Gd2O3 : Eu3+ phosphor particles processed through aerosol route

In this work, the influence of the Eu3+ luminescence center concentration on the structural, morphological and spectroscopic properties of powders obtained by an aerosol method was studied. In the method, gadolinium and europium nitrate solutions were ultrasonically aerosolised and fed into a high-temperature (up to 1200 degrees C) tubular flow reactor to control the aerosol decomposition. During decomposition, the aerosol droplets undergo evaporation/drying, precipitation and thermolysis in a single-step continuous process. Spherical, solid, agglomerate-free, submicron-sized particles with the crystallite sizes below 20 nm have been obtained. In order to control the particle crystal structure and to establish the conditions for the stabilization of the low-temperature gadolinia cubic phase, process parameters such as synthesis temperature, droplet/particle residence time and annealing temperatures were varied. The particle morphology, phase and chemical structure were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and EDS. Structural changes (crystallite size and microstrains) after powders thermal treatment were carried out using the Koalariet-XFit program as the profile-matching tool. The results obtained and the mechanisms for ultrafine phosphor particle generation are discussed in terms of precursor chemistry, process parameters and luminescence properties. (c) 2005 Elsevier Ltd. All rights reserved.