Synthesis and up-conversion luminescence of erbium-doped yttrium silicate single crystal nanoparticles tailored by the mesoporous silica template

Abstract

Erbium-activated yttrium silicate nanoparticles were tailored using a mesoporous silica template. Transmission electron microscopy (TEM) revealed that the synthesized particles are single crystals of yttrium pyrosilicate (α−Y2Si2O7:Er), possessing a spherical shape (with an average size of about 210 nm) and a narrow size distribution. Up-conversion luminescence of the synthesized particles was investigated in the green spectral region under excitation by a laser diode operating at a wavelength of 808 nm. In the range of 510-580 nm, intense narrow lines with a Lorentzian shape were observed, attributed to radiative transitions from two thermally coupled energy levels of the Er3+ ion [2H11/2→4I15/2 (520–540 nm) and 4S3/2→4I15/2 (545–570 nm)]. It was experimentally demonstrated that within the temperature range of 250–520 K, the equilibrium populations of the 2H11/2 and 4S3/2 levels follow the Boltzmann distribution. This result provides a basis for the potential use of the synthesized particles as temperature sensors in various applications, including biomedical ones.