Congruently grown single crystals exhibited high O and Li ionic conductivities at above 500C. The high O ionic conductivity was explained in terms of a certain number of O vacancies which were already present in congruent as-grown single crystals. An electrocoloration phenomenon in single crystals was attributed to a process in which Li ions and electrons were injected by a double charge mechanism. The optical and electrical properties of electrocolored crystals were investigated: The motion of stoichiometric domains (regions with different stoichiometry) through a crystal from one electrode to another was studied and was described in terms of electrodiffusion of the ions and electrons.

Peculiarity of O2- and Li+ Electrodiffusion into Lithium Niobate Single Crystals. S.Bredikhin, S.Scharner, M.Klinger, V.Kveder, B.Redkin, W.Weppner: Solid State Ionics, 2000, 135[1-4], 737-42