Abstract
We have investigated the structure of liquid GaSb up to 20 GPa by a high-pressure and high-temperature x-ray-diffraction technique. With increasing pressure, the hump at high- side of the first peak in the structure factor, reflecting an anisotropic local structure becomes smaller and the ratio of the wave number of the second peak to that of the first one, decreases. Simultaneously, the coordination number CN increases in correspondence to the elongation of the nearest-neighbor distance compared to that expected from a uniform contraction model. These findings suggest that the liquid GaSb contracts nonuniformly and the local structure changes with pressure. Analysis of the pair distribution function by a distorted-crystalline model shows that the liquid consists of two parts similar to the -Sn and body-centered cubic (bcc) structures which are realized in the high-pressure crystalline phases, rather than the zinc-blende structure in an ambient phase. The fraction of the bcc-like local structure increases continuously from to as the pressure is raised from 1.7 GPa to 20 GPa. The pressure dependence can be explained quantitatively by Rapoport’s two-species model [J. Chem. Phys. 46, 2891 (1967)]. The observed elongation of the nearest-neighbor distance and the increase of CN would be attributed to the continuous change of the local structure from the -Sn-like one into the bcc-like one under pressure.
- Received 25 June 2003
DOI:https://doi.org/10.1103/PhysRevB.68.224106
©2003 American Physical Society