均匀沉淀法制备碳纳米管/氧化锌复合材料的研究

采用均匀沉淀法制备了碳纳米管(CNTs)负栽氧化锌(ZnO)粒子复合材料,并利用扫描电子显微镜(SEM)、X光衍射分析(XRD)以及热失重分析(TGA)手段对复合粒子进行了表征.研究结果表明:锌离子浓度取0.4mol/L至1.0mol/L时,所得复合材料中的氧化锌粒子大小均匀细小,分散性较好,形貌以粒状为主,大小在40nm左右;纳米氧化锌粒子与碳纳米管结合力较强,CNTs/ZnO复合材料在超声作用下能够稳定存在;反应时间越长,氧化锌粒子含量越高,晶粒越大;热解温度越高,热解时间越长,氧化锌晶粒尺寸越大.     

不同形貌聚苯胺/氧化锌复合材料的制备与光催化性能EI北大核心CSCD

通过水热法制备了球形、棒状和花形的纳米氧化锌;并利用原位聚合法制备了对应形貌的氧化锌/聚苯胺复合材料。用X射线衍射(XRD)、热重分析(TG-DTG)和扫描电镜(SEM)等测试手段,对氧化锌及复合物进行了结构表征。以次甲基蓝为模拟污染物,在紫外灯下考察了复合物材料的光催化性能和动力学特征。结果表明,聚苯胺(PANI)/氧化锌(ZnO)复合材料的光催化性能远高于纯纳米ZnO,而不同形貌的PANI/ZnO其光催化降解效率也不同,依次为球形>棒状>花形;PANI/ZnO(球形)的失水温度和分解温度与纯PANI相比分别提高了123.3℃和47.6℃。光催化动力学研究表明,以球形和棒状氧化锌为原料制备的PANI/ZnO复合材料符合一级动力学,PANI/ZnO(花形)复合物符合二级动力学。     

不同形貌聚苯胺/氧化锌复合材料的制备与光催化性能

通过水热法制备了球形、棒状和花形的纳米氧化锌;并利用原位聚合法制备了对应形貌的氧化锌/聚苯胺复合材料。用X射线衍射(XRD)、热重分析(TG-DTG)和扫描电镜(SEM)等测试手段,对氧化锌及复合物进行了结构表征。以次甲基蓝为模拟污染物,在紫外灯下考察了复合物材料的光催化性能和动力学特征。结果表明,聚苯胺(PANI)/氧化锌(ZnO)复合材料的光催化性能远高于纯纳米ZnO,而不同形貌的PANI/ZnO其光催化降解效率也不同,依次为球形>棒状>花形;PANI/ZnO(球形)的失水温度和分解温度与纯PANI相比分别提高了123.3℃和47.6℃。光催化动力学研究表明,以球形和棒状氧化锌为原料制备的PANI/ZnO复合材料符合一级动力学,PANI/ZnO(花形)复合物符合二级动力学。     

无机纳米ZnO或蒙脱土颗粒掺杂对低密度聚乙烯介电性能的影响

选择在低密度聚乙烯（LDPE）中掺杂无机纳米ZnO和蒙脱土（MMT）颗粒,探讨不同形态无机纳米颗粒对LDPE介电性能的影响。利用熔融共混法配合不同冷却方式制备不同结晶形态的纳米ZnO/LDPE和MMT/LDPE复合材料。通过FTIR、偏光显微镜（PLM）、SEM、DSC和热刺激电流（TSC）对试样进行表征,并。研究了纳米ZnO/LDPE和MMT/LDPE复合材料的交流击穿特性,结果表明：掺杂适当质量分数并经表面修饰的无机纳米颗粒可有效的避免其团聚现象,提高纳米ZnO/LDPE和MMT/LDPE复合材料的结晶速率,使结晶结构更完善,同时无机纳米颗粒掺杂使LDPE的陷阱密度和深度均有所增加,载流子入陷在试样内部形成界面"局域态"。经油冷却方式制备的纳米ZnO/LDPE和MMT/LDPE复合材料击穿场强比空气自然冷却分别高13.6%和14.4%,当掺杂纳米粒子质量分数为3wt%时,复合材料击穿场强出现最大值,其中纳米ZnO/LDPE复合材料比MMT/LDPE复合材料的击穿场强值高0.68%;电导率试验结果表明：纳米ZnO/LDPE复合材料电导率比MMT/LDPE复合材料低。介电性能测试表明,在1~10⁵ Hz的测试频率范围内,纳米ZnO/LDPE复合材料和MMT/LDPE复合材料介电常数降低,介质损耗角正切值有所提高。     

