The effects of heat treatments upon NO adsorption for a single crystal of LiNbO3

The effects of heat treatments in a vacuum chamber for a single crystal of LiNbO3 have been examined with XPS, CAICISS and NO adsorption as a model reaction. The single crystal of LiNbO3 was reduced by heating at 400°C for 1 h in a vacuum chamber. The loss of lithium and the creation of oxygen vacancies and lower valence niobium ions (Nb4+) were detected with XPS. The crystal structure of the topmost layer of the heated sample was detected as LiNbO3 in good order with CAICISS. Heating seems to order the topmost layer, and refill the vacancies by diffusion of oxygen and lithium through the surface. NO adsorbed as NO2 and NO3 on this ordered layer of LiNbO3.