A MATHEMATICAL-MODEL FOR TI DIFFUSION IN LINBO(3)

The diffusion of titanium in crystalline lithium niobate is studied wi thin the framework of the Nernst-Planck theory for ionic diffusion. Un der this conceptualization, a concentration-dependent diffusivity emer ges naturally from the mathematical model as a direct consequence of t he electric field induced by ion dislocation in the lattice. Numerical simulations of the one-dimensional case show strong evidence of enhan ced diffusive transport of mass. This might explain the anomalous late ral penetration of Ti in LiNbO3 which has been observed in previous ex periments.