微纳米SiO_2/低密度聚乙烯复合材料的空间电荷性能

高压直流绝缘材料中空间电荷积聚限制了直流输电的发展。为探讨微米SiO_2、纳米SiO_2、微纳米SiO_2及制备工艺对SiO_2/低密度聚乙烯(LDPE)复合材料空间电荷特性的影响。分别利用SEM、FTIR和DSC等对不同SiO_2/LDPE复合材料的微结构、结晶特性等进行了表征,利用热刺激电流(TSC)法研究其陷阱特性,通过电声脉冲(PEA)法研究其空间电荷特性。结果表明:SiO_2的引入使LDPE的晶粒尺寸减小,结晶度提高;SiO_2/LDPE复合材料的TSC曲线所包络面积增大,微米SiO_2的引入使TSC峰向低温方向偏移,而纳米SiO_2的引入使TSC峰向高温方向移动;SiO_2/LDPE复合材料表现出对空间电荷不同程度的抑制作用。微纳米SiO_2/LDPE复合材料的制备工艺对其性能有一定的影响,以母料形式制备微纳米SiO_2/LDPE复合材料时,其性能与后加入无机颗粒对应的SiO_2/LDPE复合材料更接近。     

Cu/ZnO/LDPE纳米复合材料的离子释放及表面沉积物分析

为了降低含铜宫内节育器(Cu-IUD)引起的出血、疼痛和盆腔炎等副作用,本研究制备了新型的IUD用铜/氧化锌/低密度聚乙烯(Cu/ZnO/LDPE)纳米复合材料.并对复合材料的Cu2+和Zn2+释放行为,以及复合材料的表面特征进行了分析.结果表明,在释放初期阶段,纳米铜和纳米氧化锌含量的增加会抑制对方离子的释放;但在释放后期,则对对方离子的释放不产生显著影响.浸泡后的复合材料表面有大量沉积物,沉积物主要由CuO、Cu2(OH)3Cl、CaNa(H2PO4)3、CaZn(H2PO4)3和Zn4CO3(OH)6·H2O等成分组成.     

纳米ZnO和纳米MMT对低密度聚乙烯介电性能的影响

分别采用添加纳米ZnO和纳米蒙脱土(MMT)粒子的方法提高低密度聚乙烯(LDPE)的介电性能,选择偶联剂对纳米粒子进行表面修饰,并利用熔融共混法制备了纳米ZnO/LDPE和纳米MMT/LDPE复合材料,通过XRD、FTIR和DSC对试样进行表征。研究了复合材料的交流击穿特性,对试样进行了空间电荷试验。结果表明:通过偶联剂修饰,纳米粒子与聚合物之间的界面结合得到改善,且纳米粒子在基体中的分散性更好;同时复合材料的结晶速率提高,结晶结构更完善;添加纳米粒子可以不同程度地提高LDPE的击穿场强,当纳米ZnO和纳米MMT的质量分数均为3wt%时,复合材料的击穿场强达到最大,分别比纯LDPE的击穿场强高出11.0%和10.3%;纳米ZnO和纳米MMT都有抑制空间电荷的作用,且ZnO的抑制效果更明显。     

纳米ZnO/低密度聚乙烯复合材料的介电特性

为探讨纳米ZnO/低密度聚乙烯（LDPE）复合材料的介电特性,首先,采用硅烷偶联剂和钛酸酯偶联剂对纳米ZnO进行改性,并利用两步法制备了不同纳米ZnO质量分数、不同纳米ZnO粒径、不同纳米ZnO表面修饰方式和不同冷却方式的纳米ZnO/LDPE复合材料;然后,通过FTIR、SEM、DSC和热激电流（TSC）测试了纳米ZnO在基体中的分散情况、复合材料的等温结晶过程参数变化及陷阱密度;最后,在不同实验温度下分别进行了交流击穿、绝缘电导率、介电常数和空间电荷实验。结果表明:纳米ZnO的加入使纳米ZnO/LDPE复合材料内部陷阱深度和密度均有所增加;当纳米ZnO的粒径为40 nm且质量分数为3%时,复合材料的结晶速度最快,纳米ZnO在基体中的分散性较好,击穿场强达到最高值133.3 kV/mm,电导率及介电常数也相对较低,加压时复合材料内部空间电荷少,短路时释放电荷速度快,介电性能较好;由于纳米粒子增加了材料内部的热传导速率,降低了复合材料随着温度升高而降解的速度,因而相对于纯LDPE,随着实验温度的提高,纳米ZnO/LDPE复合材料的击穿场强下降幅度及电导率上升幅度均较小。      

ZnO基复合材料的制备及光催化应用研究新进展

介绍了氧化锌(ZnO)基纳米复合材料的制备,包括ZnO与贵金属、石墨烯以及其他半导体材料的复合,调研了ZnO基不同复合纳米材料的光、电以及气敏等特性,综述了ZnO基纳米复合材料光催化性能研究的最新进展,并提出了展望。     

