Formation of Eu(III) Nanoparticles on Borosilicate Sol−Gel Studied with Time-Resolved Luminescence Techniques

Abstract

The formation of Eu(III) nanoparticles in borosilicate sol−gels and the glass formation heat treatment effect on those particles were studied using luminescence techniques. The presence of the particles was observed using transmission electron microscopy (TEM) images followed by analysis with energy dispersive X-ray spectroscopy (EDS). These experiments showed the presence of particles with a large quantity of europium and chlorine and only small amounts of oxygen with sizes ranging from 30 to 100 nm. Heat treatment at 400, 600, and 800 °C lead to glass samples in which those particles were no longer observed. Steady-state and time-resolved luminescence techniques allowed a detailed study of Eu(III) photophysics in sol−gel and glass samples. In sol−gel matrices, the 5D0 → 7F0 transition is very weak, hinting at Eu(III) species experiencing a rather symmetric crystal field. The 5D0 → 7F2 transition intensity is not very strong, which according to a Judd−Ofelt analysis indicates low interaction with the ani...