PRESSURE-INDUCED METASTABLE AMORPHIZATION OF BAS - EVIDENCE FOR A KINETICALLY FRUSTRATED PHASE-TRANSFORMATION

A transformation from the zinc blende (zb) to an amorphous crystal str ucture was observed at 125 GPa, just slightly above the calculated equ ilibrium transition pressure to the rock salt phase [Phys. Rev. B 36, 6058 (1987)]. This is the first evidence that pressure induced amorphi zation in AB compounds is a kinetically frustrated process. The amorph ous state persisted on further loading to 165 GPa, and throughout down -loading to 0 GPa. The Birch coefficients of the equation of state for the zb phase were determined to be B-0 = 148 +/- 6 GPa and B'(0) = 3. 9 +/- 0.3, in good agreement with theoretical calculations.