TiO_2/ZnO/凹土复合材料的制备表征及紫外线屏蔽性能的研究

利用纳米二氧化钛(TiO_2)和纳米氧化锌(ZnO)屏蔽不同波长紫外线的各自特性,通过在凹土(ATP)表面负载TiO_2和ZnO来获得高效紫外线屏蔽材料,同时减少TiO_2和ZnO的团聚。并通过XRD、TEM、HRTEM、TG/DSC和Lamda 950UV-Vis等测试手段对所制备的TiO_2/ZnO/ATP复合材料进行表征。研究了煅烧温度对复合材料紫外屏蔽性能的影响。结果表明:TiO_2和ZnO均匀的负载在ATP表面;当煅烧温度为500℃时,所得的TiO_2/ZnO/ATP复合材料具有优异的中、长波广谱紫外屏蔽性能。     

Field emission from zinc oxide nanotowers: the role of the top morphology

Arrays of novel nanometer-scale tower-shaped structures of zinc oxide (ZnO nanotowers) were synthesized by a simple thermal evaporation method. Due to the difference in fabrication conditions, ZnO nanotowers with similar body structure but different top morphologies were obtained. These ZnO nanotowers with different top morphologies showed obvious disparity in field emission, despite their overall field enhancement factor and density being the same. The nanotowers with the sharpest top had the lowest turn-on and threshold electric field. This disparity is attributed to the different local field enhancement factors at the nanotower tops, which were calculated both from the field emission data and by simulation. The above results have demonstrated the essential importance of the top morphology of a ZnO nanostructure in field emission.     

感应耦合辅助磁控溅射氧化锌薄膜在铜铟硒薄膜太阳能电池中的界面(英文)

薄膜铜铟硒太阳能电池由于前后电极间欧姆接触导致电流损耗,高阻氧化锌层可以消除因表面空洞或表面损坏造成的前后电极短路,这种作用大小取决于氧化锌薄膜表面形貌和电阻率.本论文研究了用感应耦合等离子辅助磁控溅射氧化锌薄膜在铜铟硒薄膜太阳能电池中的应用,并分析氧化锌薄膜层和铜铟硒层的界面结构特点.实验用氧化锌陶瓷靶在氧气和氩气环境下进行溅射,当溅射气压为4mTorr,射频功率300W,直流偏压30V时,制备的氧化锌具有表面形貌均匀致密,电阻率为7×108Ω·cm、透光率80%以上等特性,与吸收层铜铟硒构成良好的异质结界面.     

Electron field emission characteristics of different surface morphologies of ZnO nanostructures coated on carbon nanotubes

The optimal carbon nanotube (CNT) bundles with a hexagonal arrangement were synthesized using thermal chemical vapor deposition (TCVD). To enhance the electron field emission characteristics of the pristine CNTs, the zinc oxide (ZnO) nanostructures coated on CNT bundles using another TCVD technique. Transmission electron microscopy (TEM) images showed that the ZnO nanostructures were grown onto the CNT surface uniformly, and the surface morphology of ZnO nanostructures varied with the distance between the CNT bundle and the zinc acetate. The results of field emissions showed that the ZnO nanostructures grown onto the CNTs could improve the electron field emission characteristics. The enhancement of field emission characteristics was attributed to the increase of emission sites formed by the nanostructures of ZnO grown onto the CNT surface, and each ZnO nanostructure could be regarded as an individual field emission site. In addition, ZnO-coated CNT bundles exhibited a good emission uniformity and stable current density. These results demonstrated that ZnO-coated CNTs is a promising field emitter material.     

低温剥离法制备高性能石墨烯/ZnO复合材料

采用氧化石墨和七水合硫酸锌作为初始反应物, 在低温下(80℃)合成了氧化石墨/ZnO, 然后通过低温剥离法制备了高质量石墨烯/ZnO (GNS/ZnO)复合材料. 采用X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱、热重分析仪(TG)、X射线光电子能谱(XPS)、拉曼光谱(RS)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等分析手段对石墨烯/ZnO样品进行了表征. 结果表明: 氧化石墨还原彻底, 纳米ZnO成功地负载到了石墨烯上, 有效地减少了石墨烯片层间的团聚现象. 通过对ZnO和石墨烯/ZnO荧光性能测试, 结果表明: 石墨烯/ZnO发生了荧光淬灭现象, 在光电子领域拥有广阔的应用前景.     

Finite element simulation and experimental research on ZnO:Al by magnetron sputtering

Aluminum doped zinc oxide (ZnO:Al) thin films are suitable for the use as transparent conductive electrode in copper indium gallium selenide Cu(In,Ga)Se₂ thin film solar cells. The resistivity and film quality of ZnO:Al deposited on soda lime glass is nonuniform in magnetron sputtering process. According to the measurement results of magnetic field on the top of the target, obvious magnetic field distribution nonuniformity is observed along the vertical and horizontal directions respectively. With the longer distance between target and substrate, the magnetic field intensity becomes lower and flatter between the two magnet poles. Based on the simulation results by finite element analysis, it is verified the nonuniformity of magnetic field distribution influences the probability of Ar⁺ particles collision and the deposition of zinc oxide (ZnO) particles in different regions on substrate. The higher resistivity of ZnO:Al films is obtained where the magnetic field intensity is stronger.     

