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  • [会议] 拓扑型晶粒长大速率方程的评估

    本研究使用系列截面法重建三维纯铁晶粒,并测量了477个完整晶粒的体积V,平均宽度L,切直径C,棱长e,面数f和相邻晶粒平均面数mf。利用MacPherson-Srolovitz方程,我们计算出每个晶粒的长大速率,并利用实验结果评估现存的拓扑型晶粒长大速率方程。结果显示:Mullins和Hilgenfeldt方程在描述晶粒长大时均出现一定误差。此外实验表明,晶粒长大速率[f-m(f)]之间存在线性规律。

  • [会议] 复合光子晶体编码微球的制备及应用

    通过优化制备水相量子点的条件,得到以巯基丙酸为稳定剂的不同颜色水相CdTe量子点(QD);通过对无皂乳液法制备条件的改进,得到不同粒径的单分散性聚苯乙烯纳米粒子;将不同颜色的量子点溶胀到不同粒径的单分散的聚苯乙烯纳米粒子当中,将溶胀有量子点的聚苯乙烯纳米粒子通过微流控装置自组装成的大小可控、尺寸均一的复合光子晶体编码微球(PCB)。这种新型的多功能编

  • [会议] 氢化锂的晶格动力学同位素效应

    本研究内容主要通过第一性原理计算,以混合氢同位素型氢化锂为研究对象,详细研究了氢化锂的晶格动力学同位素效应,以及氢同位素对氢化锂的热力学性质的影响。研究结果表明:与纯的LiH、LiD和LiT只有一种振动模式不同,当晶格中同时存在两种氢同位素时,晶格中的振动模式发生了明显变化,不仅存在氢原子与锂原子之间的振动,且在较高频率(700~800 cm~(-1))处还存在氢同位素原子之间的振动,并且由于氢同位素之间的振动方向的差别,增加了同锂原子之间的振动模式。与此相应,纯的LiH、LiD和LiT不具备拉曼活性,而当两种或两种以上氢同位素在晶格中的同时存在时,氢化锂晶体具有了拉曼活性。通过对比LiD,LiT和LiD_(0.5)T_(0.5)的声子谱发现,随着氢同位素原子质量的增加,光学支的频率显著降低,而对声学支的频率影响相对较弱,只在G-L和L-X方向显著下降。与LiD和LiT相比,LiD_(0.5)T_(0.5)的声子谱中,在G-L和G-K方向声学支的简并作用明显降低,声子态密度的分布更加连续。氢同位素对氢化锂的热力学性质也有明显的影响,随着氢同位素质量的增加,氢化锂的Cv和△S增加,△G和△F降低,Debye温度在高温段显著降低,而在低温区域显著升高。

  • [会议] Large PCBM Crystals Grown by Solvent-Vapor Annealing

    We propose the solvent-vapor annealing (SVA) as an efficient method for the formation of large [6,6]-phenyl C61 butyric acid methyl (PCBM) single crystals. We compared the results in different conditions by changing the organic solvent of SVA and the substrates, showing that we can change the morphology of PCBM crystals by tuning the parameters of the annealing solvent. Then highly ordered hexagonal PCBM crystals with the size more than 150 μm were obtained when the crystallization performed on bare SiO 2 substrate under the saturated vapor of chloroform for annealing. Meanwhile, for further understanding of the method, we propose a crystallization mechanism of the PCBM crystals formation during SVA. Furthermore, our method was applied to a bi-component system, leading to the formation of PCBM and dioctylbenzothienobenzothiophene single crystals. A potential application of this vertical separation of two organic crystals is, such as, OLEDs with separated p-type and n-type layer.

