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

Abstract

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.

Structural and optical characterisation of silanised Dy-doped-Gd2O3 NPs

“…Some authors have reported a similar emission, especially for the bare nanostructured gadolinium oxide. 55 For instance, R. Mohan et al reported a broad emission around 400 nm for cubic Gd 2 O 3 NPs, synthetised using the precipitation method. 56 Hence, its energy can be modulated depending on the employed methodology, particle size, and morphology.…”

“…76 The broadband from 400 to 550 nm may originate from defects or radiative recombination of photogenerated holes with electrons occupying oxygen vacancies. 55,56,62 The emissions caused by defects have been widely discussed for other nanostructured systems, e.g. in ZnO.…”

Defect‐Induced Effects in Nanomaterials

“…Nanoparticles and quantum dots. Y. Kuznetsova et al reported the intrinsic defect‐assisted UV‐visible energy conversion in Gd 2 O 3 :Er nanoparticles. M. Skapas et al performed a high‐resolution transmission electron microscopy study of Bi quantum dots in annealed GaAsBi/AlAs multiple quantum wells.…”