The morphology of BaMgAl10O17:Eu2+ phosphor particles was controlled by changing the precursor solution used in the spray pyrolysis. The colloidal and aqueous solutions were obtained using aluminum isopropoxide and aluminum nitrate as the source of aluminum. The characteristics of particles prepared from colloidal solution were compared with those of particles prepared from aqueous solution. The particles prepared from colloidal solution maintained their spherical structure and nonaggregation characteristics of as-prepared particles even after post-treatment at 1400 degrees C while aggregation was observed to take place in the particles pre pared from aqueous solution. The high thermal stability of particles prepared from colloidal solution was attributed to the stable intermediate, MgAl2O4. For the highest crystallinity and brightness of particles, the optimum post-treatment temperature was found to be 1200 degrees C. The particles prepared from colloidal solution had higher crystallinity than those prepared from aqueous solution. (C) 2000 The Electrochemical Society. S0013-4651(99)07-066-4. All rights reserved.