Here, we report on the effect of mixing state of raw materials on the solid-state synthesis of Ce3+-doped Y3Al5O12 (Y2.97Al5O12:Ce-0.03(3+), YAG:Ce3+) phosphors for white light emitting diodes. The mixed powders were prepared by the mechanical method using an attrition-type mill. Homogeneously mixed powder in nanoscale of raw powder materials was favorably obtained by the mechanical method. It achieved the synthesis of YAG:Ce3+ by heating at 1400 degrees C which was 400 degrees C lower than the synthesis temperature of the mixed powder by ball milling. Besides, larger crystallite size was obtained by heating the powder at higher temperature. The YAG:Ce3+ phosphor synthesized at 1800 degrees C exhibited the largest crystallite size, thus led to maximum external quantum yield of 55%, and the luminous efficiency of 97% at 150 degrees C. It revealed the highest efficiency in the previously reported values. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.