单双层石墨烯的制备及电导特性调控

石墨烯二维材料有着优异的物理、化学特性,在多个科学领域展现出广阔的应用前景.采用化学气相沉积方法在Cu-Ni合金表面制备了二维石墨烯薄膜并揭示其生长机制;研究生长时间、温度等对石墨烯覆盖度和晶格质量的影响.通过优化生长条件,成功制备了大面积单层及具有强烈层间耦合作用的AB堆叠双层石墨烯薄膜.进一步运用表面沉积技术在单层石墨烯上构建零维Au团簇和二维Au薄膜,研究其对石墨烯电导特性的影响;并结合第一性原理计算,揭示Au的形态及覆盖度影响石墨烯电导特性的规律.据此制作了石墨烯场效应晶体管器件,通过精确控制Au的覆盖度,实现石墨烯电导类型和载流子浓度的有效调控,拓展了其在微电子领域的应用.     

Bi_(1.6)La_(0.4)Ti_2O_7薄膜的制备及性能研究

采用化学溶液沉积法在ITO基片上制备不同退火温度的掺镧钛酸铋Bi1.6La0.4Ti2O7(BLT)薄膜。研究了其结构、介电性能、漏电流密度与外加电压I-V关系曲线和光学带隙。XRD射线衍射测试结果表明,经500、550、600℃1 h退火后的薄膜的主晶相为烧绿石结构,无杂相生成,600℃时BLT薄膜衍射峰比其他两种温度的强。在1 kHz频率下测得的介电常数、损耗因子分别为114,3%;129,3%;194,6%。BLT薄膜的漏电流密度与外加电压关系曲线表明,BLT薄膜600℃的漏电流比550和500℃稍微减小。通过透射谱分析得到BLT薄膜的光学带隙几乎不受温度影响,均为3.7 eV。这些结果表明制备BLT固溶体薄膜较佳为退火温度600℃,具有较好的性能,在光电器件有良好的应用前景。     

Microstructure and oxidation resistance of SiC–MoSi2 multi-phase coating for SiC coated C/C composites

In order to improve the anti-oxidation of C/C composites, a SiC–MoSi2multi-phase coating for SiC coated carbon/carbon composites(C/C)was prepared by low pressure chemical vapor deposition(LPCVD) using methyltrichlorosilane(MTS) as precursor, combined with slurry painting from MoSi2 powder. The phase composition and morphology were analyzed by scanning electron microscope(SEM) and X-ray diffraction(XRD) methods, and the deposition mechanism was discussed. The isothermal oxidation and thermal shock resistance were investigated in a furnace containing air environment at 1500 1C. The results show that the as-prepared SiC–MoSi2coating consists of MoSi2 particles as a dispersing phase and CVD–SiC as a continuous phase. The weight loss of the coated samples is 1.51% after oxidation at 1500 1C for 90 h, and 4.79% after 30 thermal cycles between 1500 1C and room temperature. The penetrable cracks and cavities in the coating served as the diffusion channel of oxygen, resulted in the oxidation of C/C composites, and led to the weight loss in oxidation.     

Cu衬底上ZnO纳米结构及其光催化性能分析

采用两步电化学沉积法在Cu衬底上沉积得到ZnO纳米结构薄膜。用X-射线衍射（XRD）和扫描电子显微镜（SEM）对其结构及形貌进行表征,发现先在Cu衬底上沉积一层Zn致密膜,更有利于在其表面上得到附着力强、形貌较好的ZnO纳米结构膜。系统考察了沉积温度和沉积时间等工艺参数对ZnO纳米结构的影响。结果表明,沉积温度和沉积时间对晶体结构和形貌有显著影响,通过对工艺进行适宜控制可以得到结晶性良好的六方纤锌矿型ZnO纳米结构膜。以罗丹明B为目标有机污染物,分析了ZnO膜的光催化性能,表明所制备的ZnO膜可以作为光催化剂,其光催化效率可达到72.4%。     

