Amorphization from the quenched high-pressure phase in tetrahedrally-bonded materials

X-ray diffraction of GaAs and InAs has been measured at pressures up to 25 GPa and at temperatures down to 90 K by an energy dispersive method using synchrotron radiation. When pressure was released at low temperature, the metallic high-pressure phase was quenched. In GaAs, amorphization from the quenched high-pressure phase occurs from 140 to 260 K when temperature is increased at 5 GPa, and from 170 to 270 K at 8 GPa. Similar amorphization occurs on decompression at 160 and 220 K. In InAs, phase transition from the quenched high-pressure phase to a micro-crystalline zinc-blende phase occurs when temperature is increased at 2.5, 2.0 and 1.5 GPa. These results are discussed in connection with the pressure dependence of potential barriers for the phase transitions by using a configuration-coordinate model. The effects of strength and ionicity of bonds on amorphization are also discussed in connection with the phase transitions in other tetrahedrally-bonded materials.