Mn掺杂ZnO纳米线的制备及其光学性能研究

以Zn(CH_3COO)_2·2H_2O、KOH和MnCO_3为原料,采用水热法制备出ZnO纳米棒和Mn掺杂ZnO纳米线.利用扫描电子显微镜、X射线衍射仪、荧光光谱仪对样品的形貌、结构和光学性质进行了表征和分析.结果表明,制备的两组样品结构均为标准的六方纤锌矿结构,并沿c轴择优生长且均匀分布.纯的ZnO样品在375 nm附近发光性能较弱,在570 nm附近发光性能良好.而Mn掺杂ZnO样品在可见光区发光强度增强,并使紫外衍射峰峰位发生红移,最后讨论了样品的发光机理.     

Cu掺杂ZnO纳米线的制备与性能研究

利用碳热还原法制备了纳米线结构的Cu掺杂ZnO基稀磁半导体.通过X射线衍射分析表明,样品为纯相ZnO纤锌矿结构.扫描电镜结果表明所生长的纳米线直径在50~300 nm之间.磁性测量表明样品在室温下呈现室温铁磁性.     

高度择优取向单晶氧化锌纳米线的制备与发光特性

采用电场辅助电化学沉积法,在室温下成功的在阳极氧化铝模板（AAO）内制备了高度择优取向的硫掺杂ZnO单晶纳米线。用X射线衍射仪（XRD）、隧道电子显微镜（TEM）及选区电子衍射（SAED）对样品的形貌、结构进行分析表明,所得样品是高择优取向的单晶,纳米线,长约几到几十微米,平均直径约70nm。X射线光电子能谱（XPS）进一步证实掺杂硫原子的存在,并分析其生长机制。用荧光光谱仪（PL）分析了样品的发光特性,发现除了典型的ZnO纳米线荧光光谱外,还有紫光和蓝光发光。     

用低温化学气相沉积法大量制备单晶ZnO纳米线及其光致发光研究

在氩气气氛中,利用物理蒸发高纯Zn粉和SiO2纳米粉混合物的方法,控制温度在650℃时,获得了大量的六方相ZnO纳米线,直径约40nm,这和先前报道的制备ZnO纳米线的方法相比,温度降低了大约200℃-300℃.纳米线的生长过程中遵循气-固相生长机制.荧光光谱表明产物具有两个发射带,一个处于紫外波段,另一个处在绿光发射带.     

两步法制备性能优良的ZnO纳米线

利用热蒸发和溶液浸泡两步法制备了性能优良的ZnO纳米线,研究了这些ZnO纳米线的光致发光和场发射特性.与直接采用热蒸发方法生长的ZnO纳米线相比,由该方法得到的ZnO纳米线表现出了更好的紫外发光特性,同时发生5 nm的蓝移,场发射测试表明其开启电场和阈值电场分别达到2.3 V/μm和6.8 V/μm.该方法适用于制备光致发光和场发射性能优良的ZnO纳米线.     

ZnO纳米线膜的可控生长及其量子限域效应研究

针对ZnO半导体低维纳电子/光电子器件中纳米线膜的可控性差及其所导致的特性不稳定问题,利用ZnO纳米籽晶层作为引导层,以实现ZnO纳米线膜的垂直取向生长和尺度分布可控制备,并研究低维量子限域效应对ZnO纳米线膜光电特性的影响机制,利用湿化学法在氧化铟锡导电玻璃上制备ZnO籽晶层,随后利用低温水热法进行ZnO纳米线膜的引导生长,样品的显微结构和物相分析表明,通过调节籽晶热处理温度和生长液浓度能够实现ZnO纳米线直径在10～100nm内可调,籽晶热处理温度对纳米线尺度分布影响尤其显著.室温光致发光(PL)谱测试及分析表明,直径小于20nm的ZnO纳米线薄膜样品的PL谱的近紫外带边发射峰相比于更大直径的纳米线样品发生了明显的蓝移,而且半高宽显著减小.利用量子限域效应理论对PL谱带边发射峰随纳米线的尺度分布发生变化的规律进行了合理分析.     

衬底预处理对p-GaN薄膜上ZnO纳米线阵列生长的影响

为了获得具有较好紫外光发射特性的ZnO纳米线,以p-GaN薄膜为衬底,采用水热法在较低的温度(105℃)下制备出了ZnO纳米线阵列,其中纳米线的直径在100~300nm之间。对p-GaN薄膜进行3种不同的预处理,结果表明,将衬底放入氨水中浸泡有利于生长出致密、均匀、定向排列的ZnO纳米线阵列,这与p-GaN薄膜衬底经氨水浸泡后衬底表面的OH-浓度有关,表明纳米线的密度和尺寸与p-GaN薄膜衬底表面的预处理密切相关。另外,该ZnO纳米线阵列具有较好的紫外发射特性,有望在紫外发光二极管领域获得应用。     

制备参数对ZnO纳米线阵列特性的影响

针对目前水热法制备ZnO纳米线生长机制及成核过程中存在的一些模糊问题,利用水热法制备了一维ZnO纳米线阵列,研究了ZnO纳米线生长过程中反应液浓度、生长时间、反应压力、退火条件等实验参数对ZnO纳米线阵列的形貌、微结构及光电特性的影响,讨论了纳米线生长的成核机制及生长机理.研究结果对制备高质量一维ZnO半导体纳米线阵列并将其应用于微纳及光电子器件领域都有一定的参考价值.     

取向ZnO纳米线阵列的生长机理及发光特性

用化学气相沉积法制备了圾向纳米氧化锌（ZnO）阵列；用扫描电镜（SEM）和透射电镜（TEM）观察了制备的纳米ZnO的形貌结构;用荧光光谱仪（PL）分析了样品的发光特性；以气-液-固（VLS）生长模型和Ehrlich-Schwoebel势垒理论解释讨论了ZnO纳米线的生长结构与机理。     

ZnO纳米线阵列/PVK光电二极管制备与特性

采用水热方法在氧化铟锡(ITO)涂覆的玻璃基底上生长出良好取向排列的氧化锌(ZnO)纳米线阵列,采用场发射扫描电子显微镜(FESEM)、X射线衍射仪(XRD)分别测试ZnO纳米线阵列的形貌和晶相结构。测试结果表明:在基底上形成致密、良好取向排列的ZnO纳米线阵列,纳米线的直径为40~50 nm,长度在200~300 nm,具有六方纤锌矿结构。进一步与p型聚乙烯咔唑(PVK)混合,形成p-n异质结器件,研究该器件在暗态和光照下的电流密度-电压(J-V)特性。结果显示:该器件为光电二极管,在暗态和光照下的整流率分别为216和110。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that