Study of Oxygen Vacancies in Ce0.9Pr0.1O2-δ Solid Solution by in Situ X-ray Diffraction and in Situ Raman Spectroscopy

Abstract

A Ce0.9Pr0.1O2-δ solid solution was prepared by a sol−gel method. Changes in microstructure of the solid solution under different atmospheres (O2, He, and H2) and temperatures were characterized by an in situ X-ray diffraction (XRD) technique. Raman peaks at 460 cm-1 ascribed to the F2g vibration mode of CeO2 in the fluorite structure and at 570 cm-1 ascribed to oxygen vacancies in the solid solution were studied by in situ Raman spectroscopy using 785- and 514-nm excitation laser lines, providing bulk and surface information, respectively. With a 785-nm laser line, the A570/A460 ratio reflecting the oxygen vacancies concentration increased under O2 and He while it first increased and then decreased under H2 with increasing temperature. With a 514-nm excitation laser line, the A570/A460 ratio decreased with increasing temperature under all atmospheres. The growth of the A570/A460 ratio under the 785-nm laser line was due to the positive effects of high temperature and high concentration of oxygen vacancie...