TY  - JOUR
A1  - Tiseanu, Carmen
A1  - Parvulescu, Vasile I.
A1  - Boutonnet, Magali
A1  - Cojocaru, Bogdan
A1  - Primus, Philipp A.
A1  - Teodorescu, Cristian M.
A1  - Solans, Conchita
A1  - Sanchez Dominguez, Margarita
T1  - Surface versus volume effects in luminescent ceria nanocrystals synthesized by an oil-in-water microemulsion method
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - Pure and europium (Eu3+) doped cerium dioxide (CeO2) nanocrystals have been synthesized by a novel oil-in-water microemulsion reaction method under soft conditions. In-situ X-ray diffraction and RAMAN spectroscopy, high-resolution transmission electron microscopy, UV/Vis diffuse-reflectance and Fourier transform infrared spectroscopy as well as time-resolved photoluminescence spectroscopy were used to characterize the nanaocrystals. The as-synthesized powders are nanocrystalline and have a narrow size distribution centered on 3 nm and high surface area of similar to 250 m(2) g(-1). Only a small fraction of the europium ions substitutes for the bulk, cubic Ce4+ sites in the europium-doped ceria nanocrystals. Upon calcination up to 1000 degrees C, a remarkable high surface area of similar to 120 m(2) g (-1) is preserved whereas an enrichment of the surface Ce4+ relative to Ce3+ ions and relative strong europium emission with a lifetime of similar to 1.8 ms and FWHM as narrow as 10 cm(-1) are measured. Under excitation into the UV and visible spectral range, the europium doped ceria nanocrystals display a variable emission spanning the orange-red wavelengths. The tunable emission is explained by the heterogeneous distribution of the europium dopants within the ceria nanocrystals coupled with the progressive diffusion of the europium ions from the surface to the inner ceria sites and the selective participation of the ceria host to the emission sensitization. Effects of the bulk-doping and impregnation with europium on the ceria host structure and optical properties are also discussed.
Y1  - 2011
U6  - https://doi.org/10.1039/c1cp21135h
SN  - 1463-9076
VL  - 13
IS  - 38
SP  - 17135
EP  - 17145
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -