Well-dispersed nano-sized gallium nitride (GaN) and magnesium-doped GaN (GaN:Mg) particles were successfully prepared from nano-sized gallium oxide (Ga2O3) particles under a flow of ammonia gas. The gallium oxide nanoparticles were prepared from mixtures of gallium nitrate aqueous solution and ammonia solution that were heated to between 600 and 800 degrees C. Addition of a proportional amount of ammonia into the solution is a key point for production of well-dispersed nano-sized gallium oxide particles. Gallium oxide nanoparticles less than 20 nm in size were obtained when using an NH3 to Ga(NO3)(3) ratio of 1:1 (mol/mol) with a heating temperature of 800 degrees C. Nitridation of gallium oxide nanoparticles under a flow of ammonia at a heating temperature of 800 degrees C resulted in nano-sized GaN particles less than 40 run in size. We investigated the effects of preparation conditions such as solution composition and operating temperature on the characteristics of gallium nitride particles. This method allows simple doping of GaN with alkali earth metals. It was shown that the doping with magnesium resulted in intense blue luminescence from particles when UV excitation at 254 nm was used. (c) 2005 Elsevier B.V. All rights reserved.