Atomic interaction and structural stabilities of Mg, Zn on Si surfaces and their alloys

在当今追求科技产品多功能的信息时代，人们对微纳尺度光电器件和电子器件的集成要求日益提高。如何将以Si基半导体为代表的电子结构材料与宽禁带半导体结构材料制备在一起，成为人们关注的科学问题。然而，Si表面上金属原子所形成的结构稳定性和相互作用不确定，MgxZn1－xO混晶中相结构稳定性和原子相互作用等问题，极大地制约了这些半导体结构材料的应用。为此，本论文着重就Si(111)-(7×7)表面Mg/Zn结构和MgxZn1－xO混晶相结构的稳定性及其原子间相互作用开展研究。 首先，使用扫描隧道显微镜，在室温下对Mg在Si(111)-7×7表面上的初期吸附过程进行了表征，根据STM图中亮点数目的不同，...In the present information age, the integration of micro/nano optoelectronic and electronic devices has attracted much more attention to pursue the multi-functions products. How to integrally prepare typical electronic Si-based structure semiconductors with wide band gap semiconductors becomes a current topic. However, the structural stability and the interaction of relevant atoms will greatly res...学位：理学博士院系专业：物理与机电工程学院物理学系_凝聚态物理学号：1982006015317

基于有限元模拟与数值计算的微电磁继电器结构设计与性质研究

运用ANSYS有限元模拟、Mathematica数值计算与OriginPro8.6图像处理等软件对多重弯曲的平面磁芯线圈电磁场分布以及活动电极在电磁场中所受电磁力情况进行仿真分析,从而合理设计励磁电流、活动电极材料、结构尺度、活动电极与固定电极的位置间距等.国家自然科学基金面上项目(No.61674124);;厦门大学校长基金项目(No.20720160122

微电磁光开关的结构设计与性质模拟

基于微电磁光开关的工作原理,设计了MEMS电磁反射型光开关.采用ANSYS 9.0有限元软件分析结合Mathematica数值计算研究了微电磁光开关所需的电磁力、磁芯线圈的磁场分布、悬臂梁受电磁力的形变状态,从而获得磁芯线圈的匝数、悬臂梁位置、悬臂梁与平面磁芯线圈接触区域等结构参量.九江市杰出青年基金项目(No.2018042)厦门大学校长基金项目(No.20720190055

Electrochemical Performance of Screen-Printed Composite Coatings of Conducting Polymers and Carbon Nanotubes on Titanium Bipolar Plates in Aqueous Asymmetrical Supercapacitors

用导电聚合物（聚吡硌、聚苯胺）与碳纳米管（经酸处理）复合物（ECP-CNT）以及功能添加剂（表面活性剂：苄索氯铵 benzethonium chloride，粘结剂：聚乙烯醇 polyvinyl alcohol）配成水型印泥（aqueous ink)，在钛片（厚度：0.1 mm）上网印（screen printing）成所需载量及面积（例如：75 mg cm-2，100 cm2）的均匀的ECP-CNT膜. 以该膜为正极，网印活性炭（pigment black）膜为负极，3.0 mol L-1 KCl 或 1.0 mol L-1 HCl 为电解质，组装不对称超级电容器. 用循环伏安、恒电流充放电、电化学阻抗、光及电显微等方法研究了ECP-CNT复合物、网印膜、单池以及由双极片（bipolar plate）连接的多池堆（multi-cell stack）. 以两片印刷面积为100 cm2 的钛双极片组装成三池堆，得到较好的技术指标：堆电压3.0 V，电极电容1.29~1.83 F cm-2，比能量2.30~3.24 Wh kg-1，最大比功率1.04 kW kg-1.Composites of conducting polymers (polypyrrole and polyaniline) with acid treated multi-walled carbon nanotubes were formulated into printable aqueous inks, with the aid of functional additives (benzethonium chloride as a surfactant with or without polyvinyl alcohol as a binder). The inks were screen-printed as fairly uniform coatings of various mass loading densities and areas (up to 75 mg cm-2 and 100 cm2) on thin titanium plates (0.1 mm in thickness). These screen-printed plates were used to fabricate both unit cell and multi-cell stack of asymmetrical supercapacitors with screen-printed negative electrodes of activated carbon (pigment black) in aqueous electrolytes (3.0 mol L-1 KCl or 1.0 mol L-1 HCl). In particular, a three-cell stack with two bipolar Ti plates of 100 cm2 in screen-printed area was constructed, demonstrating promising technical specifications: 3.0 V in stack voltage, 1.29~1.83 F cm-2 in electrode capacitance, 2.30~3.24 Wh kg-1 in specific energy, and 1.04 kW kg-1 in maximum specific power. Cyclic voltammetry, galvanostatic charging and discharging, and electrochemical impedance spectrometry were applied to study the composites, screen-printed coatings and individual and bipolarly stacked cells, assisted by optical and electron microscopy.The authors thank E.ON AG for funding through the E.ON International Research Initiative-Energy Storage 2007.The authors thank E.ON AG for funding through the E.ON International Research Initiative-Energy Storage 2007.作者联系地址：诺丁汉大学 工程学部化学工程和环境工程系及能源与可持续性研究所，英国 诺丁汉 NG7 2RDAuthor's Address: Department of Chemical and Environmental Engineering, and Energy and Sustainability Research Division, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK通讯作者E-mail：[email protected]

