抗氧化锡纳米粒子的制备方法和热性能研究

抗氧化锡纳米粒子主要是通过化学还原方法制备而成,文中研究分析了其的尺寸和热学性能。锡纳米粒子的X射线衍射分析结果显示这些纳米粒子并未被氧化,其的示差扫描量热法分析证实了粒子熔点随粒子尺寸变化而变化的情况。同时,测得文中合成的锡纳米颗粒熔点低达202.16 ℃。     

锑掺杂氧化锡纳米粉体的水热合成与表征

以SnCl4?5H2O、SbCl3为基本原料,采用水热合成法制得了锑掺杂氧化锡纳米粉体。运用XRD、TEM等分析测试手段研究了粉体的晶相组成、晶粒粒度和晶貌特征,并根据晶格常数研究了锑的掺杂形式。结果表明:在240~300℃的水热条件下,反应2~8h,可制得结晶良好、分散性好、粒度在3~15nm、具有四方晶系金红石结构的锑掺杂氧化锡球形颗粒;Sb是以Sb3+的形式进入SnO2晶格中。     

层状二硫化钼光催化产氢的研究进展

单层或少数层MoS2是一种具有类石墨烯结构的新型二维层状化合物,拥有超薄的厚度、适宜的禁带宽度及独特的电学和光学性质,在场效应管、气体传感器、光探测器、锂电池和超电容等领域有广泛的应用价值.凭借其边缘悬挂键析氢催化活性高、比表面积大、抗光腐蚀性强等优点,二维MoS2在光催化应用上展现了良好的潜力.介绍了二维MoS2多样的晶体结构,分析了其能带可调、可见光吸收及催化析氢等特性,综述了二维MoS2从电催化析氢到光催化析氢的研究进展,并结合自身研究展望了单层MoS2作为直接光催化剂的潜在优势及其挑战.     

基于小波的2-D分形布朗运动分析与合成

1/f分形随机过程广泛地存在于各种自然现象和社会现象中,日益成为信号检测与估计、信号处理及图像处理的研究热点.分形布朗运动是模拟此类信号的很好的数学模型.小波因其所具有的多尺度分析能力成为分析分形信号的有力工具.本文分析了二维分形布朗运动经小波变换后各尺度间小波系数相关结构的特性,提出了一种合成二维分形布朗运动的算法,并展示了其在和谐图案生成上的应用.     

二硫化钼-石墨烯垂直异质结的制备与表征

以采用化学气相沉积法(CVD)生长的单层石墨烯为导电电极、四硫代钼酸铵水溶液为电解质,通过电化学沉积法合成了二硫化钼/石墨烯(MoS2/graphene)垂直异质结。将合成的MoS2/graphene垂直异质结通过CVD在氢气(H2)和氩气(Ar)环境下进行退火处理。利用拉曼光谱、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、原子力显微镜(AFM)系统地分析了样品的物质成分、表面形貌和厚度等。这种简单、环保、低成本的制备大面积MoS2/graphene垂直异质结的方法具有普遍适用性,为其他垂直异质结的制备开辟了新途径。     

Giant Nonlinear Optical Absorption of Ion-Intercalated Tin Disulfide Associated with Abundant In-Gap Defects

