Luminescent properties of pure cubic phase Y2O3/Eu3+ nanotubes/nanowires prepared by a hydrothermal method

One-dimensional pure cubic Y2O3/Eu3+ nanocrystals (NCs) were synthesized by a hydrothermal method at various temperatures. The NCs prepared at 130 degrees C yielded nanotubes (NTs) with wall thickness of 5-10 nm and outer diameter of 20-40 nm. The NCs prepared at 170 and 180 degrees C yielded nanowires (NWs) with diameters of similar to 100 and similar to 300 nm, respectively. Their luminescent properties, including electronic transition processes, local environments surrounding Eu3+ ions, electron-phonon coupling, and UV light irradiation induced spectral changes have been systematically studied and compared. The results indicate that the Y2O3/Eu3+ NTs and NWs have strong red D-5(0)-F-7(2) transitions. The fluorescence lifetime of D-5(1)-F-7(1) hardly changes in different samples, while that of D-5(0)-F-7(2) decreases a small amount in Y2O3/Eu3+ NTs. The D-5(0)-F-7(2) lines originate from the emissions of Eu3+ ions occupying one C-2 site, like that in the bulk powders. The phonon sideline with a frequency shift of 40-50 cm(-1) appears at the low-energy side of the F-7(0)-D-5(0) zero phonon line. The relative intensity of the sideline to zero phonon line increases by varying from NTs to NWs, and the spectral position of the phonon sideline shifts red. The UV light irradiation induced spectral change in the charge-transfer band was studied. The results indicate that the spectral change is dependent on sample size and is wavelength selective. A detailed model was proposed to explain the light-induced spectral change.