Researchers from CEA DAM-DIF and Université Paris-Saclay made a big advance by successfully synthesizing single-crystalline -Fe or epsilon iron, a type of iron thought to occur in the Earth’s core. Epsilon iron is a hexagonal close-packed (HCP) phase of the metal that is only stable at extremely high pressures. The discovery could help us better comprehend the structure and makeup of our planet’s core.
The difficulties encountered in synthesizing Fe
Scientists had difficulties in synthesizing -Fe due to fractures throughout the procedure. When an atmospheric pressure phase of iron-ferrite or -iron is subjected to high pressure in order to compress it into -Fe, it typically fractures into tiny crystals that are insufficient for a thorough investigation. However, the research team overcomes these challenges by using a novel experimental approach.
This is how the ground-breaking synthesis was accomplished
According to the study, scientists compressed -iron at a pressure of 7GPa (gigapascals), causing the temperature to increase to roughly 527 degrees Celsius and resulting in the metamorphosis into -iron crystals. Despite the fact that -iron has a different structure than -iron, crystals were eventually transformed to -structure iron or hexaferrum phase by applying pressures ranging from 15 to 33GPa at 26.85 degrees Celsius. The characteristics of -Fe were then investigated using a synchrotron beamline.
Geophysical implications
The experiment was carried out to investigate the directionally-dependent elasticity of synthetic -iron, and the results indicate that its behavior is similar to that of iron in Earth’s core. Scientists believe that the majority of the iron in the Earth’s core is in this form, and a thorough understanding of the properties of synthetic -iron could aid in explaining why our planet’s center appears to have directional variations in texture.
