Lithium Diffusion in Lithium Niobate Crystals with Different Initial Li 2 O Content at High Temperature

Lithium diffusion in lithium niobate crystals with different initial Li 2 O content ( C initial ) was investigated under Li‐rich environment at 1100°C. Lithium niobate crystals with widely varying diffusion‐limited Li 2 O content profiles were prepared through the vapor transport equilibration (VTE) technique using congruent lithium niobate crystals with different C initial , and the profiles were measured through Curie temperature by a thermal analyzer. A Boltzmann‐Matano analysis was employed to those profiles to estimate the Li + diffusivity as a function of Li 2 O content in lithium niobate crystals. A trigonometric function method was applied to those profiles to correlate diffusion time and Li 2 O content. The results show that at the same composition of lithium niobate crystals after diffusing treatment, the less the C initial, the larger the Li + diffusivity. The relation between diffusion time and Li 2 O content of the samples which have different C initial and thickness was derived. Based upon the Boltzmann‐Matano result, diffusion time can be estimated easily from the relation. It is concluded that increasing C initial contributes to shorten the diffusion time for preparing near‐stoichiometric lithium niobate crystals through the VTE technique, especially for thick crystal wafers.