Control and enhancement of the oxygen storage capacity of ceria films by variation of the deposition gas atmosphere during pulsed DC magnetron sputtering

摘要

In this study, nanostructured ceria (CeO2) films are deposited on Si(100) and ITO coated glass substratesby pulsed DC magnetron sputtering using a CeO2 target. The influence on the films of using various gasambients, such as a high purity Ar and a gas mixture of high purity Ar and O2, in the sputtering chamberduring deposition are studied. The film compositions are studied using XPS and SIMS. These spectrashow a phase transition from cubic CeO2 to hexagonal Ce2O3 due to the sputtering process. This is relatedto the transformation of Ce4þ to Ce3þ and indicates a chemically reduced state of CeO2 due to the formation of oxygen vacancies. TGA and electrochemical cyclic voltammetry (CV) studies show that filmsdeposited in an Ar atmosphere have a higher oxygen storage capacity (OSC) compared to films depositedin the presence of O2. CV results specifically show a linear variation with scan rate of the anodic peakcurrents for both films and the double layer capacitance values for films deposited in Ar/O2 mixed and Aratmosphere are (1.6 ± 0.2) 10 4 F and (4.3 ± 0.5) 10 4 F, respectively. Also, TGA data shows that Arsputtered samples have a tendency to greater oxygen losses upon reduction compared to the filmssputtered in an Ar/O2 mixed atmosphere.