Properties of nano-ZnO/poly(vinyl alcohol)/poly(ethylene oxide) composite thin films

A series of poly(vinyl alcohol)/nano-ZnO composites were prepared by dispersing nano-ZnO in aqueous solutions containing mixtures of the biodegradable polymers poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO), and composite thin films were prepared by casting. The introduction of nano-ZnO into PVA/PEO mixed solutions significantly decreased the resistivity of the solutions. Ultraviolet absorption, thermal behaviour and visco-elastic properties of the thin films were determined as a function of nano-ZnO content up to 15 wt%. Optimum film properties were obtained with 1 wt% nano-ZnO, higher proportions of nano-ZnO resulting in agglomeration of ZnO particles and deterioration in film properties. The Forouhi and Bloomer model was used for the modelling of ZnO thin films.     

Toxicity of zinc oxide nanoparticles to zebrafish embryo: a physicochemical study of toxicity mechanism

The biological impact of engineered nanomaterials released into the aquatic environment is a major concern. In this work, the properties of ZnO nanoparticles (nano-ZnO, 30 nm) were characterized in a water suspension (E3 medium), and a zebrafish 96-h post fertilization (hpf) embryo–larval test was performed to assess the toxicity of nano-ZnO suspension. Nano-ZnO was found to readily form aggregates with different sizes; small aggregates (142.4–517.7 nm) were still suspended in E3 medium, but large aggregates (>1 μm) quickly deposited on the bottom of 24-well plates; nano-ZnO was partially dissolved to Zn species (Zn_(dis)) in E3 medium. In the nano-ZnO suspension, small aggregates, Zn_(dis), and large aggregates might jointly exert influence on the development of zebrafish embryos. The embryo toxicity test revealed that nano-ZnO killed zebrafish embryos (50 and 100 mg/L), retarded the embryo hatching (1–25 mg/L), reduced the body length of larvae, and caused tail malformation after the 96 hpf exposure. Zn_(dis) only partially contributed to the toxicity of nano-ZnO. This research highlights the need to further investigate the ecotoxicity of nano-ZnO in the water environment.     

Structural properties of the donor indium in nanocrystalline ZnO

The structural properties of the nanocrystalline semiconductor ZnO (nano-ZnO) doped with the donor Indium were investigated by perturbed γγ angular correlation spectroscopy (PAC) and extended X-ray absorption fine structure measurements (EXAFS). Up to an average concentration of one In atom per nanocrystallite, PAC measurements show that about 12% of the ¹¹¹In atoms are incorporated on substitutional Zn sites. At higher In concentrations, new In defect complexes are visible in the PAC spectra, which dominate the spectra if the average In concentration exceeds one In atoms per nanocrystallite. In addition, the local environment of Zn and In atoms in In doped nano-ZnO was investigated by EXAFS. The measurements at the K edge of Zn show that the crystal structure of nano-ZnO corresponds to bulk ZnO. In heavily In doped nano-ZnO the EXAFS experiments at the K edge of In exhibit an expansion of the first O shell about the In site. Since about four O atoms are detected in this first shell a substitutional incorporation of the In atoms in the ZnO lattice is suggested. The second shell to be occupied by Zn atoms as well as higher shells are almost invisible, which might have the same microscopic origin as the occurrence of defect complexes observed by PAC.     

Surface modification of zinc oxide nanoparticle by PMAA and its dispersion in aqueous system

Commercial zinc oxide nanoparticles were modified by polymethacrylic acid (PMAA) in aqueous system. The hydroxyl groups of nano-ZnO particle surface can interact with carboxyl groups (COO-) of PMAA and form poly(zinc methacrylate) complex on the surface of nano-ZnO. The formation of poly(zinc methacrylate) complex was testified by Fourier-transform infrared spectra (FT-IR). Thermogravimetric analysis (TGA) indicated that PMAA molecules were absorbed or anchored on the surface of nano-ZnO particle, which facilitated to hinder the aggregation of nano-ZnO particles. Through particle size analysis and transmission electron micrograph (TEM) observation, it was found that PMAA enhanced the dispersibility of nano-ZnO particles in water. The dispersion stabilization of modified ZnO nanoparticles in aqueous system was significantly improved due to the introduction of grafted polymer on the surface of nanoparticles. The modification did not alter the crystalline structure of the ZnO nanoparticles according to the X-ray diffraction patterns.     

超声喷雾共沉淀法制备Eu3+掺杂纳米ZnO粉体

采用超声喷雾共沉淀法技术,以Zn(NO3)23·6H2O和(NH4)CO3,为前驱体制备了ZnO纳米粉体以及ZnO:Eu粉体.研究了超声喷雾条件、反应时间以及化学组分对ZnO纳米粉体的形貌和尺寸的影响,着重研究了氢氧化锌脱水生成ZnO纳米粉体的化学处理条件.在ZnO中掺入Eu3+离子,研究了不同Eu3+掺杂量对纳米Zn...     

