Dynamic Simulation of Vapor Transport Equilibration in Congruent LiNbO3 Crystal

Vapor transport equilibration (VTE) in a congruent lithium niobate (LiNbO 3 ) plate is modeled using the implicit finite difference method, and Li-diffusion at 1100 °C in both Z -cut and X -cut plates with thicknesses from 0.5 to 3 mm is simulated for VTE duration up to 450 h. Li-diffusivity at 1100 °C was determined experimentally based upon secondary-ion-mass spectrometry (SIMS) analysis. A good agreement of numerical results with SIMS results or optical absorption edge measurement results confirms the accuracy of the Li-diffusivity and the validity of the VTE model proposed and the numerical method employed. The mutual influence problem of two VTE processes from the top and the bottom surfaces of the plate and the VTE duration needed to fully VTE-treat a plate are discussed in relation to the crystal's cut and thickness. The VTE duration dependence on the mean Li/Nb ratio within a 20 μm depth is studied.