Processing of Gd2O3:Eu phosphor particles through aerosol route

The processing of advanced materials with luminescent properties (phosphors) emphasizes the importance of ultrafine powder synthesis. Aerosol synthesis is applied for the preparation of Eu-activated gadolinium oxide matrices, commonly used as red phosphors in cathodoluminescence. The process involves aerosol formation ultrasonically (1.7 MHz) from the precursor salt solutions and control over the aerosol decomposition in a high-temperature (1173 K) tubular flow reactor. During decomposition, the aerosol droplets undergo evaporation/drying, precipitation and thermolysis in a single-step process. Consequently, spherical, solid, agglomerate-free, submicronic particles with the mean particle size below 1000 nm are obtained. In order to control the particles crystal structure and establish the conditions for the stabilization of the low-temperature gadolinia cubic phase, the process parameters like temperature distribution, gas flow rate and annealing temperatures were adopted. The particle morphology, phase and chemical structure are revealed in accordance to various analysis methods (XRD, DSC, SEM-EMAX, particle stereology and size distribution) and discussed in terms of precursor chemistry and process parameters. The mechanisms of ultrafine phosphor particles generation are focused and correlated with the luminescence properties. (C) 2003 Elsevier Science B.V. All rights reserved.