The H profiles in proton-exchanged layers of z-cut samples were measured by means of secondary ion mass spectrometry after annealing at 400C for times which ranged from 360s to 3h. In order to fit the measured H profiles, it was necessary to use 2 separate Gaussian diffusion profiles. These were attributed to more slowly diffusing substitutional H on Li sites, and more rapidly diffusing interstitial H. At 400C, analysis of the data indicated a substitutional H diffusion coefficient of 4.6 x 10-12cm2/s and an interstitial H diffusion coefficient of 1.5 x 10-11cm2/s.

Analysis of Hydrogen Diffusion from Proton-Exchanged Layers in LiNbO3. H.C.Casey, C.H.Chen, J.M.Zavada, S.W.Novak: Applied Physics Letters, 1993, 63[6], 718-20

Figure 27

Diffusivity of H in LiNbO3

(Open squares: 0mol%Li X-cut, open diamonds: 0mol%Li Y-cut, black squares: 0.5mol%Li Y-cut, speckled squares: 1mol%Li X-cut, black diamonds: 1mol%Li Y-cut, speckled diamonds: 0.5mol%Li X-cut, speckled triangles: 1mol%Li X-cut, open triangles: 0mol%Li Z-cut)