Defect and intrinsic luminescence of CeO₂nanocrystals

Abstract

In the paper, the luminescence processes in CeO2 nanocrystals have been investigated and several types of luminescent centers were revealed. For CeO2 nanocrystals treated in oxidation atmosphere two possible pathways of relaxation of the charge transfer excitation led to intrinsic charge transfer (CT) luminescence and luminescence of F0-centers. Treatment in reducing atmosphere leads to formation of additional luminescent centers formed by Ce3+ ions which charge is compensated by oxygen vacancies in first coordination sphere of Ce3+ ion. Shallow defects related to F+-centers present near edge of 4f0 band modify sufficiently the processes of excitation relaxation forming excitation traps that provide a series of trapping–retrapping acts during excitation lifetime.