纳米ZnO颗粒在阳极Al2O3模板中的强光致发光研究

用金属醇盐水解法在阳极Al2O3模板的有序孔洞中生长了纳米量级的ZnO颗粒,并用扫描电子显微镜（SEM）和高分辨电子显微镜（HRTEM）对其形貌进行观察。对纳米ZnO/多孔阳极Al2O3模板组装体的光致发光谱进行测量,将组装体中ZnO颗粒的发光强度与常规方法制备的纳米ZnO颗粒发光强度做了比较,就发光强度提高的原因进行了讨论。     

溶胶-凝胶法制备纳米氧化锌及其光催化性能

采用溶胶-凝胶法制备ZnO纳米粒子,采用X-射线衍射仪(XRD)、透射电镜(TEM)等手段对样品进行了表征;以纳米氧化锌作为光催化剂,利用300W高压汞灯为光源对甲基橙溶液进行光催化实验。实验结果表明:以汞灯为光源,纳米ZnO为催化剂对甲基橙溶液进行光催化时,纳米ZnO的最佳投加量为0.1020g。     

真空冷冻干燥结合微乳液法制备纳米ZnO

真空冷冻干燥技术结合反相微乳液法制备了纳米ZnO粉体。利用XRD、TEM及表面积分析仪对制备过程、粉体的结构、形貌、比表面积、孔容进行了表征。探讨了煅烧温度、干燥方式及真空冷冻干燥的主要参数对纳米ZnO的影响。结果表明:该方法较常规方法制备的纳米ZnO粒径小(平均19nm)、分散性好、比表面积大(567.9m2.g-1),对亚甲基蓝溶液的降解(降解率98.6%)具有较高的光催化活性。     

Nanostructured ZnO synthesis and its application for effective disinfection of <Emphasis Type="Italic">Escherichia coli</Emphasis> micro organism in water

Nanostructured ZnO photo catalyst was synthesized by precipitation method and was applied in conjunction with 355 nm pulsed laser irradiation for effective disinfection of the water contaminated with Escherichia coli micro organism. The morphological studies using X-Ray Diffractometer (XRD) and Transmission Electron Microscope (TEM) were carried out on the synthesized nano-ZnO, and these studies indicated that the catalyst has the crystallographic structure of hexagonal wurtzite and has the grain size of around 20–40 nm. The bacteria decay rate constants were estimated for nine different concentrations of nano-ZnO in infected water. The parametric optimization was carried out, and we could reach the decay rate constant as high as 0.24 min_,⁻¹ which is higher than micro-structured ZnO and the familiar TiO₂ photo catalysts under similar experimental condition.     

聚合物纳米复合电解质(PEO)8-ZnO-LiClO4微结构及电导率研究

以聚氧化乙烯(PEO)为基质,成功制备出纳米ZnO掺杂的(PEO)₈-ZnO-LiClO₄离子导电聚合物电解质,并利用多种实验技术,包括扫描电子显微镜、X射线衍射(XRD)、傅里叶变换红外光谱和正电子湮没寿命谱(PALS),系统地研究了纳米ZnO与基质间相互作用及其对聚合物链段运动、纳米尺度自由体积、离子输运和复合电解质电导率的影响.实验结果发现,纳米ZnO的掺杂使聚合物电解质的离子电导率得到了大幅度提高,当ZnO与PEO质量比为6%时达到最大,(PEO)₈-ZnO-LiClO₄的电导率为1.82×10^-4 S ·cm^-1,比(PEO)₈-LiClO₄的电导率(6.58×10^-5 S ·cm^-1)提高了大约一个数量级.XRD结果显示,纳米ZnO的加入降低了PEO的结晶性,增加了锂离子传输的非晶相,从而提高了电导率.离散PALS测量结果表明,随着纳米ZnO的加入,复合电解质的自由体积、浓度和相对自由体积分数f_r均增加.连续PALS分析揭示了自由体积的分布由一个峰劈裂成两个峰,表明纳米ZnO的掺杂对聚合物的微结构有很大影响.基于实验测量的f_r和离子电导率,研究了离子导电机理.研究发现, f_r与电导率之间存在一个直接关系,即f_r越大,越有利于锂离子的传输,导致电导率越大.这个结果支持聚合物电解质导电的自由体积理论. 关键词： 正电子湮没寿命谱 聚合物纳米复合电解质 离子电导率 自由体积     

氧化锌及纳米氧化锌研究进展

ZnO是一种重要的直接宽带隙半导体,室温下禁带宽度为3.37eV,激子束缚能为60meV,对于开发蓝绿、蓝光、紫外等多种发光器件有巨大潜力.纳米ZnO表现出与体材料明显不同的电学、磁学、光学、化学等性质,是目前纳米材料的研究热点之一.本文介绍了ZnO和纳米ZnO的一些基本性质,综述了近年来纳米ZnO的合成以及应用等方面研究的一些进展.     

