Host anion and cationdiffusion in lithium niobate at high temperatures

Lithium niobate, LiNbO, (LN), has excellent electro-optical, piezoelectric and acoustic properties. The production of LN based components as well as the increasing application of LN at high temperatures require understanding the atomic transport of the constituents. Regardless of the Li2O/Nb2O5 ratio Li is the most mobile species and is about 4 to 5 orders of magnitude more mobile than O in the temperature range 800 degrees C <= T <= 1100 degrees C, As to the Nb diffusion three controversial published data sets are compared to our recent measurements in LN, where we used Ta as a tracer to probe the self-diffusion of Nb in LN under a constant O-2 partial pressure of 200 mbar. From the resulting SIMS depth profiles of Ta a diffusivity was extracted which can be assumed to reflect the Nb self-diffusivity in LN. The obtained Ta(Nb) diffusivity is much lower than the values given in the literature. The significant discrepancies between our results and the literature data can be consistently rationalized if the experimental procedures of the earlier works are carefully analyzed especially with respect to the most probable point detect equilibria.