Properties and Morphology of TiN Films Deposited by Atomic Layer Deposition

In this study,TiN films were deposited on SiO2 substrates by Atomic Layer Deposition(ALD) using TiCl4and NH3 as precursors. Properties and morphology of the TiN films were characterized by different methods.Using Grazing Incidence X-Ray Diffraction(GIXRD),TiN films demonstrated polycrystalline structure with(111)preferred orientation. Film thickness was measured by Spectroscopic Ellipsometry(SE) and a stable growth rate of 0.0178 nm/cycle was reached after 500 deposition cycles,which was consistent with the essence of ALD as a surface-saturated self-limiting reaction. Film resistivity measured by a four-point probe continuously decreased with increasing deposition cycles until it reached the minimum value of 300μΩ cm at 5000 deposition cycles with a thickness of 87.04 nm. The surface roughness and morphology of the TiN films at different deposition cycles ranging from 50 to 400 were analyzed by Atomic Force Microscopy(AFM). The AFM results indicated that the initial film growth follows the Stranski-Krastanov mode.     

3D激光沉积增材制造TC4高应变率动态力学行为及本构关系研究

通过对3D激光沉积TC4在较宽温度（298~1 073 K）和应变率范围（0.001~5 000 s^-1）内的单轴压缩试验,系统研究了该材料的塑性流动行为,分析了材料的微观组织特性及其变形断裂微观机制.结果表明材料在压缩载荷下具有明显的应变率硬化和温度软化效应.在压缩加载条件下,材料的破坏模式为绝热剪切带的萌生和拓展,而初始缺陷成为诱导剪切带形成的主要原因.3D激光沉积TC4材料屈服强度与铸造TC4接近,略低于传统锻造TC4.文中基于位错动力学热激活理论建立了可以较好描述材料在不同温度不同应变率下的塑性流动行为物理概念的本构模型.     

硫脲加速和稳定化学沉积镍的机理

测定了硫脲对化学沉积镍的速度、析氢量、极化曲线和稳定电位的影响,并结合对沉积镍层的X射线光电子能谱(XPS)分析,探讨了硫脲对化学沉积镍过程的加速和稳定机理.     

无氢类金刚石膜的光致发光特性研究

使用脉冲激光沉积（PLD）技术制备了系列无氢类金刚石（DLC）薄膜,测量了样品的Raman光谱、光吸收和光致发光,研究了光致发光与制备条件的依赖关系。结果表明,这种薄膜是有少量sp^2键和sp^2键组成的非晶碳膜。薄膜的光学带隙在1．68～2.46eV,发光在可见光区呈宽带结构。沉积温度对类金刚石薄膜的结构和发光性质有较大影响。当沉积温度从室温升高至400℃时,sp^2团簇的长大使C原子的有序度增强,从而导致薄膜的光学带隙变窄,发光峰红移且半高宽变小。     

钛基Pbo2疏水电极的研究

提出了一种特别适用于憎水性有机物电解合成的疏水 Ｐｂ Ｏ２ 电极的制备方法,并讨论了制取此电极的各种工艺条件,测试了电极的一些性能．该电极较好地解决了以往以钛为基体的 Ｐｂ Ｏ２ 电极所存在的镀层与基体结合不牢、机械强度差,在用于有机合成时,电化学反应阻抗大,电流效率低,槽压高,能耗大等一系列问题     

包镍Al2O3颗粒的获得及其在复合材料制备中的应用

用自制的化学气相沉积装置在Ａｌ２Ｏ３颗粒表面获得了Ｎｉ涂层,并通过负压铸渗工艺获得了Ａｌ２Ｏ３颗粒／耐热钢基复合材料,考察了其高温磨料磨损特性,结果表明：Ｎｉ涂层能显著改善Ａｌ２Ｏ３与耐热钢的湿润性,从而解决了Ａｌ２Ｏ３颗粒在耐热钢液中均匀分散的难题,所得复合材料具有优良的高温磨料磨损抗力。