锌纳米片的显微结构和光学性能进行了表征,并对氧化锌纳米片的形成机理进行了探讨。结果表明：在220 ℃水热反应28 h可得到尺寸大约为600 nm × 500 nm × 50 nm(长×宽×高)结晶良好的六角形氧化锌纳米片,氧化锌纳米片对可见光的反射率超过90%,对紫外光的反射率小于20%,在395 nm附近均存在较强的紫外发射峰。氧化锌纳米片的形成是由于氧化锌晶体的正极面{001}晶面上显露的OH^-悬健部分被具有负电性的磷酸根取代,这种取代的发生,阻碍了溶液中的生长基元Zn(OH)₄^2-在该晶面上叠合,使得本应生长最快的(001)晶面生长受限,所以得到了片状的纳米氧化锌。     

均匀沉淀法制备氧化锌纳米棒

采用均匀沉淀法制备了氧化锌纳米棒,用XRD,TEM,PL等检测手段对样品进行了表征.结果表明:所得样品为长约100 nm,宽约30 nm的纤锌矿结构氧化锌纳米棒,颗粒分布均匀.其在可见光区比紫外区的荧光发射显著增强.     

溶剂热法合成CdS纳米晶及其光学性质研究

以硫脲和醋酸镉为原料,采用溶剂热法在不同的反应介质和温度下合成了CdS纳米晶,比较了单胺与双胺对合成CdS纳米晶形貌的影响。采用透射电镜(TEM)、X射线粉末衍射仪(XRD)和荧光分光光度计(PL)对合成的CdS纳米晶结构和光学性能进行表征。结果表明:反应温度和反应介质对其形貌有影响,在双胺的条件下,60℃时合成了纯相的六方相CdS纳米棒;双胺条件下更易生成纳米棒,且高温下晶体的结晶性更好。PL分析表明,水(溶剂)热法制备的CdS的荧光光谱图与大多数CdS类似,均在440~480 nm和550 nm处存在发射峰,但较宽的发射峰蓝移说明材料的光学性质受到材料形貌和制备方法的影响。     

铝热反应法制备双股类螺旋Zn2SnO4单晶纳米带

综合利用化学气相沉积、铝热反应法、汽-液-固生长法、极性面融合和稳态湍流动力学控制来大量制备双股类螺旋Zn₂SnO₄单晶纳米带. 该材料属于面心立方尖晶石型透明半导体, 在光伏器件和湿度与可燃气体传感器中有着广泛的应用. 扫描电镜、透射电镜、电子衍射、X射线衍射、拉曼光谱以及光发射等技术分析表明所得的双股类螺旋纳米带是由两个独立的Zn₂SnO₄纳米带通过扭曲纠缠和融合而成. 该双股类螺旋纳米带实际上是在轴向具有周期性的超晶格材料. 光致发光测量表明该纳米带在326.1 nm处出现强发射峰, 线宽约为1.5nm. 本研究所采用的综合制备法中的铝热反应法和稳态湍流微扰法可能有助于类似材料的控制制备.     

YVO_4:Eu~(3+)纳米晶的水热合成与发光特性

采用水热法在不同温度下制备了系列YVO4:Eu3+纳米晶。利用X射线衍射、电镜和荧光光谱对前驱体和系列样品的结构、形貌和发光性能进行了研究。XRD研究结果表明:合成的样品均为四方相YVO4,纳米晶的一次性粒径分布在13~44 nm。发射光谱和激发光谱的研究表明:特征发射峰来自于5D0-7FJ跃迁,激发带主要来自于Eu-O和V-O的电荷迁移带,发射强度和激发强度随样品结晶度的提高而增强。对样品5D0-7F2跃迁中来自于不同态的发射峰的相对强度进行了比较和讨论。     

一种在固体基底上制备高度取向氧化锌纳米棒的新方法

采用廉价、低温的方法，在修饰过ZnO纳米粒子膜的ITO基底上成功制备出具有 高长径比、高度取向的ZnO纳米棒阵列，用扫描电子显微镜(SEM)，X射线衍射(XRD) ，高分辨透射电子显微镜(HRTEM)以及拉曼光谱对制备出的ZnO纳米棒的结构和形貌 进行了表征，测试结果表明，ZnO纳米棒是单晶，属于六方晶系，与基底直，上仍 沿(001)晶面择优生长的特征，并且ZnO纳米棒基本上无氧空位的存在，统计结果显 示，水热反应2h后90%以上的ZnO纳米棒直径为120～190nm，长度为4μm     

