通过热氧化Cu制备CuO纳米线

通过在空气中热氧化Cu片制备CuO纳米线,研究了不同氧化温度对CuO纳米线形貌的影响.利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)分析不同温度下CuO纳米线的结构、形貌,结果表明氧化温度对CuO纳米线的直径和长度有较大的影响,在600℃的条件下获得的CuO纳米线直径为140 nm、长度为4μm,600℃为CuO纳米线的最佳的生长温度.用扫描电子显微镜(SEM)和能量色散X射线光谱仪(EDX)分析样品的横截面,得到氧化产物呈层状分布,分别为CuO纳米线、CuO层、Cu2O层.     

基于ZnO/Graphene纳米复合材料紫外光探测器的制备与实现

利用化学气相沉积法制备氧化锌（ZnO）纳米线,通过微加工工艺获得了基于 ZnO 纳米线与ZnO石墨烯量子点纳米复合材料的紫外光探测器。ZnO 石墨烯纳米复合材料的结构和表面形貌通过 X 射线电子衍射和扫描电镜来表征,结果表明,ZnO 纳米线的直径约为33 nm,与石墨烯量子点很好地复合在了一起。利用紫外可见吸收谱对样品的光吸收进行了记录,实验表明,基于ZnO复合石墨烯量子点纳米复合材料的紫外探测器在 UV 照射下显示出良好的光响应行为,该类型基于ZnO复合石墨烯量子点探测器可能在ZnO紫外探测的应用方面具有潜在的意义。     

ZnO纳米线的掺杂及特性研究进展

ZnO纳米线以其独特的磁性和光电性能在许多领域获得了广泛的应用。ZnO纳米线的掺杂改性是充分发挥其形貌和功能特性的有效途径。阐述了掺杂ZnO纳米线常用的制备方法及研究状况,介绍了掺杂改性对ZnO纳米线的磁性能、气敏性和光学性能的影响。最后总结了目前掺杂改性研究中尚待解决的问题,并对其发展趋势及前景进行了展望。     

用纳米原料制备SrM永磁铁氧体研究

分别采用纳米和微米原料(SrCO3、Fe2O3)进行高温固相反应,制备了SrM磁块.结果表明,当预烧温度为1000℃时,纳米原料样品为单一的M相,所需的预烧温度比微米级原材料的预烧温度低150℃左右.当预烧温度为1200℃时,预烧样品晶粒生长均匀,粒度分布理想.当烧结温度为1150℃,生成的SrM综合磁性能最佳,剩磁为...     

纳米氧化锌/聚乙烯复合材料中空间电荷及体积电阻率的研究

以溶融共混法制备了纳米氧化锌(ZnO)/低密度聚乙烯(LDPE)的复合材料,采用电声脉冲法和高阻计法分别测量了不同纳米ZnO含量试样中的空间电荷分布和体积电阻率。实验发现,试样中的空间电荷分布明显不同于纯聚乙烯。当试样中纳米ZnO含量为0.5%时,短路过程中空间电荷衰减很快;当纳米ZnO含量进一步提高时短路过程中空间电荷衰减比纯聚乙烯的缓慢。同时发现加入纳米ZnO后复合材料的体积电阻率上升。讨论了纳米ZnO对试样中空间电荷形成和导电机理的影响。     

化学共沉法制备的高饱和磁化强度Fe65Co35合金纳米颗粒

利用化学共沉淀法制备Fe65Co35合金纳米颗粒,研究了共沉淀和退火工艺对纳米颗粒结构和磁性能的影响.研究表明,共沉淀反应的油浴温度为100℃时,最有利于FeCo合金的生成.在此油浴温度下合成的产物经300℃退火获得的磁性颗粒尺寸均匀、细小且磁性能最佳.低于或高于此油浴温度对产物的形貌和性能均产生不利的影响.随退火温度...     

工艺参数对Fe-3Si-0.5Al-2Ni-2Ti磁粉心性能的影响

采用气雾化制粉和模压成型方法制备了Fe-3Si-0.5Al-2Ni-2Ti磁粉心,通过扫描电镜、X射线衍射仪以及软磁交流测量装置观察并表征了软磁合金粉末的形貌、相结构以及磁粉心的磁特性,探讨了粉末粒度、绝缘剂添加量、退火温度对磁粉心的有效磁导率μe·功耗Pcv的影响.结果表明,随着粉末粒度的减小,磁粉心的有效磁导率μe、功耗Pcv降低;随着绝缘剂含量的增加,有效磁导率μe、功耗Pcv降低;随着退火温度的变化,磁粉心有效磁导率μe及功耗Pcv在不同的温度阶段表现出不同的变化规律,当温度由180℃升至280℃,磁粉心μe缓慢升高,而功耗Pcv则明显降低;当温度进一步升至380℃,磁粉心有效磁导率μe出现大幅降低,而功耗Pcv则急剧升高.     

