锂离子外扩散对扩镁铌酸锂表层结晶特性的影响

INFLUENCE OF LITHIUM ION OUTDIFFUSION ON THE CRYSTALLINITY OF MAGNESIUM DIFFUSED LITHIUM NIOBATE SURFACE LAYER

利用常规X射线衍射和掠入射X射线衍射对在空气中进行镁离子内扩散的扩镁铌酸锂单晶表层的富氧化镁层特性进行了研究,揭示出镁离子内扩散初期随着体内锂离子的外扩散,首先在富氧化镁层形成Li_3Mg_2NbO_6和Mg_4Nb_2O_9的化合物结构,Li_3Mg_2NbO_6出现在富氧化镁的内表层,而Mg_4Nb_2O_9在富氧化镁层形成一均匀层。随着镁离子内扩散的继续,Li_3Mg_2NbO_6和Mg_4)Nb_2O_9的结构相继消失,又出现LiNb_3O_8的物相结构。同时还对这些扩镁铌酸锂的表面进行了扫描电子显微镜观察,揭示出了多晶形貌和这些表层相的分解和消失过程。

With the conventional X-ray diffraction and grazing-incidence X-ray diffraction. We have investigated the MgO-rich layer characteristics in the magnesium diffused lithium niobate single crystal, when the magnesium-ion indiffusion process in the layer is carried out in atmosphere. It is found that the MgO-rich layer exhibits the crystal structure of Li3Mg2NbO6 and Mg4Nb2O9, when indiffusion time for magnesium-ion is short. these aspects indicate that Li3Mg2NbO6 is in the subsurface layer of MgO-rich layer and Mg4Nb2O9 forms an uniform layer in the MgO-rich layer. When further increasing diffusion time the lithium-ion outdiffusion from the bulk of lithium niobate become prominent and Li3Mg2NbO6 and Mg4Nb2O9 compounds disappear in succession, and LiNb3O8 compound structure appears consequentially. It is observed by scanning electron microscopy that the surface of magnesium diffused lithium niobate indicates a multicrystal structure, the decomposing and disappearing processes of these surface layer compounds are also revealed