18O/16O isotope exchange in combination with SIMS depth-profiling was used to

investigate oxygen transport in Li2O-deficient single crystalline LiNbO3 at 983 to

1188K under 200mbar of oxygen. Within the limits of experimental error and for

the investigated range of temperatures, no significant differences between transport

parallel and transport perpendicular to the c-axis were found. The temperature

dependences for oxygen tracer diffusion were:

D (m2/s) = 6.4 x 10−3exp[−333(kJ/mol)/RT]

and, for oxygen surface exchange,

k (m/s) = 7.8 x 102exp[−288(kJ/mol)/RT]

The activation enthalpy obtained for tracer diffusion can be interpreted as the

enthalpy of migration of extrinsic oxygen vacancies induced by impurities with

lower valency on niobium sites.

Oxygen-18 Surface Exchange and Diffusion in Li2O-Deficient Single Crystalline

Lithium Niobate. P.Fielitz, G.Borchardt, R.A.De Souza, M.Martin, M.Masoud,

P.Heitjans: Solid State Sciences, 2008, 10[6], 746-53