多光子纳米加工中激光扫描条件对金属微纳结构的影响

研究了飞秒激光多光子还原制备银微纳结构技术中激光扫描条件对金属微纳结构与形貌的影响。结果表明:增加激光扫描点间距d可获得较小线宽,延长曝光时间t使线条变宽,增加扫描次数N可使金属微纳结构表面银纳米粒子熔融凝固成较大尺寸颗粒及块状物。     

Dye-sensitized solar cells based on ZnO nanotetrapods

In this paper, we reviewed recent systematic studies of using ZnO nanotetrapods for photoanodes of dye-sensitized solar cells (DSSCs) in our group. First, the efficiency of power conversion was obtained by more than 3.27% by changes of conditions of dye loading and film thickness of ZnO nanotetrapod. Short-circuit photocurrent densities (Jsc) increased with the film thickness, Jsc would not be saturation even the film thickness was greater than 35 μm. The photoanode architecture had been charactered by good crystallinity, network forming ability, and limited electron-hopping interjunctions. Next, DSSCs with high efficiency was devised by infiltrating SnO2 nanoparticles into the ZnO nanotetrapods photoanodes. Due to material advantages of both constituents described as above, the composite photoanodes exhibited extremely large roughness factors (RFs), good charge collection, and tunable light scattering properties. By varying the composition of the composite photoanodes, we had achieved an efficiency of 6.31% by striking a balance between high efficiency of charge collection for SnO2 nanoparticles rich films and high light scattering ability for ZnO nanotetrapods rich films. An ultrathin layer of ZnO was found to form spontaneously on the SnO2 nanoparticles, which primarily was responsible for enhancing open-circuit photovoltage (Voc). We also identified that recombination in SnO2/ZnO composite films was mainly determined by ZnO shell condition on SnO2, whereas electron transport was greatly influenced by the morphologies and sizes of ZnO crystalline additives. Finally, we applied the composite photoanodes of SnO2 nanoparticles/ZnO nanotetrapods to flexible DSSCs by low temperature technique of "acetic acid gelation-mechanical press-ammonia activation." The efficiency has been achieved by 4.91% on ITO-coated polyethylenenaphtalate substrate. The formation of a thin ZnO shell on SnO2 nanoparticles, after ammonia activation, was also found to be critical to boosting Voc and to improving inter-particles contacts. Mechanical press, apart from enhancing film durability, also significantly improved charge collection. ZnO nanotetrapods had been demonstrated to be a better additive than ZnO particles for the improvement of charge collection in SnO2/ZnO composite photoanodes regardless of whether they were calcined.     

花状纳米结构ZnS:Cu的制备与光学性质研究

采用水热法合成了具有花状纳米结构的ZnS:Cu粉末.利用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)和荧光光谱仪研究了在不同正硅酸四乙酯(TEOS)含量的条件下制备的样品的物相、形貌与光致发光(PL)性质.测试结果表明:制备的ZnS:Cu样品都具有立方相闪锌矿结构;由于TEOS分子...     

Highly Intensified Surface Enhanced Raman Scattering by Using Monolayer Graphene as the Nanospacer of Metal Film–Metal Nanoparticle Coupling System

It is widely accepted that surface enhanced Raman scattering (SERS) enhancement results from a combination of electromagnetic mechanisms (EM) and chemical mechanisms (CM). Recently, the nanoparticle‐film gap (NFG) system was studied due to its strong local enhancement field. However, there are still some technical limitations in establishing effective and simple ways for reliable and precise control of sub‐nanospacer. In addition, works on designing the nanospacer in NFG system for efficient interaction with target molecules for further improving SERS signals are rather limited. Here, a novel NFG system is proposed by introducing ultrathin monolayer graphene as well‐defined sub‐nanospacer between Ag NPs and Ag film (named G(graphene)‐NFG system). The new G–NFG system offers tremendous near‐field enhancement with one of the highest enhancement ratio of 1700 reported to date. These results show that the single‐layer graphene as a sub‐nanospacer renders the proposed G–NFG system with particularly strong EM enhancement (due to multiple couplings including the NP–NP couplings and NP‐film couplings) and additional CM enhancement in detecting some π‐conjugated molecules to function as a powerful tool in analytical science and the related fields.     

