Thermal control of metathesis reactions producing GaN and InN

The addition of lithium amide (LiNH2) and ammonium chloride (NH4CI) to meta thesis (exchange) reactions between gallium triiodide (GaI3) and lithium ni tride (Li3N) produces crystalline gallium nitride (GaN) in seconds at ambie nt pressure. A specially designed rate cell incorporating multiple thermoco uples enables both the reaction velocity and temperatures to be measured. W ithout the additives, the GaI3/Li3N reaction propagates at > 100 cm/s with a reaction temperature above 1300 K, which exceeds tile 1150 K decompositio n temperature of GaN. By adding an optimal ratio of LiNH2 and NH4Cl, the re action velocity slows to about 3 cm/s with a reaction temperature near 1200 K. Rapid heat dissipation is found to be very important in these reactions in preventing the decomposition of GaN. By using a specially designed ther mal dissipation cell, the yield of GaN can be increased up to 78.8%. Applyi ng the concepts developed in the synthesis of GaN, crystalline InN has been synthesized for the first time using solid-state metathesis reactions.