NO adsorption on a single crystal and a polycrystalline powder of LiNbO3

NO has been adsorbed as NO2− and NO3− on an LiNbO3 single crystal at room temperature. NO− was observed in the XPS spectrum for the N 1s level of the LiNbO3 single crystal after exposure at 200 and 400 °C, respectively. An LiNbO3 polycrystalline powder had only a peak from NO3− after exposure between room temperature and 400 °C. The oxygen vacancies of lattice oxygen were produced with both LiNbO3 samples after exposure at room temperature. These oxygen vacancies in the LiNbO3 single crystal were partially refilled with NO− after exposure at 200 and 400 °C. On the other hand, the vacancies associated with the polycrystalline powder were partially refilled by the out-diffusion of oxygen ions from the bulk to the surface after exposure at 200 and 400 °C. The ions of lithium and oxygen in the bulk LiNbO3 polycrystalline powder diffuse more easily to its surface than those present in the LiNbO3 single crystal.