Short range order transformation and magnetostriction of Fes3Ga17 ribbons

The relationship between magnetostriction and structure of melt-spun Fes3Ga17 ribbons are investigated by XRD and M5ssbauer spectrum technique （MS）. As the heat-treatment temperature increases from 650℃ to 800℃, the magnetostriction coefficient of Fes3Ga17 ribbon first increases and then decreases. The largest magnetostriction coeiffcient （-578.4 ppm） is achieved in those specimens quenched at 750oc. According to the XRD and MSssbauer spectrum anal- ysis, a small quantity of DO3 phase is precipitated in Fe83Ga17 ribbons when quenched from 650℃ and the DO3 phase is gradually transformed into B2-1ike phase if quenched at higher temperature. However, both DO3 and B2-1ike phases disappear when the temperature increases up to 800℃. From this point of view, B2-1ike phase might be beneficial to the enhancement of magnetostrictive properties of melt-spun ribbons.     

草酸铕颗粒微米层状颗粒的合成及其光学性能

在室温条件下, 以柠檬酸钠为辅助剂, 通过简单沉淀法合成了草酸铕Eu₂(C₂O₄)₃·10H₂O微米层状颗粒. 应用X射线衍射、X射线电子能谱、场发射扫描电子显微镜、光致发光光谱对Eu₂(C₂O₄)₃·10H₂O结构与性能进行了表征. 讨论了草酸铕微米层状颗粒可能的形成机理.     

Fabrication of silicon microwire arrays for?photovoltaic?applications

A?novel method of combining photolithography, wet chemical etching and oxidation process was proposed to fabricate large area of silicon microwire (SiMW) arrays. The dimensions of the SiMWs can be easily controlled by photomask and etching conditions. Solar cells based on the heterojunction between SiMW and double-walled carbon nanotubes (DWNTs) were constructed. The initial test on the DWNT/SiMW shows efficiency (??) of?0.59%. By adding a few drops of HBr/B₂ electrolyte, the efficiency was improved to 1.96% with J _sc=19.2?mA/cm² and V _oc=0.35?V, FF=29.2%, showing the potential of SiMWs in photovoltaic applications.     

Widely tunable fourth harmonic generation of a Ti:sapphire laser based on RBBF crystal

Fourth harmonic generation of a tunable Ti:sapphire laser with a repetition rate of 80?MHz and pulse duration ??150 fs has been realized in a single pass with an RbBe₂BO₃F₂ crystal for the first time. A high average power was obtained which was tunable throughout a wide range from 180 to 232.5?nm. The output power over the whole range exceeded 2?mW, the highest being 43.3?mW at 202.5?nm. Moreover, deep-ultraviolet output with powers above 75?mW was obtained at 193.5 and 200?nm under a stronger focusing condition. This is the first attempt at the generation of tunable deep-ultraviolet light without using a KBBF crystal, which is very difficult to grow due to its strong layering tendency, and our attempt may provide new opportunities for the development of all-solid-state deep-ultraviolet coherent light sources.     

Numerical Modeling on Heat Transport Across Stochastic Magnetic Field

The heat diffusion across the stochastic magnetic field is studied numerically. The stochastic field is generated by the overlap of two magnetic islands. The parameter w/w_c, is found tobe an important parameter in charactering the transport, where w is the magnetic island width, and w_c is the critical island width for flattening the electron temperature across an island. For w/w_c < 1, the enhanced radial heat diffusivity χ_r is proportional to the parallel heat diffusivity χ_∥, and the heat transport is dominated by the additive effect of individual islands. For w/w_c > 3, χ_r is also proportional to χ_∥ and the additional degradation of the energy confinement due to stochastic magnetic field becomes apparent. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Discharge Characteristics of Microwave Plasma in Ethanol Solution

An apparatus was designed for generating plasma in ethanol solution. The plasma was generated on the top of the electrode by applying microwave radiation of 2.45 GHz. The results showed that ignition power decreased with increasing temperature of ethanol solution. However, ignition power increased with increasing pressure and point electrode radius of curvature. Plasma and bubbles were generated periodically in the same manner. The electron temperature of the plasma increased with increasing power, while it decreased with increasing pressure. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

石墨烯：打开二维材料之门——评2010 年诺贝尔物理学奖

 维度是指能够完整描述一个对象所必需的独立参数的个数。例如, 我们所处的空间是三维的, 因为描述这个空间需要“上下、前后、左右”三个独立方向。维度的概念被广泛应用于数学、物理学和哲学等诸多领域中。在材料研究领域, 人们希望得到维度意义完整的材料体系。长期以来, 对于碳材料家族, 只有金刚石和石墨这两种三维结构为人类所知。1985 年, 美国和英国的三位科学家哈瑞·克罗托（Harry Kroto）、理查德·斯莫利（RichardSmalley）和罗伯特·科尔（Robert Curl）率先发现了C₆₀。C₆₀ 是由60 个碳原子组成20 个六边形和12个五边形构成的足球状碳单质, 属于零维结构碳材料。C₆₀ 其实是众多球状和椭球状碳分子大家族中的一员, 我们现在称这个大家族为“富勒烯”。富勒烯的发现第一次从维度概念上丰富了碳材料。1991年, 日本科学家饭岛澄男（Sumio Iijima）试图使用石墨电弧放电法来制备富勒烯, 当他在高分辨透射电子显微镜观察产物时意外地发现了一种管状的碳单质--碳纳米管。碳纳米管的出现再一次将碳材料的维度扩展到一维空间。当零维、一维和三维的碳材料被成功合成后, 揭示已知维度碳单质的性能和应用并探寻碳的二维晶体结构, 成为材料科学领域的两个热点。