Co^3＋—modified Surface of LiMn2O4 Spinel for its Improvementof Electrochemical Properties

Cobalt was used to modify the surface of spinel LiMn2O4 by a solution technique to produce Co^3 -modified surface material (COMSM). Cobalt was only doped into the surface of LiMn2O4 spinel. XPS(X-ray photoelectron spectroscopy) analysis confirms the valence state of Co^3 . COMSM has stable spinel structure and can prevent active materials from the corrosion of electrolyte. The ICP(inductively coupled plasma) determination of the spinel dissolution in electrolyte showed the content of Mn dissolved from COMSM was smaller than that from the pure spinel. AC impedance patterns show that the charge-transfer resistance (Rct) for COMSM is smaller than that for pure spinel. The particles of COMSM are bigger in size than those of pure spinel according to the micrographs of SEM(scanning electron microscopy). The determinations of the electrochemical characterization show that COMSM has both good cycling performance and high initial capacity of 124.1 mA/h at an average capacity loss of 0.19 mAh/g per cycle.     

光纤激光器及其在通信中的应用

光纤激光器作为第三代激光器的代表，在光纤通信中发挥着非常重要的作用。本文介绍了光纤激光器的工作机理及优势，阐述了光纤激光器技术在光通信中的主要应用及其未来发展方向。     

液相外延Co—YIG薄膜的制备及光吸收谱分析

采用液相外延法在钆镓石榴石（ＧＧＧ）基片的（１１１）晶面上生长出了掺Ｃｏ钇铁石榴石薄膜，研究了生长温度和基片转速对掺Ｃｏ量的影响，测量和分析Ｃｏ－ＹＩＧ薄膜样品在０．５—１．８μｍ波长范围的光吸收谱，发现Ｃｏ－ＹＩＧ薄膜中八面体位和四面体位的Ｃｏ３十离子在０．６μｍ和１．３１μｍ波长处的晶场跃迁对光吸收有贡献．     

掺杂的MgB2超导体中Fe和Co的局域环境

由于MgB2具有39K的超导转变温度，因此使它成为另一类别的高温超导体的新成员，它可以用做穆斯堡尔谱仪这种化学探测技术的激发靶。穆斯堡尔谱仪可以用来探测固体的电子特性，震动特性和磁特性。如果所研究的材料中不含穆斯堡尔激发元素，那末就需要掺杂，最常用的是Fe。用穆斯堡尔谱仪对高Tc铜氧化物超导体虽已进行过广泛的研究，但是由于这种铜氧化物超导体结构的复杂性，使穆斯堡尔谱的解释变得非常困难。而MgB2仅含有两种元素，因此仅有两个可能的代位位置。匈牙利科学院结构化学核技术研究所最近用掺杂Fe和Co的MgB2超导体研究了掺…     

单台固定的激光晶体发射出红、绿、蓝色光

含有单个活性增益材料的固体激光器同步产生了红、绿、蓝色光，这种器件对于全彩色成像系统是非常有价值的．具有特色的是，该RGB激光是由激光棒和非线性晶体的复杂组合而实现的．单晶RGB激光器的一个样机已由法国Claude Bernard-Lyon大学和中国科学院开发出来，它是由基于钕掺杂的四硼酸钆铝晶体(NGAB)制作的．     

有机掺杂体系中的Foerster能量传递及其在电致发光中的应用

给体的光致发光量子效率、受体的消光系数及给体的发射谱与受体的吸收光谱的重叠程度，这3个因素对给体与受体间的能量传递效率有重要影响，这对于扩大材料的选择范围，实现有机电致发光的全色显示有重要启示。研究发现在Alq3中掺杂DCM制得的器件很好地满足了这3个条件。本文从Foerster能量传递的3个影响因素出发，对Alq3／DCM、TPD／Alq3等不同掺杂体系的光致发光、电致发光特性和能量传递效率等进行了讨论。     

Experimental investigation of the normal spectral emissivity and other thermophysical properties of pulse-heated Ni-Ti and Au-Ni alloys into the liquid phase

1. Introduction Metal working industry needs accurate thermo- physical properties of liquid metals and alloys as input data for different simulation routines to im- prove the performance of their products. Within this paper we continue the systematic investigation of the dependence of emissivity of binary alloys on the relative concentration of the constituent elements (for a previous paper see [1]). 2. Experimental method A fast ohmic pulse heating technique is applied to heat metallic wire-s…