Fracture mechanics analysis of delamination in a thermoelectric pn-junction sandwiched by an insulating layer

A fracture mechanics analysis is conducted for a delamination problem of a multilayered thermoelectric material (TEM) that consists of an n-type layer and a p-type layer sandwiched by an insulating layer. A time-varying energy release rate is presented when the n-type layer delaminates from the insulating layer. Effects of the temperature difference across the system and the applied electric current on the energy release rate are identified. The influence of the thickness ratio of the insulating layer to the thermoelectric (TE) layer is also examined. Based on the energy release rate criterion, the critical temperature difference for delamination propagation is obtained. Some useful conclusions are given.     

纳米晶双相稀土永磁合金透射电镜薄膜样品的制备

探讨了纳米晶双相稀土永磁合金在ＰＴＦＥ夹具园片抛光法和在离子薄化技术中的电镜薄膜样品的制备,比较了利用离子薄化和电解双喷加离子薄化技术获得的纳米晶双相稀土永磁合金的透射电分析结果,优化了两种方法制备电镜薄膜样品的实验条件及参数范围。探索出较佳的有竽透电镜观察的纳米双相稀土永磁合金薄膜样品的制备方法。     

纳米材料的室温（湿）固相化学反应合成

在室温下通过(湿)固相化学反应合成了ZnS和CeO2等纳米材料,用XRD和TEM对其物相、晶粒形貌和晶粒大小进行了表征。结果表明,用该方法合成纳米粉体具有产率高,不需要溶剂,反应时间短,室温反应和纳料粒子稳定性好等显著优点。     

平行板-圆柱平板线中的TEM波及其特性阻抗

用保角变换法得出平行板-圆柱平板线TEM波分布的近似解析解.首先通过保角变换将平行板-圆柱平板线的横截面变换为圆同轴线的横截面,求出由静态场在此边界条件下电场的解,再乘以波动因子得到TEM波的电场解,然后根据由麦克斯韦方程所联系的电场与磁场的关系,得到磁场的分布,从而给出平行圆同轴线中TEM波的分布规律,最后由变换函数关系得到平行板-圆柱平板线TEM波的分布规律.通过数学软件MATLAB绘制出TEM波在其横截面上的结构图,并计算出其特性阻抗.研究结论对于计算该传输线的衰减常数、了解其功率容量、考虑功率耦合及设计有关的有源器件均有一定的参考价值.     

Spontaneous Vesicle Formation in Mixed Aqueous Solution of Poly-tailed Cationic and Anionic Surfactants

Spontaneous vesicles from the mixed queous solution of poly-talied cationic surfactant PTA and anionic surfactant AOT are firstly obtained.Vesicle formation and characterizations are demonstrated by negative-staining TEM and dynamic light scattering.A monodisperse vesicle system is obtained with a polydispersity of 0.082.Ultrasonication can promote the vesicle formation,Mechanism of vesicle formation is discussed from the viewpoint of molecular interaction.     

Synthesis, Characterization and Magnetic Property Measurements of Zn1－xMnxO Nanoparticles via Vapour Phase Growth

Nanosized Mn-doped ZnO particles were synthesized using a vapour phase growth method. The x-ray analysis revea/s a wurtzite ZnO structure with small expansion of the lattice constants due to the doping of Mn in ZnO. The TEM analysis shows that the nanoparticles have an average diameter around 37 nm, and energy dispersive spectroscopy detection on single nanoparticle indicates that the manganese concentration is around 3.5at.%. Magnetization measurements under field cooling conditions reveal that the as-grown Mn-doped ZnO nanoparticles show paramagnetic behaviour. This work demonstrates that Mn can be doped into nanosized ZnO structures via vapour phase growth, which represents an important step towards the synthesis of nanosized diluted magnetic semiconductors.     

多形态ZnO纳米粒子的制备及其紫外—可见光吸收性能研究

选用失水山梨醇单油酸酯／反应物水溶液／环己烷制成微乳液等“微反应器”，在其中控制反应，制备出了具有球形及棒状、不规则片状与球形但呈细胞器状排布的纳米氧化锌。用透射电镜（TEM）、动态激光光微射（DLLS）与X－射线衍射对产物的结构、形态、大小与化学成分进行了表征。系统研究了反应体系的组分、配比、反应温度及分散方法等反应条件对“微反应器”与产物形态、大小的影响。探讨了ZnO纳米粒子的稳定性及其原因。并对ZnO纳米粒子的紫外—可见光吸收性能进行了表征。