Phase Segregation of ZnO/ZnMgO Superlattice Affected by Ⅱ-Ⅵ Ratio

在zn1-X Mg X O中,X=0.4~0.6仍为一个岩盐矿和纤锌矿共存的结构,影响了其晶格质量。本文利用等离子体辅助的分子束外延设备在C面蓝宝石衬底上外延生长了znO/znMgO超晶格,并改变其生长过程中的Ⅱ-Ⅵ比,利用原子力显微镜、X射线衍射、透射谱和X射线光电子能谱对样品进行了表征分析。发现在较低氧分压下制备的样品结构以岩盐矿为主导,而在较高氧分压下两相共存并以纤锌矿为主。这种相分离现象与裂解氧原子的密度有关。ZnMgO alloy allows for tunable optoelectronic devices.However,the compositional range between ZnO and MgO is interrupted by a crystalline miscibility gap where the wurtzite crystal structure of ZnO is structurally incompatible with the rocksalt structure of MgO.In this article,ten periods of ZnO / ZnMgO superlattice were produced by plasma-assistant molecular beam epitaxy on cplane sapphire substrate with different oxygen condition.It is found that the sample grown at lower oxygen flow and radio-frenquency( RF) plasma power tends to form rocksalt phase.With the increase of oxygen flow and RF plasma power,wurtzite phase tends to dominate and phase segregation is enhanced.The phase transform affected by the oxygen atoms density is reasoned by the formation enthalpies of ZnO and MgO.国家自然科学基金(61076084)资助项

Tailoring of polar and nonpolar ZnO planes on MgO (001) substrates through molecular beam epitaxy

Polar and nonpolar ZnO thin films were deposited on MgO (001) substrates under different deposition parameters using oxygen plasma-assisted molecular beam epitaxy (MBE). The orientations of ZnO thin films were investigated by in situ reflection high-energy electron diffraction and ex situ X-ray diffraction (XRD). The film roughness measured by atomic force microscopy evolved as a function of substrate temperature and was correlated with the grain sizes determined by XRD. Synchrotron-based X-ray absorption spectroscopy (XAS) was performed to study the conduction band structures of the ZnO films. The fine structures of the XAS spectra, which were consistent with the results of density functional theory calculation, indicated that the polar and nonpolar ZnO films had different electronic structures. Our work suggests that it is possible to vary ZnO film structures from polar to nonpolar using the MBE growth technique and hence tailoring the electronic structures of the ZnO films

基于内毒素血症探讨皂术茵陈方对非酒精性脂肪性肝炎大鼠的影响

目的 基于内毒素血症探讨皂术茵陈方防治非酒精性脂肪性肝炎(NASH)大鼠的影响及其作用机制。方法 采用随机数字表法将40只大鼠分为5组,即正常组、模型组、皂术茵陈方组、盐酸吡格列酮组及培菲康组,每组8只。除正常组外,其余32只大鼠采用高脂饮食16周建立大鼠NASH模型,在造模第9周开始,皂术茵陈方组给予皂术茵陈方水提液60 mg/(kg·d)灌胃,盐酸吡格列酮组给予盐酸吡格列酮10 mg/(kg·d)灌胃,培菲康组给予培菲康210 mg/(kg·d)灌胃,正常组及模型组均给予双蒸水10 mL/(kg·d)灌胃,共治疗8周。第16周末经腹主动脉取血,生化法检测肝组织甘油三酯(TG)水平,苏木精—伊红(HE)染色观察肝组织病理学变化。终点显色法检测血浆内毒素(LPS)含量。ELISA法检测肝组织肿瘤坏死因子-α(TNF-α)、白细胞介素(IL)-1β、IL-6等炎症因子的表达水平。结果 与正常组比较,模型组大鼠肝组织显示出典型的NASH组织学特征,出现重度脂肪变性,不同程度的炎细胞浸润和坏死灶。大鼠肝湿重、肝指数、肝脏TG含量、血浆LPS水平、肝组织TNF-α、IL-1β、IL-6等炎症因..

