镁离子内扩散铌酸锂研究(Ⅰ)——电子探针显微分析表征

A STUDY OF DIFFUSION OF Mg ION INTO LITHIUM N1OBATE (I)——CHARACTERIZATION BY ELECTRON PROBE MICROANALYSIS (EPMA)

对y切铌酸锂单晶基片镁离子内扩散后,镁的扩散层经电子探针显微分析(EPMA)表明,随着扩散深度镁离子浓度只有近似半抛物形分布,由此得到镁激活能为221kJ·mol^(-1)。探索性地分析了锂外扩散的机理,并提出了一种抑制锂外扩散的方法。对镁离子浓度分布进行了理论模拟,其结果基本上与实验符合。文中所得结果可用于铌酸锂单晶光纤芯-包层波导结构的实现,经选择适当参数(扩散温度、扩散时间、MgO膜厚度、晶纤直径)可望达到低次模传输。

After diffusion of Mg ion into the y-cut lithium niobate single crystal substrate plate, by using EPMA, it is shown that in the diffusion layer the Mg ion concen-tration distribution over diffusion depth follows approximately a half-parabolic law, from which an activation energy for Mg diffusion can be deduced as 221 kJ*-* mol^(-1). The mechamism of outward diffusion of Li ion is analyzed tentatively, and a method for suppressing such a diffusion is suggested. A theoretical simulation is carried out for Mg ion concentration distribution, the result agrees reasonably with the experiment. The results of the present work can be used in realizing the fab-rication of core-cladding wave guide structure of lithium niobate single crystal fiber. And by selecting suitable parameters, such as diffusion temperature, diffusion time, MgO film thickness and crystal fiber diameter, the low order modes transmission can be achiered.