Enhancement of photoluminescence properties in Er3+-doped Gd3ScxGa5−xO12 garnet nanocrystals by Sc3+ co-doping

Abstract

In this work, a series of novel garnet nanocrystals Gd3ScxGa5−xO12 (x = 0–2) doped with fixed Er3+ content were synthesized by a sol-gel combustion method. The structure, morphology, chemical composition, optical reflectance, and photoluminescence properties of the nanocrystals were investigated in detail. Following 980 nm laser excitation, steady-state and time-dependent Stokes Er3+: 4I13/2 → 4I15/2 emission spectra are investigated together with steady-state upconversion photoluminescence (UCPL) emission spectra. Although the activator content at the dodecahedral site is fixed, incorporation of Sc3+ into the octahedral site of the garnet host enhances the photoluminescence properties. The Stokes photoluminescence intensity keeps increasing with increasing Sc3+ content in the studied region. However, the intensity of UCPL is significantly increased in the Er3+-doped Gd3Sc2Ga3O12 sample. It is found that the substitution of Ga3+ by Sc3+ at the octahedral site of the studied garnet nanocrystals leads to a reduction of the maximum phonon energy and may affect the crystal field surrounding Er3+.