The Structure Properties of Mg_xZn_(1-x)O

采用第一性原理计算模拟了不同组分的MgxZn1-xO半导体混晶的晶格常数、总能、结构,以及禁带宽度的变化。计算结果显示,随着Mg组分的增加,晶格常数逐渐减小,晶体逐渐偏离纤锌矿结构。对各种不同的Mg原子排列情况进行比较认为,MgxZn1-xO的结构随组分x的增大,发生从纤锌矿到岩盐矿的结构相变的可能性高于发生相分离。另一方面,禁带宽度随组分增大主要由价带顶的移动所致。进一步分析Mg原子各种电子态对价带的影响表明,Mg对价带顶附近能带的贡献依次来自p、d、s态电子。随着组分x的增加,p态电子在价带顶附近的密度明显提高,说明sp轨道杂化不但对晶体的几何结构产生影响,而且对其电子结构也起重要作用。A first principles calculation is used to simulate the changes of the lattice constant,band gap,total energy and structure of MgZnO semiconductor alloys with the different MgO mole fractions.The calculated results show that the lattice constant diminishes and the crystal structure departures gradually from the wurtzite type as the MgO mole fraction increases.By comparison with the different positions of the Mg atom,it is suggested that the structure of Mg_xZn_ 1-xO alloy will change and the possibility of the phase transition will be higher than that of the phase separation as the MgO mole fraction increases.On the other hand,when the MgO mole fraction is increased,the band gap enlarges,which is mainly attributable to the shift of the top of the valence band away from the Fermi level.By construing the influence of all kinds of electronic states in Mg atom on the valence band,it shows that the contribution of Mg to the energy band near the top of the valence band takes turn from its p,d,s states.The density of the p states near the top of the valence band enhances prominently when the MgO mole fraction is increased.It indicates that the sp hybridization not only affects the structure of the crystal but also plays an important role for its electronic structures.国家自然科学基金(60376015,90206030,60336020,10134030);; 国家“973”计划(001CB610505);; 福建省科技项目(2004H054,E0410007)资助项目~

Optimal Analysis of the Performance of a New Heat-driven Semiconductor Thermoelectric Refrigerator

提出一种新型的热驱动半导体制冷器模型 ,以制冷系数和制冷率为目标函数分析其性能特性。计算在不同情况下热驱动半导体制冷器的最大制冷系数和制冷率。进而优化工作电流的最佳范围 ,从而确定热驱动半导体制冷器的内部结构参数。所得结果可为新型的热驱动半导体制冷器的优化设计和最佳运行提供有价值的理论指导 ,可促进热驱动半导体制冷器的开发和在不同高新科技领域中的应用。The model of a new heat-driven semiconductor thermoelectric refrigerator is put forward. The coefficient of performance and the rate of refrigeration are taken as objective functions and used to analyze the performance characteristics of the refrigerator. The maximum coefficient of performance and the rate of refrigeration of the refrigerator are calculated at different cases. The optimal range of the electric current is optimized. The reasonable values of the internal structure parameter of the refrigerator are determined. The results obtained here may provide some valuable theoretical guidance for the optimal design and the operation of new heat-driven semiconductor refrigerators. This will promote the further exploitation of heat-driven semiconductor refrigerators and their applications in the new different regions of science and technology

OPTIMUM DESIGN OF THE PERFORMANCE PARAMETERS OF A SOLAR-DRIVEN SEMICONDUCTOR THERMOELECTRIC GENERATOR

应用非平衡态热力学理论,研究太阳能驱动半导体温差发电器的性能特性,确定发电器在最大效率时的优化条件,对系统的主要参数作了详细的讨论,得到一些有意义的新结论。The theory of non-equilibrium thermodynamics was used to investigate the characteristics of a solar-driven semiconductor thermoelectric generator.The optimally operating conditions of the generator at the maximum efficiency were determined.The main parameters of the generator were discussed in detail,and consequently,some new significant conclusions were obtained.福建省和厦门市科技重点资助项