Yttrium aluminum garnet (YAG) nano-sized. powder was prepared by co-precipitation method assisted by ultrasonic display using different precipitating agent. The precursor powder can crystallize into YAG phase after being calcined at 900 degreesC for 2 h, because of the uniformly distribution of Al and Y elements. DTA-TG and IR measurements on the precursor powder obtained were performed to improve the synthesis process. X-ray diffraction was conducted on the powder calcined at different temperatures to investigate the effect of reaction conditions on particle size and phase composition. The powder about 15 nm in diameter with pure YAG was obtained at lower temperature (900 degreesC) by controlling the pH value, precipitating agent and doping agent. (C) 2003 Elsevier B.V. All rights reserved.