Structure of nanocrystalline ZnO up to 85 GPa

The structure of nanocrystalline and bulk polycrystalline ZnO were examined up to 85 GPa and 50 GPa, respectively using synchrotron X-rays and diamond anvil cells at ambient conditions. The transition from the wurtzite to the rock salt phase in the nano-ZnO takes place at 10.5 GPa; this transition pressure is 1.5 GPa higher than in bulk ZnO. A large volume collapse of about 17.5% is observed during the transition in both systems. The rocksalt phase is stable and no structural transitions are observed for both compounds at higher pressures up to the experimental limit. On decompression the rocksalt phase is found to co-exist with the wurtzite phase at ambient conditions for the nano-ZnO.     

Preferential Alignment of Hydroxyapatite Crystallites in Nanocomposites with Chemically Disintegrated Silk Fibroin

Hydroxyapatite (HAp) nanocrystals were prepared at room temperature by a coprecipitation method from Ca(OH)₂ and H₃PO₄, in the presence of chemically disintegrated silk fibroin (SF). Adsorbed amounts of cations on SF and crystallinity of HAp in the composite were increased by the chemical disintegration of SF higher order structure. Preferential alignment of c-axis of HAp crystallites along the longitudinal direction of ca. 150nm SF fibril was observed. These changes due to disintegration of SF were discussed in terms of the chemical interaction between HAp and SF. The resulted composite with preferential alignment of HAp nanocrystals is a good candidate as a starting material for bone substitutes.     

ZnO/Zn界面对纳米ZnO薄膜光学性质的影响

采用氧等离子体辅助电子束蒸发金属Zn后低温退火的方法制备纳米ZnO薄膜。利用X射线衍射(XRD)谱、拉曼(Raman)谱、X射线光电子能谱(XPS)以及光致发光(PL)谱等手段,分析了退火温度及ZnO/Zn界面对样品的结构和发光性质的影响。Raman结果表明随着退火温度的升高,界面模式(Es)振动减弱并向低波数方向移动。当退火温度为400℃时,界面振动消失,Zn全部转化成具有六方纤锌矿结构的ZnO,得到化学配比的纳米ZnO薄膜。PL谱表明,经400℃退火处理的样品紫外发射最强,发光性质最好。     

Structural,magnetic and XPS studies of Sn0.95Co0.05O2-0.05 and Sn0.95Fe0.05O2-0.05 nanoparticles

Structural, microstructural, X-ray photoemission spectra (XPS) and magnetic properties of transition metal ion [5 mol% of Co (SC5) and Fe (SF5)]-doped SnO₂ nanoparticles have been studied. The SC5 and SF5 nanoparticles were synthesized by a chemical route using polyvinyl alcohol as surfactant. The doped SnO₂ crystallites were found to exhibit a tetragonal rutile structure and the average grains size was measured by the Scherer relation of X-ray diffraction. Transmission electron micrographs showed that the average grain size of SC5 is smaller than SF5. SC5 nanoparticles showed strong ferromagnetic behaviour but SF5 exhibited an F-centre exchange (FCE) mechanism. Temperature-dependent magnetization showed the values of phase transition temperature. XPS confirmed the presence of Sn–O–Co and Sn–O–Fe bonds in these SC5 and SF5 nanoparticles. The oxidation states of Sn, Co and Fe were found to be +4, +2 and +2, respectively, while the core level XPS peaks of Sn 3d, O 1s, Co 2p and Fe 2p were analyzed.     

FISSION MEASUREMENT ON 5.5 TO 21.7MeV/A 28Si+197Au SYSTEM (Ⅱ) ANGULAR DISTRIBUTION OF ICF AND SF

According to the distribution of linear momentum transfer (lmt) obtained from the correlation measurement of fission partner,the events of Incomplete Fusion Fission (ICF) and Sequential Fission (SF) were distinguished.The fission angular distributions of both ICF and SF were obtained,respectively.
With calculating the moment of inertia by Cassinian Ovaloid as the fission shape, the angular distributions were fitted by current procedure.The spins of fission nuclei corresponding to ICF and SF are extracted.The relation between spins and bombarding energy is discussed.Besides,the angular distribution in coincidence with complex particles is discussed.     

