Low-Temperature DC Conductivity of LiNbO3 Single Crystals

We report on conductivity measurements of LiNbO3 single crystals with congruent composition in ambient atmosphere between 449 and 727 K which include the lowest temperatures covered so far. The ionic DC conductivity observed along the c-axis at, e. g., 650 K is 6.7 x 10(-9) S/cm and shows an activation energy of 1.33 eV. The corresponding Li+ diffusion coefficients range between 2.5 x 10(-22) and 1.4 x 10(-16) m(2)/s. These results are perfectly consistent with our conductivity results in the high-temperature regime as well as SIMS measurements published recently (Rahn et al., Phys. Chem. Chem. Phys. 14 (2012) 2427). From the Li+ diffusion coefficients obtained here a Haven ratio of 0.7(2) can be deduced.