Theoretical study of the decomposition mechanism of a series of group III triazides X(N 3 ) 3 (X = B, Al, Ga)

Density functional theory method is used to examine a series of group III triazides X(N 3 ) 3 (X = B, Al, Ga). These compounds, except for the C 3 h planar B(N 3 ) 3 and Al(N 3 ) 3 , are first reported here. C 3 h planar structures are the most energetically favored for all singlet X(N 3 ) 3 systems. Potential‐energy surfaces for unimolecular decompositions of the C 3 h and C S planar X(N 3 ) 3 species have been investigated. Results show that decomposition of B(N 3 ) 3 obeys sequential fashion and follows a four‐step mechanism: (1) B(N 3 ) 3 → NB(N 3 ) 2  + N 2 ; (2) NB(N 3 ) 2 → cyc‐N 2 BN 3  + N 2 ; (3) cyc‐N 2 BN 3 → trigonal‐BN 3  + N 2 ; (4) trigonal‐BN 3 → linear‐NBNN. Decomposition of Al(N 3 ) 3 follows a two‐step mechanism: (1) Al(N 3 ) 3 → NAl(N 3 ) 2  + N 2 ; (2) NAl(N 3 ) 2 → linear‐AlN 3  + 2N 2 . The dissociation of Ga(N 3 ) 3 follows only one‐step mechanism: Ga(N 3 ) 3 → angular‐GaN 3  + 3N 2 . These findings may be helpful in understanding the decomposition mechanisms of group III triazides as well as the possible mechanism for XN film generation. © 2014 Wiley Periodicals, Inc.