The effect of annealing atmosphere on structure characteristics of magnesium diffused lithium niobate single crystal substrates

MgO is evaporated on lithium niobate (LiNbO3) single crystal substrates and is later annealed in air. The structure evolution of the MgO-rich layer as the Mg ion diffuses by means of annealing is investigated by conventional X-ray diffraction, glancing-incidence X-ray diffraction, and scanning elect ron microscopy. It is found that Li3Mg2NbO6 and Mg4Nb2O9 are first formed a nd followed by the formation of a uniform layer of Mg4Nb2O9 in the MgO rich layer. Meanwhile, Li3Mg2NbO6 is also formed in the MgO-rich subsurface lay er. With the completeness of Mg-ion indiffusion, Li3Mg2NbO6 and Mg4Nb2O9 Co mpounds disappear one after another, and LiNb3O8 finally appears in the dif fused magnesium layer.