Luminescent lanthanide oxides nanoparticles with a surface agent acting as a sensitiser

Abstract

This work describes a series of lanthanide oxide nanoparticles, Nd2O3, Sm2O3, Eu2O3, TbO1.81, and Dy2O3 (Ln2O3-NPs) synthesised using a modified Polyol method. These oxides exhibit small particle sizes ranging from 5 nm to 20 nm, according to HRTEM micrographs, and crystallise into a cubic phase with an I213 space group. We employed deprotonated 2,3-dihydroxyquinoxaline (L2−) as a capping agent and sensitiser for nanoparticle luminescence. Spectroscopic results indicate that L2− is an excellent antenna. This work presents photoluminescence and absorption spectra of the Ln2O3 NPs, naked and with the capping agent. We also include the emission spectra at low temperatures (200 K and 100 K) and variable pressure for which a significant Stark level splitting was observed in the case of Sm2O3-L2- NPs. This splitting agrees with a D3 site symmetry for the samarium ion, being low symmetry. All compounds exhibit excellent luminescence properties; further studies may determine their possible use as optical sensors.