Crystal Structure of Proton-Exchanged Layers on Single Crystals of LiNbO3

The crystal structure of proton-exchanged layers on single-crystal LiNbO3 was analyzed using the X-ray precession method. It was found that the layers were of single crystals, and that the structures varied depending on the orientation of the LiNbO3 wafers: on the (014̄) wafers, an orthorhombic phase appeared, whereas a hexagonal phase was obtained on the Z-cut (001) wafers. This suggests that the exchange reaction proceeds topotactically: protons replace Li ions with small changes in the atomic framework of oxygen and niobium.