Ionic liquid-assisted synthesis of carbon nanotube/platinum nanocomposites

A novel solution-enhanced dispersion by supercritical CO₂ (SEDS) was employed to prepare silk fibroin (SF) nanoparticles. The resulting SF nanoparticles exhibited a good spherical shape, a smooth surface, and a narrow particle size distribution with a mean particle diameter of about 50?nm. The results of X-ray powder diffraction, thermo gravimetry-differential scanning calorimetry, and Fourier transform infrared spectroscopy analysis of the SF nanoparticles before and after ethanol treatment indicated conformation transition of SF nanoparticles from random coil to ??-sheet form and thus water insolubility. The MTS assay also suggested that the SF nanoparticles after ethanol treatment imposed no toxicity. A non-steroidal anti-inflammatory drug, indomethacin (IDMC), was chosen as the model drug and was encapsulated in SF nanoparticles by the SEDS process. The resulting IDMC?CSF nanoparticles, after ethanol treatment, possessed a theoretical average drug load of 20%, an actual drug load of 2.05%, and an encapsulation efficiency of 10.23%. In vitro IDMC release from the IDMC?CSF nanoparticles after ethanol treatment showed a significantly sustained release over 2?days. These studies of SF nanoparticles indicated the suitability of the SF nanoparticles prepared by the SEDS process as a biocompatible carrier to deliver drugs and also the feasibility of using the SEDS process to reach the goal of co-precipitation of drug and SF as composite nanoparticles for controlled drug delivery.     

The sensitivity and dynamic response of field ionization gas sensor based on ZnO nanorods

Field ionization gas sensors based on ZnO nanorods (50–300 nm in diameter, and 3–8 μm in length) with and without a buffer layer were fabricated, and the influence of the orientation of nano-ZnO on the ionization response of devices was discussed, including the sensitivity and dynamic response of the ZnO nanorods with preferential orientation. The results indicated that ZnO nanorods as sensor anode could dramatically decrease the breakdown voltage. The XRD and SEM images illustrated that nano-ZnO with a ZnO buffer layer displayed high c-axis orientation, which helps to significantly reduce the breakdown voltage. Device A based on ZnO nanorods with a ZnO buffer layer could distinguish toluene and acetone. The dynamic responses of device A to the NO _x compounds presented the sensitivity of 0.045 ± 0.007 ppm/pA and the response speed within 17–40 s, and indicated a linear relationship between NO _x concentration and current response at low NO _x concentrations. In addition, the dynamic responses to benzene, isopropyl alcohol, ethanol, and methanol reveals that the device has higher sensitivity to gas with larger static polarizability and lower ionization energy.     

纳米ZnO墨水的溶剂及浓度优化及其在钙钛矿太阳能电池中的应用

纳米金属Zn O作为界面缓冲材料能够有效提高基于有机金属卤化物-甲基碘化铵的钙钛矿(PVSK)太阳能电池的水氧稳定性,是溶液制备高稳定性钙钛矿太阳能电池的一个关键技术。而在器件的制备过程中,Zn O分散溶剂的渗透可能导致下层钙钛矿薄膜的结构物性发生变化,从而对器件性能造成显著的影响。为解决该问题,本文详细分析了不同极性有机溶剂对Zn O分散性的影响,研究了不同溶剂对PVSK/PCBM薄膜的吸收光谱和晶体结构的影响,最终获得了甲醇-正丁醇混合溶剂的体积比为1∶1、Zn O质量浓度为10 mg·m L-1的优化分散体系,为进一步开展全溶液法制备钙钛矿太阳能电池提供了重要指导。     

High-affinity integration of hydroxyapatite nanoparticles with chemically modified silk fibroin

Hydroxyapatite (HA)-based nanocomposites were prepared by a co-precipitation method with silk fibroin (SF) serving as organic matrix. Silk fibroin was chemically modified with an alkali solution or an enzyme attempting to improve the interface between the mineral and the organic matrix. The influences of the alkali and enzyme pretreatments on microstructure and physicochemical properties of HA–SF composite were examined and compared. The results reveal that both the two kinds of pretreatments facilitate the formation of highly ordered three-dimensional porous network throughout the composites, increase the microhardness of the composite, and promote the preferential growth of HA crystallites along c-axis. Among all the as-prepared samples, the composite containing the enzyme pretreated SF shows desirable hierarchical microstructure with higher degree of organization and more uniform pore size distribution. Due to the enzyme pretreatment, HA crystallites undergo obvious changes in morphology from rod-like to␣whisker-like and in crystal growth towards more apparent epitaxy along c-axis. The alkali pretreatment induces the stronger chemical interactions between HA and SF and thus to strengthen the inorganic–organic interfacial adhesion. The newly developed HA–SF composites are expected to be attractive biomedical materials for bone repair and remodeling.