A group of physicists and geologists from CEA DAM-DIF and Université Paris-Saclay, along with colleagues from ESRF in Grenoble, and the European Synchrotron Radiation Facility, have achieved a breakthrough in synthesizing single-crystalline iron similar to what exists in the Earth’s core. Their research, published in Physical Review Letters, outlines their experimental method to create pure single-crystalline ε-iron and explores potential applications for this material.
Understanding Earth’s internal composition has largely relied on seismological data, revealing a solid core surrounded by liquid. However, certain anomalies, like the difference in seismic wave travel between pole-to-pole and equator-to-equator, have perplexed scientists for years. Many believe that the structure of iron in the core might hold the key to these mysteries.
Previous attempts to synthesize core-like iron for testing have failed due to fracturing during the process. The team overcame this challenge by compressing α-iron at 7GPa, raising its temperature to about 800 Kelvin, and transforming it into γ-iron crystals. With further pressure, the γ-iron transformed into ε-iron, believed to resemble the iron in Earth’s core.
Experiments conducted by the team demonstrated that their ε-iron displayed directionally-dependent elasticity, behaving similarly to iron in the Earth’s core, where vibrations travel faster along one axis of a sphere than the other. This innovative approach may pave the way for generating iron samples to test theories about the composition of Earth’s core.
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