Intrinsic Defect‐Assisted UV–Visible Energy Conversion in Gd2O3:Er Nanoparticles.

The correlations between defectiveness and optical properties of Er‐doped Gd2O3 nanoparticles coupled into cubic and monoclinic crystal structures were studied employing XPS and PL spectroscopies. The main focus of this research is paid to the cubic Gd2O3 phase, which is more suitable for light‐emitting purposes. It is shown that oxygen‐related point defects are the precursors for the formation of cationic irregulars – "defective" Gd3+ ions with local energy levels in the energy band gap of Gd2O3. Energy transfer from Gd3+ intrinsic defects to Er3+ dopants provides an additional channel for UV–visible radiation conversion. These Er3+ ions have bimodal distribution due to the non‐equivalent lattice sites of "defective" Gd3+ ions. An increase of Er3+ concentration leads to the giant phonon softening effect, which opens up a new prospective way to enhance energy conversion efficiency. [ABSTRACT FROM AUTHOR]