Effects of phonon confinement on the luminescence dynamics of Eu³⁺in Gd₂O₃nanotubes

Abstract

The effects of phonon confinement on the excited state dynamics of Eu3+ in Gd2O3 nanotubes are investigated. Anomalous thermalization appears due to elimination of low-energy phonon modes in this highly efficient nanophosphor of many potential applications. It is observed that in the low-temperature excitation spectrum hot bands with fine structures originate from the lowest sublevel of 7F1 at 217 cm−1 above the ground state. The intensity of the hot bands hardly changes below 50 K, but it increases and exhibits normal Boltzmann thermalization above 50 K. The fluorescence lifetime of 5D0 (2.19 ms at 10 K) is found to be unusually longer than that of the bulk counterparts, indicating a small filling factor of 0.55 for the nanotubes. These luminescent properties are attributed to the morphology and to the lack of low-energy phonon modes in the nanotubes.