微波辅助polyol法制备的纳米镍颗粒

采用微波辅助polyol还原法制备了单分散的纳米Ni颗粒。分别用X射线衍射(XRD)和透射电镜(TEM)观测样品的相结构和微观形貌,用振动样品磁强计(VSM)测试Ni颗粒的磁性。XRD显示样品为面心立方结构,TEM观察显示金属镍颗粒的形貌是理想的球型。当把反应温度提高到400℃,并且在实验过程中加入适量的PVP时,发现镍颗粒呈现出一种毛茸茸的多毛形态,这种分散均匀的单一态形貌类似于纳米头发的结构。同时,VSM测试结果表明球型纳米Ni颗粒具有典型的铁磁性。     

不均匀电场下纳米氧化锌改性环氧树脂的绝缘特性

为研究纳米ZnO掺杂对环氧树脂复合材料绝缘特性的影响,以纳米ZnO改性双酚A型环氧树脂材料为研究对象,考察了不同掺杂量下复合材料直流电导、介电常数等绝缘特征参数的变化趋势;并利用针板电极系统,分别对ZnO/环氧和SiO_2/环氧复合材料进行了起始局放电压对比测试。研究发现,当纳米ZnO质量分数15%时,复合材料开始呈现非线性电导特性,复合材料介电常数也发生显著变化,质量分数为30%时其电导非线性系数可达到18.7,介电常数则可上升至5.9。相同电极结构下,纳米ZnO/环氧复合材料的起始局放电压显著高于SiO_2/环氧复合材料,ZnO质量分数为15%时起始局放起始电压达到最大值,分别比无掺杂树脂及纳米SiO_2掺杂树脂提高了33%和22%。研究表明,纳米ZnO粒子的引入显著提高了环氧树脂复合材料的绝缘性能,纳米ZnO粒子的界面效应和非线性电导特性在改善复合树脂绝缘特性方面发挥了主要作用。     

不同波长光激发下氧化锌纳米线的发光特性研究

用汽相传输法制备了氧化锌(ZnO)纳米线,并在室温条件下,测量了在不同波长光的激发下,样品的光致发光谱.实验结果表明,当用325 nm的光激发ZnO纳米线时,观察到峰值波长约为392 nm的紫光峰峰值强度强,峰值波长约为445 nm的蓝光峰峰值强度较弱和峰值波长约为486 nm的蓝绿光峰峰值强度弱;当增加激发光波长到380 nm时,发射光谱变成峰值波长约为520 nm的半高宽较宽、峰值强度较强的带状光谱.同时对发光峰产生的机理进行了分析.     

Synthesis,Optical Characterization and Growth Mechanism of Centimeter Long ZnO Nanocombs

ZnO nanocombs were successfully synthesized by thermal evaporation with the catalyst of CuO. The lengths of these ZnO nanocombs range from several millimeters to more than one centimeter. It was demonstrated that the quantities and quality of the nanostructures were affected by the reaction source and the growth temperature. The appearance of Cu₂O (220) diffraction peak coincided with previous TEM results, which indicated that the CuO powder did involve in the growth process. Wedge interfere experiment revealed that the thickness along the comb branch growth direction was different, while the thickness along the ribbon was the same. In the end, a possible growth mechanism of ZnO nanocombs was proposed.     

Tailoring the structural and optical properties of RF magnetron sputtered ZnO/graphene thin films by annealing temperature

Abstract

ZnO and ZnO/Graphene thin films were deposited on Cu substrate using a low pressure chemical vapor deposition (LPCVD) and the magnetron sputtering method. The impacts of graphene layer growth and annealing temperature on the optical properties ZnO and ZnO/Graphene thin films were investigated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), X-ray photoelectron spectroscopic (XPS), and photoluminescence (PL) measurements respectively. XRD and SEM results reveal that all the thin films preferred the crystalline [001] orientation along the c-axis direction, which were vertical grown on substrate surface. By comparing the results and analysis of their structure, morphology, chemical bonding and optical property, it is proved that using Graphene as a buffer layer can improve the crystal quality of ZnO thin films. For the annealed ZnO/graphene nanostructures, the area ratio of UV and visible emission region of ZnO/graphene thin films increase with increasing the annealing temperature, reaches a maximum at 500?°C and then starts decreasing with further increase in annealing temperature, which indicating that the controllable ZnO/Graphene thin films have the higher crystallization quality at the annealing temperature of 500?°C. Our results demonstrate that for high quality ZnO/graphene thin films deposition, decreasing the defect concentration should be preferable to simply applying the proper annealing temperature, which might have promising applications for various UV photodetectors devices.     

Synthesis of Zinc Oxide Nanowire-Nanowall-Like Hybrid Structures on Graphene

ZnO nanowire-nanowall-like hybrid structure on graphene was synthesized with a simple chemical vapor deposition technique. This was done without a template by utilizing a catalyst to control the growth time and condensation. The surface morphology of nanostructure was characterized by using a field emission scanning electron microscope (FE-SEM). We found that the ZnO nanowire-nanowall-like hybrid structure was uniformly deposited on the graphene. The extremely strong ZnO (0002) peaks were observed by using x-ray diffraction (XRD). This method showed the preferred (0001) orientation and high crystalline quality of the ZnO nanostructures. The optical properties were investigated utilizing photoluminescence (PL). These results showed the strong green-yellow emission attributed to the robust inner reflection and scattering. This simplified method has great potential in synthesizing uniform ZnO nanowire-nanowall-like hybrid structures on graphene. These nanostructures may have important applications in new types of flexible gas sensors or other fields demanding high surface area materials.     

