Li‐Rich Vapor Transport Equilibration Temperature Dependence of Surface Composition of Initially Congruent LiNbO3 Crystal
The influence of Li‐rich vapor transport equilibration (VTE) on surface Li2O‐content of 1‐mm‐thick,
congruent X‐, and Z‐cut LiNbO3 crystal plates was studied against the VTE temperature. The VTE‐induced surface Li2O‐content
increase was evaluated from measured birefringence. The results show that the increase follows the traditional Arrhenius law with a surface Li2O‐content alteration constant (614 ± 136)/(91 ± 10) mol%
and an activation energy (0.76 ± 0.05)/(0.53 ± 0.03) eV for the X/Z‐cut plate. An empirical expression that correlates the VTE‐induced surface Li2O‐content
alteration with both the VTE temperature and duration is presented. The expression is useful for producing a near‐stoichiometric LiNbO3 plate with the desired surface Li2O‐content
via balancing the VTE temperature and duration.