Positron annihilation spectroscopic studies on Nd-doped ceria

✍ Scribed by A. Sachdeva; S.V. Chavan; A. Goswami; A.K. Tyagi; P.K. Pujari

• Book ID: 104029246
• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 225 KB
• Volume: 178
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1016/j.jssc.2005.04.016

✦ Synopsis

We report a new result on the characterization of Nd-doped ceria, Ce 1Àx Nd x O 2Àx/2 (x ¼ 0:07520:675) using positron lifetime spectroscopy (LTS) and coincidence Doppler broadening (CDB) measurements. A systematic increase in lifetime that is attributed to formation of Nd-oxygen vacancy associates is seen from x ¼ 0:075-0.4 followed by a sharper increase up to x ¼ 0:5. The change in profile of lifetime around x ¼ 0:4 suggests drastic increase in the concentration of these associates. Discontinuity in lifetime around x ¼ 0:5 is ascribed to ordering of oxygen vacancies. Coincidence Doppler broadening measurements indicate reduction in the overlap of positron wavefunction with oxygen core electrons due to trapping of positrons. Low-temperature (50-300 K) lifetime measurements indicate the presence of Rydberg-like positron states associated with Nd 3+ sites.