First principle study on the elastic and thermodynamic properties of TiB2 crystal under high temperature

This paper predicts the elastic and thermodynamic characteristics of TiB2 crystal through the method of density functional theory within the generalized gradient approximation(GGA).The five independent elastic constants(Cij),the bulk modulus(B0),the dependence of bulk modulus(B0) on temperature T and pressure P and the coefficient of thermal expansion(αL) at various temperatures have been evaluated and discussed.According to calculation,the bulk modulus will increase with increasing pressure while decrease with the increasing temperature.The coefficient of thermal expansion is consistent with the famous Gruneisen’s law when the temperature is not too high.The obtained results agree well with the experimental and other theoretical results.     

六硼化铕亚微米管的电子场发射性能(英文)

以铕(Eu)粉末和三氯化硼(BCl3)作为前驱体,用简单的化学气相沉积方法制备了六硼化铕(EuB6)亚微米管。用XRD,SEM拉曼光谱,和TEM来表征EuB6微米管的形貌和晶体结构。场发射测试结果表明:根据F-N公式,场发射电流和电场之间在不同的阶段分别满足直线关系。     

Tunable broadband metamaterial absorber consisting of ferrite slabs and a copper wire

A tunable broadband metamaterial absorber is demonstrated at microwave frequencies in this paper.The metamaterial absorber is composed of ferrite slabs with large resonance beamwidths and a copper wire.The theoretical analysis for the effective media parameters is presented to show the mechanism for achieving the perfect absorptivity characteristic.The numerical results of transmission,reflectance,and absorptivity indicate that the metamaterial absorber exhibits a near perfect impedance-match to free space and a high absorptivity of 98.2% for one layer and 99.97% for two layers at 9.9 GHz.The bandwidth with the absorptivity above 90% is about 2.3 GHz.Moreover,the absorption band can be shifted linearly in a wide frequency range by adjusting the magnetic bias.This metamaterial absorber opens a way to prepare perfectly matched layers for engineering applications.     

教·学·做的有效整合——高中数学“轻负高质”的一些尝试

新课程标准的有效施行,不仅需要努力,更需要智慧.我们应致力把新课程理念贯穿于教学的全过程,在正确的导向引领下注重教学策略.让我们的理念和教学行为在新旧课程的融合中改善,在改善中精致,在精致中创新,在创新中实现轻负高质教学工作就时间段的分类上来讲可以分为学生学习前、学习中、学习后三个环节,就教学行为上来讲,可以分为教师前期备课、教师指导下学生的学习、学生课后的学习三个方面.要实施轻负高质的教学,当然要从以上三个方面在三个环节中的表现抓起.     

石墨烯的制备、表征及其在透明导电膜中的应用

近年来,石墨烯因其优异的电学和光学等特性,越来越受到人们的广泛关注。研究人员应用多种方法来合成石墨烯并且探讨其潜在的应用价值。本文首先简要介绍了石墨烯的结构及其基本的物理性质,并简单回顾了石墨烯的合成方法和表征手段。在此基础上,讨论了石墨烯/银复合薄膜在透明导电膜中的应用,并详细介绍了我们在该领域的研究成果。用化学气相沉积法（CVD）和多羟基法分别制备了双层石墨烯及银纳米线,成功合成了石墨烯/银复合薄膜,结果表明复合薄膜的方块电阻可降低至26 Ω·□-1,展示了其在光电器件上广泛的应用前景。     

Na_3AlF_6-AlF_3熔盐中Ti(Ⅳ)的阴极还原机理

应用循环伏安法和计时电位法研究了在990℃下Na3AlF6-AlF3熔盐中,TiO2钨丝电极上的阴极还原机理.实验表明,Ti(Ⅳ)电沉积过程分两步进行:即首先是Ti(Ⅳ)还原为Ti(Ⅱ),然后Ti(Ⅱ)再还原为金属钛,可表示为:Ti(Ⅳ)→Ti(Ⅱ)→Ti.