纳米金刚石在惰性气氛下的热处理

本文采用不同分析手段(其中包括TEM、SEM、RS和DSC等)对纳米金刚石粉末在惰性气氛下的25 1200℃热处理效应进行了深入细致的研究。研究发现经过热处理的纳米金刚石粉末在颗粒形貌和结构方面均存在不同程度的变化,Raman光谱和DSC分析还证实了纳米金刚石粉末在约751℃左右经历了石墨化的转变,该相变温度远低于体材料金刚石,原因在于粉末材料的纳米尺度效应。     

Preparation of few-layer graphene-capped boron nanowires and their field emission properties

Large-area boron nanowire(BNW) films were fabricated on the Si(111) substrate by chemical vapor deposition(CVD). The average diameter of the BNWs is about 20 nm, with lengths of 5–10 μm. Then, graphene-capped boron nanowires(GC-BNWs) were obtained by microwave plasma chemical vapor deposition(MPCVD). Characterization by scanning electron microscopy indicates that few-layer graphene covers the surface of the boron nanowires. Field emission measurements of the BNWs and GC-BNW films show that the GC-BNW films have a lower turn-on electric field than the BNW films.     

Towards an optical coupler using fine-wire: a study of the photovoltaic effect of a heterojunction formed in a single fine-wire of tungsten oxides

Nanodevices using the photovoltaic effect of a single nanowire have attracted growing interest. In this paper, we consider potential applications of the photovoltaic effect to optical signal coupling and optical power transmission, and report on the realization of a heterojunction formed between WO₂ and WO₃ in a fine-wire having a diameter on the micrometer scale. Using a laser beam of 514.5~nm as a signal source, the WO₂--WO₃ heterojunction yields a maximum output power of up to 37.4 pico watt per heterojunction. Fast responses (less than a second) of both photovoltaic voltage and current are also observed. In addition, we demonstrate that it is a simple and effective way to adapt a commercial Raman spectrometer for the combined functions of fabrication, material characterization and photovoltaic measurement of an optical signal coupler and optical power transmitter based on a fine-wire. Our results show an attractive perspective of developing nanowire or fine-wire elements for coupling optical signals into and for powering a nanoelectronic or nano-optoelectronic integrated circuit that works under the condition of preventing it from directly electrically connecting with the optical coupler.     

氧化钨纳米线结构相变的拉曼光谱研究

本文利用拉曼光谱技术对氧化钨纳米线结构随激光功率改变而变化的情况进行了研究。研究结果表明氧化钨纳米线在一定功率的激光照射下被氧化成了三氧化钨纳米线;随着激光功率的进一步增大,纳米线温度进一步升高,三氧化钨纳米线由开始的单斜相向正交相结构过渡。实验证实三氧化钨纳米线的相变过程是可逆的,而之前的氧化过程是不可逆的。     

碳纳米管场致电子发射新机制

基于对长达 1μm的 (5 ,5 )碳纳米管的量子力学计算 ,作者发现使碳纳米管具有优异场致电子发射特性的因素除了人们预期的尖端场增强之外 ,电荷在纳米管尖端的积累造成有效功函数 (真空势垒 )的非线性下降也起了非常重要的作用 .对外加电场Vappl=10— 14V/ μm下的碳纳米管进行了计算 ,得到与实验结果相近的发射电流