A study of the chemical reactions involved in Li-Ca-N system

The chemical reactions and phases involved in the potential flux system of Li-Ca-N for the growth of bulk GaN crystals have been investigated under varying conditions. It is found that no preferential nitrification of Li or Ca by N2 in Li-Ca melts at 500 °C. Only the ternary compound LiCaN is identified in the Li-Ca-N system under the present experimental conditions. Static N2 pressures are found to enhance the formation of LiCaN compared to an N2 stream. LiCaN forms from two possible pathways: one is a modified metathesis chemical reaction represented by Li3N+Ca→LiCaN+2Li, and the other is a combination chemical reaction represented by Li3N+Ca3N2→3LiCaN. The formation of LiCaN by the metathesis reaction is thermodynamically favored over the other pathway. In addition, the formation of LiCaN might benefit from a slightly larger initial amount of Li3N compared with Ca or Ca3N2. © 2006 Elsevier B.V. All rights reserved