A novel method to synthesize GaN crystals was studied by the reaction of Ga with Li3N under NH3 atmosphere. We have already reported the synthesis technique of GaN by the reaction of Ga2O3 with Li3N. However, the size of GaN crystals obtained by this method was limited to be smaller than several micrometers because of the solid phase reaction. In order to increase the size of GaN crystals, the method using liquid Ga as gallium source was studied for solid-liquid phase reaction. We found that the GaN crystals with the size of more than 100 mu m were synthesized at 750 degrees C for 24h under NH3 atmosphere. We propose the possible reaction mechanism as follows. Lithium amide (LiNH2) is synthesized by the reaction of Li3N with NH3 gas and then the crystal growth of GaN occurs by the reaction of Ga with LiNH2. We found that LiNH2 is a useful nitrogen source for the GaN synthesis method. (C) 2009 Elsevier B.V. All rights reserved.