Chemical Processing of Nanostructured Cemented Carbide

Chemical processing is becoming a vital component in the economic development of advanced engineering materials. Our research group on chemical processing has been focussed on the development of process to produce nanophase cemented carbide. It is a much more direct route for making WC/Co than traditional processing methods, and offers the potential for lower cost production of novel materials with homogeneous nanophase microstructures and improved properties. This paper addresses the scientific and technical issues relating to the chemical processing of nanophase WC/Co composite powder and their sintering.     

Hydrothermal Synthesis of Nanostructural LaxBi2-xSeyTe3-y Powders

Nanostructural monophase LaxBi2-xSeyTe3-y alloy was synthesized with a hydrothermal route using BiCl3, LaCl3, selenium and tellurium powders as the precursors, NaOH and disodium ethylenediaminetetraacetiate （EDTA） as the additives. The hydrothermally synthesized powders have a petal-like morphology self-structured by the parallel side-by-side arrangement of the nano-scales. It is found that an alkaline additive is necessary for the synthesis of a monophase Bi2Te3 based alloy.     

Magneto-Optical Study of Diluted Magnetic Semiconductor Nanostructures Prepared by Pulsed Laser Deposition

The CdTe/Cd_1–x Mn _x Te quantum well structures have been grown by pulsed laser deposition. X-ray diffraction analysis demonstrates high structural quality of the deposited layers and nanostructures. In the magnetoabsorption spectra the large Zeeman splitting of exciton peak which is corresponded to the heavy-hole exciton transition in the CdTe quantum well layers is revealed. The Faraday rotation spectra of the superlattices is interpreted in framework of the exciton transition for the Cd_1–x Mn _x Te layers at a higher photon energy. Influence of different factors on behavior of the Zeeman splitting and the Faraday rotation in the studied nanostructures is discussed.     

锂离子电池Cu6Sn5负极的研究进展

综述了锂离子电池Cu6Sn5合金的研究进展。介绍了锡铜合金体系作为锂离子电池负极的优势,并指出其循环性能对比石墨负极仍然不够理想。对此,还概述了目前国内外改进锡铜合金材料循环性能的方法,主要包括实现纳米化、薄膜化以及多孔结构。     

氧化物缓冲层制备Si(111)基GaN纳米线

采用氧化物缓冲层,通过射频磁控溅射系统依次在n型Si(111)衬底上沉积Ga2O3/ZnO(Ga2O3/MgO)薄膜,然后将薄膜于950℃氨化合成GaN纳米结构,氨化时间为15min。采用X射线衍射(XRD)、傅里叶红外吸收谱(FTIR)和高分辨透射电镜(HRTEM)对样品的结构进行了分析,结果显示两种缓冲层下制备的样品均为六方纤锌矿单晶GaN纳米结构,且缓冲层的取向对纳米线的生长方向有很大影响;采用扫描电镜(SEM)对样品的形貌进行了测试,发现纳米线表面光滑,长度可达几十微米,表明采用氧化物缓冲层制备了高质量的GaN线。同时对GaN纳米线的生长机理进行了简单讨论。     

AFM 在纳米结构加工中的应用研究

文中阐述了基于自行研制的原子力显微镜(AFM)的纳米刻蚀加工方法，研究了针尖上的载荷大小和扫描次数对加工深度的影响，利用AFM的微探针在氧化铝(Al2O3)材料表面加工出纳米结构，验证了该加工方法的可行性。实验结果表明基于AFM的纳米刻蚀技术可作为加工纳米器件的重要手段。