Abstract
Several near-stoichiometric lithium niobate (LiNbO
) plates for Periodically poled lithium niobate (PPLN) were prepared by vapor transport equilibrium (VTE) technique. External electric field poling was carried out on these samples. A linear dependence of the switching field on the concentration of anti-site niobium ions was observed. This linear relationship was explained by a two-dimensional model based on the dynamics of domain wall. In this model, the bowing of domain wall and the pinning role of anti-site niobium ions to the movement of domain wall were considered. The pinning-depinning transition of domain wall was attributed to the movement of anti-site niobium ions through the oxygen plane, which is due to the change of domain environment round anti-site niobium ions . A parameter of , denoting the ratio between the negative and positive domains round anti-site niobium ions , was introduced. The interaction between anti-site niobium ions and rounding domain environment was analyzed associating with the parameter . With the help of the shell-model theory, the force needed for anti-site niobium ions to pass through the oxygen plant was given as 1.696×10
N and the critical c corresponding to domain reversal was calculated to be about 67° in degree. Using the fitting result of experiment data, the domain wall energy per unit area for LiNbO
was also roughly calculated as 0.41 J/m
.