支化侧链偶氮聚电解质的光致二向色性和表面起伏光栅

通过后重氮偶合的方法合成了两种含支化侧链偶氮苯生色团的聚电解质PBANT AC和PBACT AC .用红外光谱、氢核磁共振谱、紫外 可见光光谱、热分析和元素分析等手段对聚合物的结构和性能进行了表征 .在 4 88nm的偏振Ar+ 激光的照射下 ,聚合物薄膜中的偶氮苯生色团可发生光致取向 ,取向有序度分别为 0 12和 0 0 9.在干涉偏振激光束的照射下 ,两种聚合物旋涂膜表面均形成了规则的正弦表面起伏光栅 ,其起伏深度分别为 4 0nm和 80nm左右 .用氦氖激光实时检测 ,测定了两种旋涂膜表面起伏光栅的一级衍射效率随光照时间的变化关系 .     

一种具有可逆光加工特性的偶氮聚电解质的合成与表征

合成一种具有可逆光加工特性的偶氮聚电解质(PAA-AZ),用核磁、热分析、紫外-可见光谱、接触角及GPC等手段对其进行了结构和性能表征.PAA-AZ的旋涂膜用线偏振Ar+激光照射一段时间,在原子力显微镜(AFM)下观测其表面,膜表面形成了规整有序纳米尺寸的三维表面图案表面起伏光栅(起伏深度为100nm).用氦氖激光检测了PAA-AZ旋涂膜一级衍射效率与光照时间的关系.     

Co掺杂ZnO纳米棒的水热法制备及其光致发光性能

以Zn(NO3)2·6H2O 和Co(NO3)2·6H2O为原料, 通过水热法在较低温度下制备了纯ZnO和Co掺杂的ZnO(ZnO:Co)纳米棒. 利用XRD、EDS、TEM和HRTEM对样品进行了表征, 结合光致发光(PL)谱研究了样品的PL性能. 结果表明, 水热法制备纯ZnO和ZnO:Co纳米棒均具有较好的结晶度. Co2+是以替代的形式进入ZnO晶格, 掺入量为2%(原子分数)左右. 纯的ZnO纳米棒平均直径约为20 nm, 平均长度约为180 nm; 掺杂样品的平均直径值约为15 nm, 平均长度约为200 nm左右; Co掺杂轻微地影响ZnO纳米棒的生长. 另外, Co掺杂能够调整ZnO纳米棒的能带结构、提高表面态含量, 进而使得ZnO:Co纳米棒的紫外发光峰位红移, 可见光发光能力增强.     

二氧化钛表面包覆氧化硅纳米膜的热力学研究

热力学计算结果表明,氧化硅的临界成核半径为2.8nm.由起伏引起的核胚如果小于2.8nm则不会形成晶核而继续生长.上述热力学分析虽然是半理想化的,但是非常有效.可以找到这样一个体系,其溶液条件不发生均匀成核,而是异相表面成核.这在理论上为氧化硅包覆在二氧化钛表面形成均匀膜而不生成单独的氧化硅相提供了可能.     

Jeffamine聚醚胺改性合成介孔及超微孔氧化硅微球

通过对Jeffamine ED2003进行硬脂酸接枝,获得了一种在水溶液中能够进行自组装的新型聚醚酰胺高分子表面活性剂,命名为ED2003-fa-18.以ED2003-fa-18聚醚酰胺高分子表面活性剂为模板,以正硅酸乙酯(TEOS)为无机硅源,在酸性条件下水热合成了介孔及超微孔氧化硅微球.利用粉末X射线衍射(XRD)、N₂物理吸附、红外光谱(IR)、核磁共振波谱(¹H NMR)、扫描电镜(SEM)和透射电镜(TEM)等方法对合成样品进行了表征.研究结果表明,通过改变合成体系中表面活性剂的浓度,可控合成出了有序的介孔及超微孔氧化硅材料.当ED2003-fa-18的浓度为1wt%时,合成的材料为介孔氧化硅,样品的最可几孔径约为2.2 nm.当ED2003-fa-18的浓度从3wt%增加到7wt%时,样品的最可几孔径从1.98 nm减小到1.94 nm,得到的样品为超微孔氧化硅材料.样品的比表面积在500 m²·g^-1左右,孔体积在0.3 cm³·g^-1左右.由SEM照片可知,所合成的介孔及超微孔氧化硅材料均为由20~30 nm的球形纳米颗粒进一步团聚形成的2~4 μm的紧密堆积的实心微球.     

