Synthesis of Y3Al5O12:Ce3+ colloidal nanocrystals by pulsed laser ablation and their luminescent properties

Cerium-doped Y3Al5O12 (YAG:Ce3+) colloidal nanocrystals were synthesized by pulsed laser ablation (PLA) in de-ionized water and lauryl dimethylaminoacetic acid betain (LDA) aqueous solution for luminescent bio-labeling application. The influence of LDA molecules on the crystallinity, crystal morphology, crystallite size and luminescent properties of the prepared YAG:Ce3+ colloidal nanocrystals was investigated in detail. When the LDA solution was used, smaller average crystallite size, narrower size distribution and enhanced luminescence were observed. These characteristics were explained by the effective role of occupying the oxygen defects on the surface of YAG:Ce3+ colloidal nanocrystal because the amphoteric LDA molecules were attached by positively charged YAG:Ce3+ colloidal nanocrystals. The blue-shifted phenomena found in luminescent spectra of the YAG:Ce3+ colloidal nanocrystals could not be explained by previous crystal field theory. We discuss the 5d energy level of Ce3+ with decreased crystal size with a phenomenological model that explains the relationship between bond distance with 5d energy level of Ce3+ based on the concept of crystal field theory modified by covalency contribution. (C) 2013 Elsevier B.V. All rights reserved.