镁离子内扩散铌酸锂研究(Ⅱ)—— X射线衍射和扫描电子显微镜表征

对不同扩散条件的铌酸锂单晶基片进行了X射线衍射分析(XRD)和扫描电子显微镜观察(SEM)。结果表明,在扩散表面富镁层出现一新相结构,可能是由Li-Mg-Nb-O组成的三元系相结构,这一新相被认为是镁离子内扩散的真正扩散源。并对晶格发生畸变、镁离子内扩散机理以及镁的扩散层折射率变化机理进行了分析和讨论。 关键词：     

退火a—Ge／Pb叠层膜的扩散机制与电阻率的反常行为

研究了a-Ge/Pb叠层膜不同温度下退火的行为,得到:PB诱导a-Ge晶化;发现a-Ge/Pb叠层膜在退火互扩散过程中存在两种扩散机制;对a-Ge/Pb为200nm/100nm的叠层膜,在退火互扩散中择优取向的Pb膜出现重新结晶。解释了退火过程中叠层膜电阻率的反常行为。     

Study on a Cross Diffusion Parabolic System

This paper considers a kind of strongly coupled cross diffusion parabolic system,which can be usedas the multi-dimensional Lyumkis energy transport model in semiconductor science.The global existence andlarge time behavior are obtained for smooth solution to the initial boundary value problem.When the initialdata are a small perturbation of an isothermal stationary solution,the smooth solution of the problem under theinsulating boundary condition,converges to that stationary solution exponentially fast as time goes to infinity.     

THE LARGE TIME BEHAVIOR OF SPECTRAL APPROXIMATION FOR A CLASS OF PSEUDOPARABOLIC VISCOUS DIFFUSION EQUATION

The asymptotic behavior of the solutions to a class of pseudoparabolic viscous diffusion equation with periodic initial condition is studied by using the spectral method. The semidiscrete Fourier approximate solution of the problem is constructed and the error estiation between spectral approximate solution and exact solution on large time is also obtained. The existence of the approximate attractor AN and the upper semicontinuity d(AN,A)→0 are proved.     

线性复值随机跳跃——扩散方程隐Miltein格式的渐近稳定性

给出了线性复值随机跳跃－扩散方程隐Ｍｉｌｔｅｉｎ格式的渐近均方的必要条件，并揭示了离散步长的稳定区域与格式隐性之间的关系。     

在局部区域上的奇摄动反应扩散方程初始边值问题

本文是讨论一类在局部区域上的奇摄动反应扩散初始边值问题.利用算子理论和 不动点原理,得到了相应问题解的存在性和唯一性.     

非线性时滞反应扩散方程组的奇摄动

本文研究了一类奇摄动非线性时滞反应扩散方程组,利用微分不等式方法,得到了解的一致有效的渐近展开式.     

化学位移各向导性对半整数自旋四极核的2D NMR章动的影响

考察了化学位移各向异性对半整数自旋四极核2D NMR章动的影响.用数值方法对2D NMR章动实验的演化期的Hamiltonian矩阵进行对角化,然后用帐篷法进行粉末平均,获得了自旋为I=3/2、5/2、7/2和9/2的四极核在不同化学位移各向异性下的2D NMR章动谱.实验结果与理论计算符合较好.