Al掺杂的ZnO纳米结构材料制备及其电极设计

介绍了一维Al掺杂的ZnO（Al-ZnO）纳米结构材料的制备,研究了该材料体系的电极设计与优化。结果表明,适合于这种材料的电极为Au／Ni双层金属膜,经过在Ar和N2气氛中分别退火处理后,Au／Ni双层金属膜与Al-ZnO纳米结构材料的接触电阻得到明显降低,并且在Ar气氛中退火要好于在N2气氛中退火。     

Recent developments in tight-binding approaches for nanowires

Full-band nanowire simulations pose significant computational challenges. Nanowires and nanostructures in general have many interfaces, may be composed of alloys, and feature confinement on a scale of a few tens of nanometers. The empirical tight-binding approach is well-suited for modeling these devices: Its basis consists of atomic-like orbitals with limited-range interactions and reasonably-sized basis sets can accurately reproduce the bands of a wide range of semiconductors. The method easily accommodates strain and electromagnetic fields. Over the years the application of the tight-binding approach to nanodevices such as superlattices and resonant-tunneling diodes has led to the development of many useful computational techniques. Recently, its application to random-alloy nanowire calculations has led to the development of approximate bandstructure methods superior to the Virtual-Crystal Approximation for these nanostructures, and its use in nanowire transmission calculations has led to a highly efficient method for transmission calculations. I discuss tight-binding models generally and then give a more in-depth discussion of the recent developments in tight-binding models as applied to nanowires.     

单束飞秒激光诱导ZnO晶体表面纳米周期结构的形成

介绍了不同波长的飞秒激光脉冲诱导ZnO晶体表面纳米周期结构,分析了纳米结构的周期Λ与激光波长λ的关系。结果表明:纳米结构的周期与材料折射率n有关,其与激光波长成线性,且符合Λ=λ/2n的关系。提出了样品分层的模型,解释了飞秒激光诱导纳米周期结构的形成机理。     

Effect of Liquid Phase and Vaporization on the Formation of Microstructure of Pr Doped ZnO Varistor

Our previous works and our recent data were summarized to discuss the effect of liquid phase formation and vaporization of the components on the densification, grain growth and change of the microstructure of Pr doped ZnO ceramics in air. In the ZnO-Pr₂O₃ binary system, eutectic liquid forms at 1382± 5°C° and significant vaporization of the components occurred above the eutectic temperature. Below eutectic temperature (1350°C), only 0.1 mol % of Pr doping into ZnO brought about the grain growth of ZnO, however further addition of Pr brought about the suppression of the grain growth. Comparing the grain size distribution at the surface and inside part of Pr doped ZnO ceramics, it was clarified that wider grain size distribution was observed at the surface than inside part. At the temperature just below the eutectic (1370°C), abnormal grain growth was also observed. Depth profile of Pr content indicated that no concentration gradient was observed below eutectic temperature (1350°C), however above eutectic temperature (1500°C), condensation of Pr was observed at the surface. Grain growth rate as well as weight loss rate were drastically increased between 1350 and 1370°C, which suggested that formation of liquid phase accelerate the grain growth rate and weight loss rate. Consequently the microstructure of Pr doped ZnO ceramics was formed by both effects on the formation of liquid phase and on the vaporization of the components.     

Effect of temperature on elasticity of P doped silicon nanowires

A semi-continuum approach is developed for mechanical analysis of a Phosphorus (P) doped silicon nanowire. Young's modulus of the silicon (001) nanowire with different size along [100] direction is obtained by the developed semi-continuum approach. The results show that Young's modulus of the P doped silicon nanowire decreases dramatically as the size of the width and thickness scaling down. The approach is extended to perform a mechanical analysis of the silicon nanowire at finite temperature. The dependence of young's modulus of the P doped silicon nanowire on temperature is predicted, and it exhibits a negative temperature coefficient.     

Simulation study of temperature sensitivity of silicon nanowire transistors with different types of orientations

This paper presents the temperature characteristics of a silicon nanowire transistor and its use as a temperature sensor. The OMEN nanowire simulation tool was used to investigate the temperature characteristics of the transistor. Current–voltage characteristics with different values of temperature for three orientations were simulated. The metal–oxide–semiconductor (MOS) diode connection suggests the use of the silicon nanowire transistor as a temperature nanosensor. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Comprehensive modeling of optoelectronic nanostructures

This paper gives an overview of physics-based modeling of optoelectronic nanostructures, driven by diverse applications such as photovoltaics, solid-state lighting, communications and sensing. Despite this broad field of applications, some common challenges can be identified: accurate modeling of light-matter interaction, semi-coherent carrier transport in the presence of strong recombination, calculation of material properties and electromagnetic characteristics. In this contribution, the general purpose simulation framework tdkp/AQUA/LUMI is presented, with the focus on non-planar nanowire devices.