Herein it is reported that electrochemical ion-intercalation is a convenient and effective strategy toward materials with giant nonlinear optical (NLO) absorption. Alkali-metal ions (i.e., Li⁺, Na⁺, K⁺) are electrochemically intercalated into SnS₂ nanosheets. All ion-intercalated samples exhibit remarkably enhanced optical nonlinearity compared with an untreated sample, and Li-intercalated SnS₂ (Li_0.952Sn^II_0.398Sn^IV_0.563S₂) possesses optimized strong NLO performance. Li_0.952Sn^II_0.398Sn^IV_0.563S₂ exhibits strong saturable absorption, and the corresponding nonlinear absorption coefficient (β_eff) is -1.7 × 10⁴ cm GW^–1 for the laser excitation at 515 nm. Li_0.952Sn^II_0.398Sn^IV_0.563S₂ shows prominent reverse saturable absorption with the laser excitation at 800 nm (β_eff: 2.8 × 10⁴ cm GW^–1) and 1030 nm (β_eff: 1.4 × 10⁴ cm GW^–1). All β_eff values are larger than most of the reported inorganic NLO materials at corresponding wavelengths. The optical limiting threshold of Li_0.952Sn^II_0.398Sn^IV_0.563S₂ is 8 × 10^–4 J cm^–2, two orders of magnitude smaller (better) than the bench-mark composite (e.g., SWNT-NH-TPP). Ion intercalation introduces abundant in-gap defects. The excitation of electrons in in-gap states to conduction band intensifies the Pauli-blocking effect and therefore promotes the saturable absorption under the 515 nm laser excitation, while the in-gap defect states acting as effective excitation pathway facilitate excited-state absorption for 800 and 1030 nm laser.     

Transforming One‐Dimensional Nanowalls to Long‐Range Ordered Two‐Dimensional Nanowaves: Exploiting Buckling Instability and Nanofibers Effect in Holographic Lithography

Two‐dimensional nanowaves with long‐range order are fabricated by exploiting swelling‐induced buckling of one‐dimensional (1D) nanowalls with nanofibers formed in‐between during holographic lithography of the negative‐tone photoresist SU‐8. The 1D film goes through a constrained swelling in the development stage, and becomes buckled above the critical threshold. The degree of lateral undulation can be controlled by tuning the pattern aspect ratio (height/width) and exposure dosage. At a high aspect ratio (e.g., 6) and a high exposure dosage, nanofibers (30–50 nm in diameter) are formed between the nanowalls as a result of overlapping of low crosslinking density regions. By comparing experimental results with finite‐element analysis, the buckling mechanism is investigated, which confirms that the nanofibers prevent the deformed nanowalls from recovery to their original state, thus, leading to long‐range ordered two‐dimensional (2D) wavy structures. The film with nanowaves show weaker reflecting color under an ambient light and lower transmittance compared to the straight nanowalls. Using double exposure through a photomask, patterns consisting of both nanowaves and nanowalls for optical display are created.     

A Facile Synthesis and Characterization of Monodisperse Spherical Pigment Particles with a Core/Shell Structure

In this paper, a facile sol–gel process for producing monodisperse, spherical, and nonaggregated pigment particles with a core/shell structure is reported. Spherical silica particles (245 and 385 nm in diameter) and Cr₂O₃, α‐Fe₂O₃, ZnCo₂O₄, CuFeCrO₄, MgFe₂O₄, and CoAl₂O₄ pigments are selected as cores and shells, respectively. The obtained core/shell‐structured pigment samples, denoted as SiO₂@Cr₂O₃ (green), SiO₂@α‐Fe₂O₃ (red), SiO₂@MgFe₂O₄ (brown), SiO₂@ZnCo₂O₄ (dark green), SiO₂@CoAl₂O₄ (blue), and SiO₂@CuFeCrO₄ (black), are well characterized by using X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and UV‐vis diffuse reflection, as well as by investigating the magnetic properties. The results of XRD and high‐resolution TEM (HRTEM) demonstrate that the pigment shells crystallize well on the surface of SiO₂ particles. The thickness of the pigment shell can be tuned by the number of coatings, to some extent. These pigment particles can be well dispersed in some solvents (such as glycol) to form relatively more stable suspensions than the commercial products. Apart from the color characteristics, some of pigments like SiO₂@Cr₂O₃, SiO₂@MgFe₂O₄, and SiO₂@CuFeCrO₄ also show magnetic properties with coercivities of 1098 Oe (5 K), 648 Oe (5 K), and 91 Oe (298 K), respectively.     

