Abstract: Lithium diffusion in low MgO-doped LiNbO3 crystals was investigated under Li rich environment at high temperature.The vapor transport equilibration (VTE) method was used to prepare 1 mol; MgO-doped LiNbO3 (Mg1LN) crystals with widely varying diffusion-limited Li2O content profiles.The thermal analyzer was used to measure the Curie temperature of samples.Mg1LN polycrystalline powders with different Li2O content were prepared to fit the correlation between the Li2O content and Curie temperature.A Boltzmann-Matano mathematical method was used to solve the diffusion equation.Results show that at the temperature of 1100 ℃, the diffusivity of Li+ increases from 3.2×10-9 cm2/s ([Li2O] is 48.7mol;) to 13.0×10-9 cm2/s ([Li2O] is 49.56mol;), and the diffusivity increases nearly three times at 1145 ℃ than that at 1100 ℃.It can be concluded that increasing the diffusion temperature reasonably is an effective way to improve the efficiency for preparing stoichiometric low MgO-doped LiNbO3 crystals by VTE method.

Key words: Lithium diffusion in low MgO-doped LiNbO3 crystals was investigated under Li rich environment at high temperature.The vapor transport equilibration (VTE) method was used to prepare 1 mol; MgO-doped LiNbO3 (Mg1LN) crystals with widely varying diffusion-limited Li2O content profiles.The thermal analyzer was used to measure the Curie temperature of samples.Mg1LN polycrystalline powders with different Li2O content were prepared to fit the correlation between the Li2O content and Curie temperature.A Boltzmann-Matano mathematical method was used to solve the diffusion equation.Results show that at the temperature of 1100 ℃, the diffusivity of Li+ increases from 3.2×10-9 cm2/s ([Li2O] is 48.7mol;) to 13.0×10-9 cm2/s ([Li2O] is 49.56mol;), and the diffusivity increases nearly three times at 1145 ℃ than that at 1100 ℃.It can be concluded that increasing the diffusion temperature reasonably is an effective way to improve the efficiency for preparing stoichiometric low MgO-doped LiNbO3 crystals by VTE method.