W(100)c(2×2)表面的STM图像

用基于第一性原理的密度泛函理论研究了W(100)c(2×2)再构表面的表面弛豫以及扫描隧道显微镜(STM)图像和衬底偏压的关系.计算所得到的表面原子沿[110]方向的畸变位移δ为0.027nm,畸变能△E为80.6meV·atom-1,表面原子的弛豫分别为-7.6%(△d12/d0)和 0.8%(△d23/d0),功函数Φ为4.55eV.STM图像模拟表明,由于表面原子沿[110]方向的位移,会导致出现平行于[110]方向的亮暗带状条纹.STM图像中突起所对应的并不是表面或次表面的钨原子,而是zig-zag型W原子链中线位置;而STM暗区对应于原子位置畸变形成的相邻zig-zag型W原子链中间区域.当衬底负偏压时,STM针尖典型起伏高度大约在0.008-0.013nm之间;而当衬底正偏压时,针尖起伏高度在0.019-0.024nm之间变化.     

W(100) c(2×2)表面的STM图像

用基于第一性原理的密度泛函理论研究了W(100) c(2×2)再构表面的表面弛豫以及扫描隧道显微镜(STM)图像和衬底偏压的关系. 计算所得到的表面原子沿[-110]方向的畸变位移δ为0.027 nm, 畸变能⊿E为80.6 meV·atom-1, 表面原子的弛豫分别为-7.6%(⊿d12/d0)和+0.8%(⊿d23/d0), 功函数Φ为4.55 eV. STM图像模拟表明, 由于表面原子沿[-110]方向的位移, 会导致出现平行于[110]方向的亮暗带状条纹. STM图像中突起所对应的并不是表面或次表面的钨原子, 而是zig-zag型W 原子链中线位置; 而STM暗区对应于原子位置畸变形成的相邻zig-zag型W原子链中间区域. 当衬底负偏压时, STM针尖典型起伏高度大约在0.008-0.013 nm之间; 而当衬底正偏压时, 针尖起伏高度在0.019-0.024 nm之间变化.     

水热法制备表面修饰的钛酸锶纳米微粉

以工业原料和常用试剂TiCl4、Sr(NO3)2和KOH为基础原料,通过添加表面活性剂十二烷基苯磺酸(DBS),采用水热法制备出表面包裹有DBS的钛酸锶纳米微粉,并应用红外光谱,X射线衍射谱,透射电子显微镜,热分析等一系列手段对其微结构进行了表征.结果表明:样品为表面包裹有DBS的钛酸锶纳米微粉,其形状较为规则,粒度分布较窄,单分散性较好.粒子的平均粒径为120nm,包裹膜的平均厚度为6nm左右.根据X光谱测量,表面修饰后的钛酸锶纳米微粉均以立方相存在.一般体相钛酸锶微粉为极性粉体.而表面修饰后的钛酸锶纳米微粉能够较为稳定地悬浮于非极性液体如正己烷中,说明SrTiO3粉体的极性表面被DBS包裹后,变为非极性.     

纳米晶二氧化钛光声与表面光伏特性

利用溶胶-凝胶法制备二氧化钛纳米晶粉末. 结合光声和表面光伏技术对样品表面态性质和光诱导电荷输运特性进行研究. 结果表明, 纳米晶TiO2样品在波长为380 nm 处出现的表面光伏响应与锐钛矿型TiO2的表面电子结构有关, 属于带鄄带电荷转移跃迁;随着样品粒径的减小, 在2.38 eV 能级处形成一个具有明显受体特征的表面电子态; 依据样品光声效应和表面光伏效应之间的能量互补关系发现, 尽管随着样品平均粒径的减小无辐射跃迁产生的光声信号增强, 但是适当提高样品中金红石的相对含量, 可以显著减少样品表面无辐射跃迁的成分, 提高光量子效率.     

主链型聚氨酯光动力高分子的合成与表征

合成了一种主链含推拉电子型偶氮苯基团的聚氨酯光动力高分子 .对聚合物的结构、热性能及光学性能进行了表征 .此聚合物为主链含假芪型偶氮生色团的无定形高分子 .用 4 88nmAr+ 激光对聚合物薄膜进行光加工 ,得到了规则的正弦表面起伏光栅 ,其起伏深度大于 2 0 0nm .光栅的一级衍射效率可达 2 4 % .     

