Low symmetry phases of (Al, Ga)Sb under low pressure

Abstract

The interesting problem of the first phase transition which is induced by pressure in AlSb and GaSb antimonide binaries is revisited. Then, the case of the AlGaSb ternary has been investigated too. The choice of ternary AlGaSb is due to the particular attention which is given actually to it and to the quasi-absence of investigations of the phase transitions in it. We found that low pressures applied to GaSb and AlSb induce transitions from zinc-blende to Imm2 and from zinc-blende to Cmcm, respectively. Our result for AlSb is in agreement with literature, and in the case of GaSb which poses the problem, we find that the Imm2 phase presents a lower total energy than the b-β-Sn phase. For ternaries, the transition is found to be to a phase which is obtained from the Cmcm phases of binaries. Calculations were performed using the plane wave version of the FPLMTO (PLW-FPLMTO) first principle method based on the local density approximation (LDA) and the generalized gradient approximation (GGA96).