Photoluminescence, cathodoluminescence and micro-Raman investigations of monoclinic nanometre-sized Y2O3 and Y2O3:Eu3+
Herein we describe a large scale synthesis of nanosized, monoclinic Y2O3 and Y2O3:Eu3+ with 2 mol% Eu3+ in a plasma-discharge chamber. This high yield synthesis provided nanosized particles with dimensions between 5 nm to 50 nm, which were stable during shelf life at ambient conditions for more than 6 years. We assume that the Gibbs–Thomson effect is responsible for this unexpected high stability. Annealing at 950 °C completely transformed the monoclinic particles into the cubic phase, which was indicated by the photo- and cathodoluminescence emission spectra in addition to the much stronger light output. The undoped Y2O3 material was contaminated with Dy3+, which showed characteristic and rather strong luminescence upon activation with a He–Ne laser at 632.8 nm, both at the Stokes and anti-Stokes side. Photoluminescence, cathodoluminescence and Raman spectra of the undoped and doped monoclinic nanocrystals were recorded and partially interpreted.