Annealing effects on the morphology and luminescence of cubic boron nitride based ceramics

Cubic boron nitride based ceramics with silicon were sintered at 1350 °C under a pressure of 5.0 GPa. The effects of post-annealing on grain morphology, surface morphology, and photoluminescence of Si–cBN ceramics were investigated by scanning electron microscope and room temperature photoluminescence measurements. The results showed that the annealing treatment had great influence on cBN grain morphology, rather than the surface morphology. The luminescence intensity increased with annealing temperature and annealing time. The void-net structure formed by continuous distribution of SiO_x particulate on the ceramic surface resulted in the emission band peaking at about 701.2 nm, and the tense passivation of Si by SiO_x led to the peak's low intensity. The near ultraviolet emission band peaking at about 317 nm was attributed to the oxygen vacancies formed in cBN grain surface, caused by the scavenging of oxygen from the cBN grain surface by the added Si.     

[Fe(CN)6]4-在溴碘化银T-颗粒乳剂中的掺杂

本文研究了K₄[Fe(CN)₆]掺杂对溴碘化银T-颗粒乳剂感光性能的影响.结果表明,掺杂剂的掺杂量以及掺杂位置对乳剂的感光性能都有影响.K₄[Fe(CN)₆]的掺杂量在每克乳剂31×10^-9-31×10^-11mol之间时,乳剂感光度都有提高.最佳掺杂量为每克乳剂31×10-10mol.掺杂位置接近表面时效果相对较好,表明K₄[Fe(CN)₆]是浅电子陷阱掺杂剂.当掺杂剂的掺杂量大于每克乳剂31×10^-8mol,且掺杂位置在乳剂颗粒较深内部时,乳剂的感光度反而下降.     

Surface chemistry and diffusion of trace and alloying elements during in vacuum thermal deoxidation of stainless steel

Removal of the native surface oxide from steel is an important initial step during vacuum brazing. Trace and alloying elements in steel, such as Mn, Si, and Ni, can diffuse to the surface and influence the deoxidation process. The detailed surface chemical composition and grain morphology of the common stainless-steel grade 316L is imaged and spectroscopically analyzed at several stages of in-vacuum annealing from room temperature up to 850°C. Measurements are performed using synchrotron-based X-ray photoemission and low-energy electron microscopy (XPEEM/LEEM). The initial native Cr surface oxide is amorphous and unaffected by the underlying Fe grain morphology. After annealing to ~700°C, the grain morphology is seen at the surface, persisting also after the complete oxygen removal at 850°C. The surface concentration of first Mn and then Si increases significantly when annealing to 500°C and 700°C, respectively, while Ni and Cr concentrations do not change. Mn and Si are not located only in grain boundaries or clusters but are distributed across over the surface. Both Mn and Si appear as oxides, while Cr oxide becomes metallic Cr. Annealing from 500°C up to 850°C leads to the removal of first the Mn and then Si oxides from the surface, while Cr and Fe are completely reduced to metals. Deoxidation of Cr occurs faster at the grain boundaries, and the final Cr metal surface content varies between the grains. The findings are summarized in a general qualitative model, relevant for austenite steels.     

PLA-b-PEO-b-PLA三嵌段共聚物分子聚集体性质的研究

采用开环聚合的方法 ,合成了组成不同的PLA b PEO b PLA三嵌段共聚物 .滴加选择性溶剂水于共聚物的良溶剂溶液中 ,制备了共聚物以水为介质的“平头”聚集体胶束溶液 .把聚集体胶束溶液浇铸在云母片上 ,采用扫描探针显微镜 (SPM)表征了其形貌和表面微粘弹性 .发现脱离了极性介质水的聚集体的表面性质发生了不均一化 ,聚集体的顶部比相连接的部分具有较高的储能模量 .聚集体环境的改变使聚集体中不同嵌段的迁移导致了这种表面粘弹性的不均一 .另外 ,采用动态光散射的方法测量了体系溶液中聚集体胶束的尺寸 .实验发现光散射所得到的聚集体的尺寸远远大于SPM所得到尺寸 .增加聚合物的起始浓度使聚集体胶束的尺寸以及多分散性都在不同程度上增大 .然而聚合物的不同 ,这种增加的程度会有比较大的差别     

Microstructural investigation of nickel deposits obtained by pulsed current

Electrodeposited nickel coatings are applied in functional applications to modify or improve corrosion resistance, hardness, wear, magnetic, and other properties. In this work, Nickel deposits were produced by simple pulse electrodeposition using a free-additive Watts bath. It has been shown that pulse current deposition is able to produce coatings with excellent properties in morphology, particle distribution, structure, grain size, hardness and wear resistance. Pulsed techniques present a larger number of variables, so we propose to optimize the parameters which define the pulsed current to obtain deposits with improved properties. The optimization of the conditions of deposition was established and the influence of pulse parameters, namely, pulse on-time, off-time and average current density, on the grain size, surface morphology and crystal orientation was determined. The morphology of the coatings was characterized by observations in scanning electronic microscopy (SEM). X-ray diffraction in symmetric mode was also used to evaluate the structure and principal crystallographic orientations of the deposits. The study showed that pulse current results in better properties of deposits and significantly refined the crystal grain.     