Zinc oxide prepared by homogeneous hydrolysis with thioacetamide, its destruction of warfare agents, and photocatalytic activity

Zinc sulfide (ZnS) nanoparticles were prepared by homogeneous hydrolysis of zinc sulfate and thioacetamide (TAA) at 80 degrees C. After annealing at a temperature above 400 degrees C in oxygen atmosphere, zinc oxide (ZnO) nanoparticles were obtained. The ZnS and ZnO nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and Brunauer-Emmett-Teller (BET)/Barrett-Joyner-Halenda (BJH) methods were used for surface area and porosity determination. The photocatalytic activity of as-prepared zinc oxide samples was determined by decomposition of Orange II dye in aqueous solution under UV irradiation of 365 nm wavelength. Synthesized ZnO were evaluated for their non-photochemical degradation ability of chemical warfare agents to nontoxic products.     

图案化锥形氧化锌纳米带的原位热氧化法制备与发光性质

采用光刻技术制备出图案的锌膜,所得锌膜与纯氧在700℃氧化反应10 min,在锌膜的表面上原位生长出具有图案的锥形ZnO纳米带阵列,实现了ZnO纳米带生长位置的可控生长。锌膜上得到的锥形ZnO纳米带为单晶六方纤锌矿结构,长度在1～4μm,纳米带根部和顶部的宽度分别在300～700 nm和100～300 nm。提出了锥形ZnO纳米带的可能生长机理。在波长为300nm光的激发下,发现了锌膜上锥形ZnO纳米带具有发光峰位于395 nm弱的紫外光发光和510 nm强的蓝绿光发光,它们分别起源于ZnO宽带隙的激子发射以及表面上离子化氧空位中的电子与价带中光激发的空穴之间的复合。     

The synthesis and optical properties of different zinc oxide nanostructures

The tetrapod-like whiskers (T-ZnO), nanoaeroplanes, nanocombs, nanobelts, bead-like nanoforms and many other forms of hexagonal zinc oxide were synthesized by the chemical deposition process (CVD). From the experimental results it can be seen that the composition of source gases and the speed of oxidation are essential to the growth of each of these morphologies of zinc oxide. By controlling the growth conditions, one novel morphology of ZnO (bead-like nanoform) has been obtained. The ZnO tetrapod-like whiskers were grown without catalysts on the walls of quartz tube. The structure and morphology of the T-ZnO was characterized. All four legs of as-grown ZnO nanotetrapods are needle-like and hexagonal shaped and grow in the ±[0001] direction. The effect of synthesis conditions on the morphology and size T-ZnO was observed. Possible mechanisms of growth were investigated. The lengths of the legs of the tetrapods range from 1 to 15 μm and diameter varying from 0.03 to 1 μm during the synthesis. In the photoluminescence spectra T-ZnO clearly shows two maxima at UV and visible regions. The oxygen impurity, particularly, oxygen flow rates mainly influences on increasing (decreasing) at PL peaks. The maximum near of 590–610 nm (～2 eV), confirming the influence of native defects (oxygen vacancies and interstitials) on the PL intensity and optical quenching exciton peak.     

Surface-enhanced Raman scattering and polarized photoluminescence from catalytically grown CdSe nanobelts and sheets

