改进验电器的设计及其应用示例

基于电场中带电体受力方向与所带电荷的类别有关改进了传统的验电器,带电指针可以左右偏转,直接区分物体带电类别;通过改变外接电压源的电压改变电场,调节验电器的量程.改进验电器可以用来探究摩擦起电、静电感应起电和静电平衡条件下导体带电的规律.     

Negative Thermal Expansion and Spontaneous Magnetostriction of Nd2Fe16.5Cr0.5 Compound

The structural,thermal expansion,and magnetic properties of the Nc/2^16.5^0.5 compound are investigated by means of x-ray diffraction and magnetization measurements.The Nd2^616.560.5 compound has a rhombohedral Th2Znn-type structure.There exists a small negative thermal expansion resulting from a spontaneous magnetostriction in the magnetic state of the^2^16.5 Cr0.5 compound.The average thermal expansion coefficient is-1.06×10^6/K in a temperature range 299-394 K.The spontaneous magnetostrictive deformation and the Curie temperature are discussed.     

机械纵波的观察与波速测量实验的设计构思

为了进一步丰富大学物理实验课的教学内容,针对机械波特别是机械纵波实验较少的情况,我们设计了一种一维弹性介质链来演示机械纵波在弹性介质中的产生和传播过程,并验证机械波波速与频率无关,只决定于介质的性质。具体为采用轻质小弹簧连接的塑料小球链模拟质元之间的弹性力和一维弹性介质质元,采用带电小球在交变电场作用下的振动模拟波源的办法,设计了一个可观察机械纵波并测量波速的实验。这个实验既可以作为大学物理实验课的教学内容,也可以作为中学物理实验的演示实验,有助于学生直观形象地理解机械波的产生和机械波在弹性介质中的传播机理。     

飞秒激光诱导图案独立显示研究

介绍了采用中心波长为800nm的飞秒激光在不锈钢(316L)表面诱导产生独立显示图案的研究。结果表明,当扫描速率为15mm/s,扫描行距为20μm,能量密度为1.1J/cm2时,飞秒激光能够在不锈钢表面形成均匀的周期为540nm的亚波长条纹结构。利用条纹结构的方向与激光光波偏振方向严格垂直的特性,通过改变激光偏振,可以在金属表面形成不同方向的条纹图案。在照明白光的辐照下,改变样品的方位角,形成的图案能够以彩色方式显示出来。此外,对使图案彩色显示的坐标区域与图案色彩能够覆盖的可见光谱范围进行了研究,并对其可能的应用进行分析。     

Negative Thermal Expansion of the Dy_2Fe_(16)Cr Compound

Structural, thermal expansion, and magnetic properties of the Dy_2Fe_(16)Cr compound are investigated by means of x-ray diffraction and magnetization measurements. The Dy_2Fe_(16)Cr compound has a hexagonal Th_2Ni_(17)-type structure. There exists a negative thermal expansion resulting from a strong spontaneous magnetostriction in the magnetic state of the Dy_2Fe_(16)Cr compound. The average thermal expansion coefficient is-0.794 × 10~(-5)/K in the temperature range 292–407 K. The spontaneous magnetostrictive deformation and the Curie temperature are discussed.     

Microstructure and lateral conductivity control of hydrogenated nanocrystalline silicon oxide and its application in a-Si:H/a-SiGe:H tandem solar cells

Phosphorous-doped hydrogenated nanocrystalline silicon oxide(n-nc-SiO_x:H) films are prepared via radio frequency plasma enhanced chemical vapor deposition(RF-PECVD). Increasing deposition power during n-nc-SiO_x:H film growth process can enhance the formation of nanocrystalline and obtain a uniform microstructure of n-nc-SiO_x:H film. In addition,in 20 s interval before increasing the deposition power, high density small grains are formed in amorphous SiO_x matrix with higher crystalline volume fraction(I_c) and have a lower lateral conductivity. This uniform microstructure indicates that the higher Ic can leads to better vertical conductivity, lower refractive index, wider optical band-gap. It improves the back reflection in a-Si:H/a-SiGe:H tandem solar cells acting as an n-nc-SiO_x:H back reflector prepared by the gradient power during deposition. Compared with the sample with SiO_x back reflector, with a constant power used in deposition process,the sample with gradient power SiO_x back reflector can enhance the total short-circuit current density(Jsc) and the initial efficiency of a-Si:H/a-SiGe:H tandem solar cells by 8.3% and 15.5%, respectively.