铱盐在AgBr乳剂中的作用

用(NH₄)₃IrCl₆(Ⅲ)和(NH₄)IrCl₆(Ⅳ)分别对立方体AgBr乳剂颗粒表面和内部进行敏化,用表面显影和内部显影的方法,对铱盐在乳剂颗粒中的作用进行了研究。实验表明,经铱表敏的AgBr乳剂表面感光度增加,而铱内敏的AgBr乳剂表面感光度降低,内部感光度增加;铱内敏并经灰化的乳剂在曝光后能形成直接正像。这是因为经化学灰化的铱内敏乳剂在曝光后,光生电子被乳剂颗粒内部的铱中心捕获而形成内潜影,光空穴则破坏颗粒表面的灰化中心,使其不能显影。因此,我们认为铱在乳剂颗粒内部起着电子陷阱的作用。     

金在铱内敏的直接正像乳剂中的作用

制备依内敏的AgBr立方体乳剂,乳剂被二氧化硫脲和三氯化金灰化。实验表明:有金存在时灰化乳剂,灰化中心优先在颗粒表面形成;金不存在时,则灰化中心优先在颗粒内部形成。用Na₁S₂O₃溶液刻蚀乳剂,得到了灰化中心在乳剂颗粒体相中的分布曲线。当二氧化硫脲量小,加金灰化时,灰化中心分布在颗粒表面和次表面;当二氧化硫脲量大,加金灰化时,灰化中心分布在颗粒体相中,但由表到里,灰化中心越来越少;当二氧化硫脲量大,不加金灰化时,灰化中心主要分布在颗粒中层部分。对加金灰化的乳剂来说,由于颗粒内部没有灰化中心竞争光生空穴,有大量的光生空穴破坏颗粒表面的灰化中心,因而可以获得高感直接正像乳剂。     

Improved Performance of All-Inorganic Perovskite Light-emitting Diodes via Nanostructured Stamp Imprinting

Halide perovskites are emerging emitters with excellent optoelectronic properties. Contrary to the large grain fabrication goal in perovskite solar cells, perovskite light-emitting diodes (PeLEDs) based on small grain enable efficient radiative recombination because of relatively higher charge carrier densities due to spatial confinement. However, achieving small-sized grain growth with superior crystal quality and film morphology remains a challenge. In this work, we demonstrated a nanostructured stamp thermal imprinting strategy to boost the surface coverage and improve the crystalline quality of CsPbBr₃ film, particularly confine the grain size, leading to the improvement of luminance and efficiency of PeLEDs. We improved the thermal imprinting process utilizing the nanostructured stamp to selectively manipulate the nucleation and growth in the nanoscale region and acquire small-sized grain accompanied by improved crystal quality and surface morphology of the film. By optimizing the imprinting pressure and the period of the nanostructures, appropriate grain size, high surface coverage, small surface roughness and improved crystallization could be achieved synchronously. Finally, the maximum luminance and efficiency of PeLEDs achieved by nanostructured stamp imprinting with a period of 320 nm are 67600 cd/m² and 16.36 cd/A, respectively. This corresponds to improvements of 123 % in luminance and 100 % in efficiency, compared to that of PeLEDs without the imprinting.     

Pulse plating effect on microstructure and corrosion properties of Zn–Ni alloy coatings

The influence of pulse plating parameters on the surface morphology, grain size, lattice imperfection and corrosion properties of Zn–Ni alloy has been studied. The coatings were electrodeposited in an alkaline cyanide-free solution. AFM was applied for surface morphology examination, XRD measurements were carried out for phase composition and texture analysis, electron probe microanalysis was used for alloy chemical composition studies, while electrochemical techniques were applied for corrosion performance evaluation. The pulse plated Zn–Ni coatings appeared to consist of the γ-Zn₂₁Ni₅ phase and the composition of the alloy depended on the plating parameters. The grain size, lattice imperfection and homogeneity of grain distribution were established to be the main factors determining corrosion behaviour of the coating. Presented at the 4th Baltic Conference on Electrochemistry, Greifswald, March 13–16, 2005