Defects induced in cerium dioxide single crystals by electron irradiation

• Published in: Journal of applied physics 2018-01, Vol.123 (2)
• Main Authors: Costantini, Jean-Marc, Miro, Sandrine, Touati, Nadia, Binet, Laurent, Wallez, Gilles, Lelong, Gérald, Guillaumet, Maxime, Weber, William J.
• Format: Article
• Language: English
• Subjects: Absorption spectra; Anisotropy; Applied physics; Cerium dioxide; Cerium oxides; Crystal defects; Dioxides; Electron irradiation; Electron paramagnetic resonance; electron paramagnetic resonance spectroscopy; Fluence; Fluorite; Helium; MATERIALS SCIENCE; Radiation damage; Raman spectroscopy; Single crystals; Spectrum analysis; UV-visible optical absorption spectroscopy
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.5007823

Micro-Raman spectroscopy, X-band electron paramagnetic resonance (EPR) spectroscopy, and UV-visible optical absorption spectroscopy were used to study the damage production in cerium dioxide (CeO2) single crystals by electron irradiation for three energies (1.0, 1.4, and 2.5 MeV). The Raman-active T2g peak was left unchanged after 2.5-MeV electron irradiation at a high fluence. This shows that no structural modifications occurred for the cubic fluorite structure. UV-visible optical absorption spectra exhibited a characteristic sub band-gap tail for 1.4-MeV and 2.5-MeV energies, but not for 1.0 MeV. Narrow EPR lines were recorded near liquid-helium temperature after 2.5-MeV electron irradiation; whereas no such signal was found for the virgin un-irradiated crystal or after 1.0-MeV irradiation for the same fluence. The angular variation of these lines in the {111} plane revealed a weak g-factor anisotropy assigned to Ce3+ ions (with the 4f1 configuration) in a high-symmetry local environment. It is concluded that Ce3+ ions may be produced by a reduction resulting from the displacement damage process. However, no evidence of F+ or F0 center or hole center formation due to irradiation was found from the present EPR and optical absorption spectra.