  • [会议] 有色冰洲石晶体热处理褪色及其光学性质的研究

    冰洲石晶体是制作棱镜偏光器件的贵重材料,在偏光技术应用的各个领域发挥着重要的作用。目前,由于冰洲石的来源主要靠天然产出,替代品并不能完全代替冰洲石,人工合成技术尚未达到工业应用标准等原因造成了冰洲石晶体的价格昂贵。为充分利用现有的冰洲石资源,本文通过热处理的方法对黄色和紫色冰洲石晶体的颜色进行了改善。通过大量实验,我们发现,黄色和紫色冰洲石晶体在加热到一定温度时颜色会发生变化,

  • [会议] Effects of One-dimensional Photonic Crystal on Thin Film Silicon Solar Cells

    We have designed lateral contact thin film silicon-based solar cells with and without one-dimensional photonic crystals as back surface field layer. The photonic crystal comprises a distributed Bragg reflector(DBR) for trapping the light. Simulations demonstrate that energy conversion efficiency and short circuit current ISC for c-Si solar cells with the photonic crystal structure are increased to 21.11% and 27.0 mA, respectively, from 18.33% and 22.8mA of the one without photonic crystal. In addition, the effects of DBRs consisting of different materials are investigated in our simulations. When the refractive index difference between sub-layers of the DBR is larger, the forbidden band width is broader, the reflectance of the DBR is higher, and more photons are reflected and trapped into the active region, then the absorption efficiency and the energy conversion efficiency of the solar cell are both increased. The bigger the refractive index difference of the DBR's sub-layers is, the broader the forbidden band width is. In addition, a-Si solar cells with and without DBR are also discussed.

  • [会议] 阳极氧化铝光子晶体的光学性质及应用

    光子晶体是一种周期性的介电结构。这种结构会对光产生强的布拉格散射,因此也就会在周期维度上产生一个完全的光子带隙。当光或电磁波的频率落在光子带隙中时,光的传播是被完全禁止的。光子晶体是一种新型的光学前沿材料,为控制光的传播提供了一种新的方法。阳极氧化铝光子晶体是基于阳极氧化铝的方法制备的一种光子晶体,这种光子晶体是在孔生长方向上具有主干孔层和分叉孔层周期性交替生长而得到的。孔层的厚度及

  • [会议] Effect of yttria content on phase stability and grain growth in Y_2O_3-ZrO_2 coupling MgAl_2O_4 dispersed phase

    The tetragonal yttria-stabilized zirconia polycrystal coupling MgAl_2O_4(3YTZP-30 vol.%MgAl_2O_4) exhibited the best high-strain-rate superplasticity in the binary systems, but few investigation had aimed at the effect of Y_2O_3 on the related phase stability and grain growth.In this work,the specimens of Y_2O_3-ZrO_2 coupling MgAl_2O_4(YSZ-spinel) were prepared by co-precipitation,air-sintering and hot-isostatic-pressing(HIPing).

  • [会议] 掺杂zr对奈米晶质子传导锶铈锆氧化物烧结行为之影响

    本研究成功地以固态反应法合成奈米晶质子传导鳃铈锆氧化物(SrCe_(1-x)Zr_xO_(3-δ)(SCZx)(0.0≦x≦0.5))粉体.并且利用X光绕射分析(XRD)、扫瞄式电子显微镜(SEM)观察及热机械分析(TMA)来针对Zr掺杂量对与质子传导锶铈锆氧化物的微结构、收缩率及烧结性做有系统的探讨.结果显示经1450℃烧结后之SCZx氧化物可以获得无杂相的钙钛矿结构.由于Z的掺杂会降低本氧化物的烧结性,所以由SEM观察

  • [会议] 影响三维woodpile型金红石二氧化钛光子晶体完全禁带的主要因素研究

    基于平面波展开法,用Bandsolve软件分别计算得到最大完全禁带,研究介电常数、填充率对woodpile光子晶体结构完全禁带的影响,给出了介电常数及填充比发生变化时光子禁带的变化规律,并总结了不同介质棒宽度,不同间距的woodpile结构对应的光子晶体的归一化频率的位置和范围。模拟结构显示,当woodpile的结构确定以后,归一化频率随着介电常数的增大而减小;当woodpile结构中介质棒的间距确定以后,归一化的频率随着介质棒的宽度增大而减小;当woodpile结构中介质棒的宽度确定以后,归一化的频率随着介质棒之间间距的增大而增大。

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