Synthesis of ZnO/Ti2C composites by electrostatic self-assembly for the photocatalytic degradation of methylene blue

Journal of Materials Science - Two-dimensional (2D) zinc oxide (ZnO) has great potential in the field of dye photocatalytic degradation. However, the photocatalytic activity is always...     

Modulation of field emission properties of znO nanorods during arc discharge

Zinc oxide (ZnO) nanorods have been synthesized via the arc discharge method. Different oxygen partial pressures were applied in the arc discharge chamber to modulate the field emission properties of the as-synthesized ZnO nanorods. Scanning electron microscopy (SEM) was carried out to analyze the morphology of the ZnO nanorods. The ion beam analysis technique of proton induced X-ray emission (PIXE) was performed to probe the impurities in ZnO nanorods. SEM images clearly revealed the formation of randomly oriented ZnO nanorods with diameters between 10-50 nm. It was found that the morphology and the electrical properties of the ZnO nanorods were dependent on the oxygen partial pressure during arc discharge. In addition enhanced UV-sensitive photoconductivity was found for ZnO nanorods synthesized at high oxygen partial pressure during arc discharge. The field emission properties of the nanorods were studied. The turn-on field, which is defined at a current density of 10 microA cm(-2), was about 3 V microm(-1) for ZnO nanorods synthesized at 99% oxygen partial pressure during arc discharge. The turn-on field for ZnO nanorods increased with the decrease of oxygen partial pressure during arc discharge. The simplicity of the synthesis route coupled with the modulation of field emission properties due to the arc discharge method make the ZnO nanorods a promising candidate for a low cost and compact cold cathode material.     

Effect of MWCNTs/ZnO inorganic fillers on the electrical,mechanical and thermal properties of SiR-based composites

Rubber insulation materials were widely used in the fields of electrical and electronic engineering, especially, which have excellent nonlinear electrical conductivity and can be employed to homogenize the electric field distribution of cable accessories. To enable the rubber materials, such as silicon rubber (SiR), to possess excellent nonlinear electrical conductivity has been a hot issue. In this paper, MWCNTs/ZnO inorganic fillers were prepared by mixing a small amount of multi-wall carbon nanotubes (MWCNTs) with zinc oxide (ZnO) nanosheets, and MWCNTs/ZnO/SiR composites were prepared. The macroscopical properties results show that the nonlinear electrical conductivity characteristics can be induced by filling appropriate content of MWCNTs/ZnO fillers, and the threshold field strength corresponding to the nonlinear conductivity gradually decreases with the increase of MWCNTs filling content, which further decreases with the increase of measured temperature. The COMSOL simulation results also verify that MWCNTs/ZnO/SiR composite with nonlinear conductivity can effectively reduce the electric field strength at the stress cone of cable accessories. In addition, the thermal conductivity and tensile strength for MWCNTs/ZnO/SiR composite are also improved comparing to pristine SiR. This work demonstrates MWCNTs/ZnO/SiR composites possess outstanding overall properties and have good potential to be used in the cable accessory.

     

纳米氧化锌晶体的分区生长

以ZnO粉和石墨粉为原料,用碳热还原法获得了分区生长的多种形貌ZnO晶体.采用XRD、FESEM、HRTEM、EDS和PL谱等测试手段分别对产物进行了分析表征.结果表明:所得产物均为六方纤锌矿ZnO晶体,但具有不同的晶体形态特征.浅黄色产物主要为四足和两足状ZnO晶须,白色产物为单一片状ZnO晶体.同时初步分析和讨论了产物分区生长的原因和生长机理.     

Field emission characteristics from tapered ZnO nanostructures grown onto vertically aligned carbon nanotubes

Zinc oxide (ZnO) nanostructures were grown on vertically aligned carbon nanotubes (CNTs) using thermal chemical vapor deposition (CVD) to enhance the field emission characteristics. The shape of ZnO nanostructure was tapered. Scanning electron microscopy (SEM) image showed the ZnO nanostructures were grown onto CNT surface uniformly. The field electron emission of pristine CNTs and ZnO-coated CNTs were measured. The results showed that ZnO nanostructures grown onto CNTs could improve the field emission characteristics. The ZnO-coated CNTs had a threshold electric field at about 3.1 V/μm at 1.0 mA/cm². The results demonstrated that the ZnO-coated CNT is an ideal field emitter candidate material. The stability of the field emission current was also tested.