The migration of protons and deuterons parallel to the hexagonal c-axis of pure or Mg-doped material was studied by monitoring the infra-red absorption of OH- and OD- ions during annealing at temperatures of between 450 and 650C. The activation energies for the out-diffusion of protons and the in-diffusion of deuterons (figure 6) were found to be 1.1eV and 1eV, respectively. The data for D diffusion in the niobate could be described by:

LiNbO3:     D (cm2/s) = 0.041 exp[-0.96(eV)/kT]

LiNbO3-8mol%Mg:     D (cm2/s) = 0.020 exp[-0.98(eV)/kT]

L.Kovacs, K.Polgar, R.Capelletti, C.Mora: Physica Status Solidi A, 1990, 120[1], 97-104

Figure 6

Diffusivity of D in LiNbO3