本体聚合聚丙烯的共混改性研究

本文研究了用化学降解法降低本体聚合聚丙烯的分子量,以改进加工流动性;并用共混改性方法改善降解后的聚丙烯的低温抗冲性能,得到室温和低温力学性能好而加工流动性也好的改性聚丙烯树脂。     

PLD制备FePt：MgO薄膜的结构及线性光学性能研究

采用脉冲激光沉积法（PLD）制备了FePt：MgO多层复合薄膜。采用高分辨透射电子显微镜（HRTEM）分析了薄膜的结构;采用紫外可见分光光度计分析了薄膜的线性光学性能。HRTEM分析表明基质MgO在单晶MgO衬底上同质外延生长,而FePt纳米颗粒周期性均匀地自组织嵌埋在MgO基质中。HRTEM的快速傅里叶变换（FFT）图表明,FePt纳米颗粒为富Pt的面心立方（FCC）结构的FePt3,其晶格常数αFePt3=3.90 。（1。=0.1 nm）。MgO基质与FePt纳米颗粒的界面分析表明,它们的界面处几乎不存在非晶层,只在FePt纳米颗粒与MgO基质的晶界线附近有少量的刃型位错。薄膜的紫外可见吸收谱结果表明,低脉冲数样品具有远紫外增透作用,高脉冲数样品存在3个表面等离子激元共振吸收峰,随FePt沉积脉冲数增加,吸收峰位置均发生红移,峰强逐渐减弱,峰强比规律变化。     

Ni∶MgO纳米复合薄膜的结构及其光学性质研究

采用脉冲激光气相沉积技术,将Ni纳米颗粒嵌埋在MgO薄膜中,形成Ni∶MgO纳米复合薄膜(Ni NCs∶MgO)。分别采用高分辨X射线衍射技术和紫外-可见吸收光谱详细研究了薄膜的晶体结构及光学性质。HRXRD结果表明MgO薄膜和Ni纳米颗粒都沿着(200)方向生长;由于Ni纳米颗粒的嵌埋,导致MgO基质发生了晶格畸变,从而使得MgO基质的晶格常数发生改变;晶格畸变也导致MgO的衍射峰被展宽;Ni的含量与其颗粒尺寸随着沉积Ni的激光脉冲数的增加而增加。紫外-可见吸收光谱的分析结果表明在190～600nm波长范围内薄膜的吸收峰是Ni纳米颗粒的表面等离激元共振吸收峰;随着沉积Ni激光脉冲数的增加,单个吸收峰强度增强的同时还发生了红移;当沉积Ni的激光脉冲数从200增加到250时,吸收峰发生劈裂。     

PECVD 制程中N+ A-SI Layer沉积最佳工艺参数的探究北大核心CSCD

本文采取4因子4水平田口设计,用等离子体增强化学气相沉积法制备了沉积在白玻璃上的单层N+A-SI:H薄膜,测试了薄膜的应力,膜厚,折射率,透过率,及SI-H/N-H键含量,综合评价不同参数配比条件下N+A-SI:H单层膜的膜质表现,针对比较重要的参数:沉积速率,Thickness Uniformity,SI-H键含量进行了田口分析,两阶段策略优化选出PECVD制程中的N+A-SI layer的最佳参数配比为:Pressure-385.7 Pa,Spacing-20.32 mm,RF Power-13000W,Gas Ratio-3.12。     

The micro-structural studies of Ni-BaTiO<Subscript>3</Subscript> nanocomposite films by TEM and EELS

Epitaxial BaTiO3 films with embedded metallic Ni nanocrystal (Ni-BaTiO3) were successfully fabricated on SrTiO3 (001) single-crystalline substrate through the laser molecular beam epitaxial (L-MBE) technique.High resolution transmission electron microscopy (HRTEM) and electron energy loss spectrum (EELS) with Kramers-Kronig analysis methods were employed to characterize the microstructures,elementary distribution and the electron structure of these films.HRTEM results suggested that the structure of BaTiO3 was tetragonal with lattice parameters of a=0.399 nm and c=0.403 nm.Energy dispersive X-Ray spectroscopy (EDX) confirmed metallic Ni nanocrystal embedded successfully in BaTiO3 epitaxial films.The Ni-BaTiO3 composite films were compound of the epitaxial BaTiO3 (110) layers alternating with Ni NCs array (111) layers.Furthermore,the existence of the misfit dislocations induced by the embedding of Ni nanoparticles was also clearly demonstrated by the HRTEM images.The Ni L2,3 edges of EELS revealed that Ni NCs in their metallic state were embedded uniformly in the BaTiO3 matrix.A chemical shift of about 7 eV regarding L3 edges in the Ni EELS was also observed.The optical band gap of BaTiO3 in these films was about 3.84 eV,higher than 3.55 eV for pure BaTiO3 films at room temperature.