Mössbauer Spectrum of Iron-57 in Iron Metal at Very High Pressures

The effect of pressure on the Mössbauer spectrum of Fe(57) in iron metal has been studied as the pressure was increased presumably to more than 140 kbar. At pressures up to 120 kbar, a six-line spectrum characteristic of alpha-iron was observed. At 140 kbar, a seventh line appeared in the spectrum at -0.12 +/- 0.06 mm/sec relative to stainless steel. This line was attributed to the appearance of the high-pressure phase of iron.