基于Klarite芯片的表面增强拉曼散射特性研究

本文介绍了一种商用的表面增强拉曼芯片(Klarite),并对其表面形貌、拉曼活性进行了表征和测试分析.Klarite芯片由于独特的倒金字塔形设计使得其具有较好的拉曼活性、稳定性和重现性,为生命科学和分析化学研究提供了有力的研究工具.此外,我们对Klarite芯片在外电磁场作用下的表面电场分布进行了模拟,发现一个结构单元...     

Oxygen vacancy formation and migration in Sr- and Mg-doped LaGaO3: a density functional theory study

Oxygen vacancy formation and migration in La0.9Sr0.1Ga0.8Mg0.2O3-5 （LSGM） with various crystal symmetries （cubic, rhombohedral, orthorhombic, and monoclinic） are studied by employing first-principles calculations based on density functional theory （DFT）. It is shown that the cubic LSGM has the smallest band gap, oxygen vacancy formation energy, and migration barrier, while the other three structures give rise to much larger values for these quantities, implying the best oxygen ion conductivity of the cubic LSGM among the four crystal structures. In out calculations, one oxygen vacancy migration pathway is considered in the cubic and rhombohedral structures due to all the oxygen sites being equivalent in them, while two vacancy migration pathways with different migration barriers are found in the orthorhombic and monoclinic symmetries owing to the existence of nonequivalent O1 and 02 oxygen sites. The migration energies along the migration pathway linking the two 02 sites are obviously lower than those along the pathway linking the O1 and 02 sites. Considering the phase transitions at high temperatures, the results obtained in this paper can not only explain the experimentally observed different behaviours of the oxygen ionic conductivity of LSGM with different symmetries, but also predict the rational crystal structures of LSGM for solid oxide fuel cell applications.     

ZnO:Fe薄膜制备、光学与电学性质研究

用双靶磁控溅射设备制备了ZnO:Fe薄膜。分析了铁靶溅射功率对薄膜的光学及电学性质的影响。X射线衍射(XRD)和原子力显微镜(AFM)图像表明:ZnO:Fe薄膜为六角纤锌矿结构,且具有非常好的沿垂直于衬底的c轴择优取向。当铁靶功率小于250W时,沉积速率随铁靶功率的增加而增加。随着铁靶功率的增加,透射光谱的吸收边有微弱蓝移,透过率在可见光区超过75%。掺铁后薄膜的电阻率只有10-2Ω.cm,远小于纯氧化锌的电阻率。通过实验得到ZnO:Fe薄膜的最佳制备条件。     

负热膨胀材料研究进展

本文介绍了负热膨胀材料的制备技术、结构、性能、应用及热缩机理研究的主要进展。分析了负热膨胀材料合成及其应用中存在的主要问题,讨论了刚性单元模模型及其局限性,给出了热缩机理理论和实验特别是第一性原理声子谱计算和拉曼光谱研究的最新进展、存在问题及发展趋势。指出了负热膨胀材料研究中应重点解决的一些重要问题。     

表面增强喇曼散射的应用

本文概述了表面增强喇曼散射在以下几个领域中的应用:催化和热分解过程中的中间产物和产物探测,及这些产物的热稳定性分析;金属腐蚀问题中,各种防腐剂的防腐蚀性能分析,及表面络合物研究;生物分子的构型变化、成分;界面行为的研究;痕量分析;光电器件(半导体光电化学器件,光电倍增管等)表面特性及组分分析;固态材料表面化学性质和形态结构信息的获得,等等。     

碳纳米管拉曼光谱研究新进展

本文介绍碳纳米管拉曼光谱研究的最新进展。重点介绍金属性和半导体性碳纳米管的共振拉曼效应、表面增强拉曼效应和偏振拉曼效应。同时也介绍了碳纳米管的温度效应、压力效应和杨氏模量的拉曼光谱研究     

结晶紫与卤素或卤酸根离子共吸附的近红外表面增强喇曼散射

采用近红外激光（１０６４ｎｍ）激发和扫描式双光栅单色仪研究了卤素、卤酸根离子及吡啶对结晶紫近红外表面增强喇曼散射光谱（ＮＩＲ－ＳＥＲＳ）的影响．揭示了这些离子（或分子）与结晶紫及银表面的相互作用．Ｃｌ－、Ｂｒ－、Ｉ－、ＢｒＯ－３离子及吡啶均能引起结晶紫ＮＩＲ－ＳＥＲＳ的明显增强，而ＣｌＯ－３和ＩＯ－３离子则不能．观察到ＮＩＲ－ＳＥＲＳ中化学增强的直接证据，并估算了化学增强因子．Ｃｌ－、Ｂｒ－、Ｉ－和ＢｒＯ－３离子引起结晶紫ＮＩＲ－ＳＥＲＳ的化学增强因子分别约为４９、７７、１５和３６．     

Effects of Al particles and thin layer on thermal expansion and conductivity of Al-Y_2Mo_3O_(12) cermets

Low thermal expansion composites are difficult to obtain by using Al with larger positive thermal expansion coefficient(TEC) and the materials with smaller negative TECs. In this investigation, Y_2Mo_3O_(12) with larger negative TEC is used to combine with Al to obtain a low thermal expansion composite with high conductivity. The TEC of Al is reduced by 19%for a ratio Al:Y_2Mo_3O_(12) of 0.3118. When the mass ratio of Al:Y_2Mo_3O_(12) increases to 2.0000, the conductivity of the composite increases so much that a transformation from capacitance to pure resistance appears. The results suggest that Y_2Mo_3O_(12) plays a dominant role in the composite for low content of Al(presenting isolate particles), while the content of Al increases enough to contact each other, the composite presents mainly the property of Al. For the effect of high content Al, it is considered that Al is squeezed out of the cermets during the uniaxial pressure process to form a thin layer on the surface.     

Oxygen ion conductivity of La_(0.8)Sr_(0.2)Ga_(0.83)Mg_(0.17-x)Co_xO_(3-δ) synthesized by laser rapid solidification

Materials La0.8Sr0.2Ga0.83Mg0.17-xCoxO3-δ with x = 0, 0.05, 0.085, 0.10, and 0.15 are synthesized by laser rapid solidification. It is shown that the samples prepared by laser rapid solidification give rise to unique spear-like or leaf-like microstructures which are orderly arranged and densely packed. Their electrical properties each show a general dependence of the Co content and the total conductivities of La 0.8 Sr 0.2 Ga 0.83 Mg 0.085 Co 0.085 O 3-δ prepared by laser rapid solidification are measured to be 0.067, 0.124, and 0.202 S·cm -1 at 600, 700, and 800℃, respectively, which are much higher than by conventional solid state reactions. Moreover, the electrical conductivities each as a function of the oxygen partial pressure are also measured. It is shown that the samples with the Co content values ≤ 8.5 mol% each exhibit basically ionic conduction while those for Co content values ≥ 10 mol % each show ionic mixed electronic conduction under oxygen partial pressures from 10 -16 atm (1 atm = 1.01325×10 5 Pa) to 0.98 atm. The improved ionic conductivity of La 0.8 Sr 0.2 Ga 0.83 Mg 0.085 Co 0.085 O 3-δ prepared by laser rapid solidification compared with by solid state reactions is attributed to the unique microstructure of the sample generated during laser rapid solidification.