Down-conversion of UV radiation in erbium-doped gadolinium oxide nanoparticles

Properties optimization and improvement of functional characteristics of lanthanide-based nanomaterials for energy conversion systems require in-depth understanding of radiative and non-radiative relaxation mechanisms. In present work, we consider this task by researching the temperature behavior of luminescence in Gd2O3:Er nanoparticles under direct and indirect conversion of UV radiation into visible light. The temperature dependences of emission have non-trivial forms and contain two separate regions. Accounting the structural disorder of the host lattice we reveal two types of Gd3+ donor centers with different energy parameters. As a consequence, the Gd3+ -> Er3+ energy transfer leads to a bimodal character of activation energy of luminescence quenching for Er3+ acceptors. It causes a decrease in quantum efficiency of emission which also depends on activator's concentration. The thermal losses take lower values for nanoparticles with a lower concentration of Er3+ ions (1%). It indicates that in such nanoparticles the Gd3+ -> Er3+ energy transfer can be used as an additional channel for conversion of UV radiation with improved efficiency. (C) 2018 Elsevier Ltd. All rights reserved.