Two Dimensional Array of Antenna-Coupled Microbolometers

Antenna-coupled microbolometers are known for having short time constants and high responsivity, but their small dimensions make them unsuitable for imaging applications where a typical pixel area is generally greater than 20 × 20 μm². In this paper a two dimensional array of antenna-coupled microbolometers is demonstrated as an area receiver. Using the response of microbolometers to visible frequencies a two-dimensional diagnostic scan in the visible was performed on these arrays which allowed measurement of their homogeneity. Frequency response measurements gave time constants around 130 nsec, similar to the ones obtained for single element microbolometers which indicates that a detector of virtually any size can be fabricated without sacrificing time response. Response and noise measurements show lower noise and higher responsivity compared to single element microbolometers. These results make two-dimensional arrays of antenna-coupled microbolometers a promising option for development of pixels in infrared focal plane arrays.     

二维电子气简介

本文简要介绍了液氦表面、半导体表面空间电荷层和化合物半导体异质结界面的二维电子气.积累在选择掺杂GaAs/Al_xGa_(1-x)A_s异质结界面的二维电子气在低温下迁移率剧增.调制掺杂GaAs/Al_xGa_(1-x)A_s超晶格是一个适合于研究量子态和次带能级的系统.因而,异质结界面处二维电子气的研究,不仅可能为新的高速和微波器件的探索打开新的途径,而且还提供了研究量子效应的新领域.     

二维电子倍增器及其新发展

概述了二维电子倍增器ＲＬＳＧ－ＭＣＰ的发展的概况和工艺和局限性,提出了用半导体工艺制作ＡＴ－ＭＣＰ的技术途径,阐述了ＡＴ－ＭＣＰ的优点;介绍了新型ＭＳＰ电子倍增器的原理和特点,最后展望了电子倍增器的发展前景。     

Composites of Perylene Chromophores and Layered Double Hydroxides: Direct Synthesis,Characterization, and Photo‐ and Chemical Stability

Composites of the tetra‐anion of the perylene dye N,N′‐di(phenyl‐3,5‐disulfonic acid)perylene‐3,4:9,10‐tetracarboxydiimide (PBITS) with layered double hydroxides (LDHs) were formed by direct synthesis (co‐precipitation at constant pH). The LDHs were of the hydrotalcite (Mg–Al–OH and Zn–Al–OH compositions). During synthesis of the hydrocalumite type (Ca–Al–OH), partial destruction of the dye occurs, being more pronounced at higher pH values. The composites were characterized with regard to their composition by elemental and thermal analysis. From UV‐vis spectroscopic data and powder X‐ray diffraction, a structural model is developed for the composites. In the galleries between the hydroxide layers, the chromophore molecules are stacked in an J‐type arrangement. The compounds have brilliant colors and are insoluble in common solvents. With regard to a possible application as pigments, their photostability and their chemical resistance against a typical application environment was tested. The photostability of the dye molecules and their chemical resistance against setting cement are slightly raised by the occlusion within the LDH structure; however, the photostability of the LDH–cement is lower than that of cement colored with the pure perylene dye.     

锡酞菁及其磺化衍生物的合成与性质研究

以苯酐和氯化亚锡为原料,采用固相法合成锡酞菁(SnPc),再和发烟硫酸反应合成磺化锡酞菁(SnPcS)。用元素分析,红外光谱,紫外光谱对它们进行了表征。结果表明:磺化锡酞菁的溶解性比锡酞菁要大得多;热稳定性研究发现,磺化锡酞菁从100℃开始失去磺酸基,400℃酞菁环才开始分解;且磺化锡酞菁在水中的氧化还原过程具有可逆性;同时,对磺化锡酞菁的电子光谱进行了研究。     

MSM光电探测器特性二维数值模拟

为了解释在InGaAs金属-半导体-金属光电探测器(MSM—PD)内光产生载流子的行为及器件内电场分布,本文用有限元法数值求解了含复合项的二维泊松方程、电流连续方程及电荷俘获速率方程。得到了InGaAs MSM光电探测器的电流—电压特性及器件内电场和载流子分布。模拟结果解释了实验观察到的雪崩击穿现象,并表明电子电流比空穴电流提前饱和。     

