The Orthorhombic Structure of Iron: An in Situ Study at High-Temperature and High-Pressure

Abstract

An in situ angle-dispersive x-ray diffraction study was undertaken of iron in a laser-heated, diamond-anvil cell up to 2375 kelvin and between 30 and 100 gigapascals in Al 2 O 3 - and SiO 2 -pressure media. The resolution and reliability of diffraction peak intensities allow quantitative assessment of a structural model. The results confirm that iron undergoes a phase transformation at high pressures and temperatures. The space group is Pbcm for an orthorhombic lattice, and the atomic topology is close to that of ɛ hexagonal close-packed iron.