Phase-Transition Pressures of Fe_3O_4 and GaAs Determined from Shock-Compression Experiments(Physics)
Shock-wave technique is used in order to observe the phase transition of two iron oxides, magnetite (Fe_3O_4) and hematite (αFe_2O_3), and two semiconductors, GaAs and GaP. Shock data up to about 500 kbar are obtained by streak-camera photography. Phase-transition pressure in magnetite is determined from two inclined mirror runs to be 216±15 kbar, which is appreciably lower than the corresponding value at static pressures, 250±15 kbar. Two inclined mirror runs for GaAs reveal a three-wave structure, yielding a Hugoniot elastic limit and apparent phase-transition pressure of 84±8 kbar and 203±11 kbar. If a correction due to the shear strength effect on the phase transition is taken into consideration, this value is reduced to be 162±11 kbar, which is again remarkably lower than the static value of 193±5 kbar or 180±1 kbar. The observed discrepancy between transition pressures determined from static and dynamic means suggests a partial loss of shear strength in shocked GaAs. Preliminary experiments on αFe_2O_3 and GaP indicate phase transitions above about 500 kbar and at about 260 kbar respectively.
- Science reports of the Research Institutes, Tohoku University. Ser. A, Physics, chemistry and metallurgy
Science reports of the Research Institutes, Tohoku University. Ser. A, Physics, chemistry and metallurgy 27 72-72, 1979