Influence of lithium - Ion outdiffusion on the crystallinity of magnesium diffused lithium niobate surface layer

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.