Synthesis of Nd2Sn2O7 pyrochlore with different lattice disorder degrees and oxygen vacancy contents

In this study, a series of Nd₂Sn₂O₇ pyrochlores with different lattice disorder degrees and oxygen vacancy contents were prepared via simple methods, including the sol–gel (SG) technique, glycine–nitrate combustion (GNC), coprecipitation (CP), and the hydrothermal (HT) method. Raman spectroscopy proved the most effective in identifying the lattice disorder degree and lattice defects of the pyrochlore-type composite oxides, followed by XRD, with FTIR spectroscopy as the least sensitive technique. For pure phase Nd₂Sn₂O₇, the content of oxygen vacancies and adsorbed oxygen species follow the sequence CP > GNC > SG, which is well consistent with the lattice disorder degrees. This is because that the higher the lattice disorder of Nd₂Sn₂O₇ pyrochlore, the weaker the Sn-O bond, making it easier to break and form oxygen vacancies. Although the HT sample exhibits the lowest disorder degree, its synergistic effect with residual SnO₂ on the surface is beneficial for further enriching oxygen vacancies.