四元数在二维波达方向估计中的应用

基于四元数,本文提出了一种针对双平行阵的二维波达方向估计方法。与复数不同,四元数是一种维数更高的多元数代数。利用四元数代数理论,波达方向估计问题可以以高维的角度来求解。本文将四元数的概念引入到双平行阵接收模型中,建立了双平行阵的四元数接收模型。所提算法利用四元数的不同基之间的共同特性,对四元数子空间与信号方向矢量的正交关系进行解耦,得到仅含方位角信息的方向矢量与四元数子空间的正交表达式,并通过一维搜索估计出方位角。根据得到的方位角,算法进一步估计得到信源的俯仰角。仿真实验验证了本文所提算法的有效性。      

One‐Dimensional Metal‐Oxide Nanostructures: Recent Developments in Synthesis,Characterization, and Applications

1D metal‐oxide nanostructures have attracted much attention because metal oxides are the most fascinating functional materials. The 1D morphologies can easily enhance the unique properties of the metal‐oxide nanostructures, which make them suitable for a wide variety of applications, including gas sensors, electrochromic devices, light‐emitting diodes, field emitters, supercapacitors, nanoelectronics, and nanogenerators. Therefore, much effort has been made to synthesize and characterize 1D metal‐oxide nanostructures in the forms of nanorods, nanowires, nanotubes, nanobelts, etc. Various physical and chemical deposition techniques and growth mechanisms are exploited and developed to control the morphology, identical shape, uniform size, perfect crystalline structure, defects, and homogenous stoichiometry of the 1D metal‐oxide nanostructures. Here a comprehensive review of recent developments in novel synthesis, exceptional characteristics, and prominent applications of one‐dimensional nanostructures of tungsten oxides, molybdenum oxides, tantalum oxides, vanadium oxides, niobium oxides, titanium oxides, nickel oxides, zinc oxides, bismuth oxides, and tin oxides is provided.     

Modeling and Simulating for Two Dimensional Infrared Photonic Crystal Devices

In order to design infrared devices efficiently, dispersive properties of two dimensional photonic crystal is studied in this paper. A model of eigenfrequencies is created by combining the variational expression with the conformal finite-difference time-domain (C-FDTD) technique. Useful data obtained by presentation can be applied to the analysis of the dispersion curves and design of the near-infrared waveguides.     

二维离子注入的改进模型及数值模拟

本文提出了一个改进的二维离子注入模型.对于在任意形状掩蔽边界下的离子注入分布,我们在纵向采用联结的半高斯分布或修改过的Pearson-IV分布,在横向采用余误差函数分布,并且考虑了在多层掩蔽情况下各种材料阻止本领的不同.利用这一模型发展起来的离子注入模拟器能连续计算多次不同能量、剂量和杂质类型的注入分布,并考虑了多种不同掩蔽边界的影响.通过与其它工艺模拟器的比较,表明我们的模拟器在精度和功能上都有明显的改进.     

深亚微米MOSFET二维数值模拟的若干结果

对溶亚微米器件，由于工作电压下降，要求重新确定ＬＤＤ和常规ＭＯＳＦＥＴ在ＶＬＳＩ中的作用。本文从基本器件数理方程发出，对深亚微米常规及ＬＤＤ ＭＯＳＦＥＴ的器件特性、热载流子效应及短沟道效应进行了二维稳态数值模拟，指出了常规和ＬＤＤ ＭＯＳＦＥＴ各自的局限性，明确了在深亚微米ＶＬＳＩ中，ＬＤＤ仍然起主要作用。     

二维振动方向变换器的耦合振动

通过耦合振动理论、模态分析和实验测量研究了二维振动方向变换器的耦合振动的谐振频率方程和特定输出端的位移振幅。实验结果表明,理论分析得出的纵向振动谐振频率与实验结果相符,且通过实验与模态分析可知,此二维振动方向变换器有很好的聚能作用。