We have successfully fabricated single-crystalline CdSe nanowires, nanobelts, and sheets by a chemical vapor deposition (CVD) method assisted with laser ablation. The synthesized CdSe nanostructures have hexagonal wurtzite phase as characterized by X-ray diffraction (XRD). CdSe nanobelts can range in length from several tens to a hundred micrometers, in thickness from 40 to 70 nm, and a tapered width which is approximately 3 microm at one end and tapers off to approximately 100 nm at a catalytic gold particle. Both selected area electron diffraction (SAED) and high-resolution transmission electron microscopic (HRTEM) measurements show that the single-crystalline hexagonal belts and sheets grew along the [0.1-1.0] direction with side surface of +/-(0 0 0 1) and top surface of +/-(2 -1 -1 0). While the growth mechanism of nanobelts complies with a combination of vapor-liquid-solid (VLS) and vapor-solid (VS) processes, the formation of sheets is primarily based on the VS mechanism. For comparison, the phonon modes of CdSe nanobelts and bulk powder have been measured by surface-enhanced Raman scattering (SERS) and normal Raman scattering (NRS) spectroscopies with off- and near-resonant excitations. A blue-shift of 2.4 cm(-1) for the longitudinal optical (LO) phonon of CdSe nanobelts, relative to bulk CdSe, is attributed to a lattice contraction in the belt structure, which is confirmed by the XRD measurement. Room-temperature microphotoluminescence (PL) at approximately 1.74 eV from single CdSe nanobelts shows a 3-fold enhancement compared to that from bulk CdSe powder and displays a partial polarization dependence of emission angles.     

ZnO nanobelt arrays grown directly from and on zinc substrates: synthesis, characterization, and applications

In situ growth of ZnO nanobelt arrays from and on zinc substrates (foils and microparticles) has been accomplished by controlled thermal oxidation in the presence of oxygen. The nanobelts grow approximately perpendicular to the Zn substrate surface along the 110 direction of ZnO, which has a thickness of approximately 3-4 nm, a width tapering from about 50 to 300 nm, and a length of approximately 10-20 mum. On the basis of the structural analysis and kinetic studies, a tip-growth mechanism is proposed, which underlines the transport of Zn from the substrate to the growing tip. The ratio of UV to green photoluminescent emissions of the as-synthesized ZnO nanobelt arrays could be controlled by varying the reaction conditions. Sharp UV stimulated emission peak is also observed at moderate threshold excitation intensity ( approximately 0.7 mJ/cm(2)) showing the high quality of the ZnO nanobelts. The ZnO nanobelts array has also been tested for sensing NH(3) gas, and high sensitivity, reversibility, and rapid response have been demonstrated.     

Controlled Synthesis of Sea-urchin-like ZnO Nanomaterials with the Aid of Ethylene Glycol Using a Solvothermal Method

Sea-urchin-like ZnO nanomaterials were successfully synthesized by decomposition of zinc acetate precursor in the presence of sodium hydroxide and ethylene glycol(EG) in an ethanol solution using a solvothermal method at 180 ℃ for 12 h.The crystalline phase and morphology of the resultant nanomaterials were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),selected-area electronic diffraction(SAED) and high-resolution electron microscopy(HRTEM).Interestingly,the sizes and prod length of the samples can be easily tuned by changing the amount of directing agent EG and keeping other reaction conditions unchangeable.On the basis of our experimental outcomes,EG-controlled-nucleation-growth formation mechanism was proposed to correspond for the sea-urchin-like ZnO growth processes.And the photoluminescence(PL) spectra of the as-selected samples were measured at room temperature,presenting two emission peaks centered at～388 and 480 nm.     

Synthesis and evolution of novel hollow ZnO urchins by a simple thermal evaporation process

Delicate hollow ZnO urchins have been fabricated by thermal evaporation of metallic zinc powders in a tube furnace without the use of additive, high temperature, or low pressure. The phase transformation, morphologies, and photoluminescence evolution of the ZnO products were carefully studied and investigated with X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and photoluminescence (PL) spectra. These studies indicated that the growth of hollow ZnO urchins involves the vaporization of Zn powder, solidification of liquid droplets, surface oxidation, sublimation, and self-catalytic growth of one-dimensional nanowires.     

高度取向ZnO单晶亚微米棒阵列的制备与表征

通过低温压热的方法,在经过预先处理长满晶核的SnO2导电玻璃基底上制备出具有高度取向的ZnO亚微米棒阵列.用扫描电子显微镜(SEM)、选区电子衍射(SAED)及X射线粉末衍射(XRD),对制备出的ZnO亚微米棒的结构和形貌进行了表征.SEM测试结果表明,ZnO亚微米棒是六方型的,近乎垂直地长在基底上,棒的直径为400～500 nm,长度约为2 μm. SAED和XRD结果表明,ZnO亚微米棒为单晶,属于六方晶系,并且沿[001]方向择优取向生长.