Bharat SainiLast Updated on May 5, 2017 by Bharat Saini
A recent study by scientists at KTH Royal Institute of Technology has found that iron at the core of the Earth, is in Body-Centered Cubic (BCC) phase crystal architecture with eight corner points and a center point, where pressure is 3.5 million times higher than surface pressure and temperatures are some 6,000 degrees higher. Study reveals that though the inner core of the Earth is hotter than the surface of the Sun, the crystallized iron core of the Earth remains solid and does not melt and found that seismic waves travelling in between the planet’s poles are at higher speeds than those between the equator, that is one sign of the textured nature of the solid iron inner core of the Earth.Scientists have found that the edge of the inner core, pieces of crystals’ structure continuously melt and diffuse only to be reinserted due to high pressure like shuffling deck of cards.This energy distribution cycle keeps the crystal stable and the core solid.
According the seismological studies, Earth’s inner core is its innermost part and has been believed to be primarily a solid ball with a radius of about 1,220 kilometers, which is about 70% of the Moon’s radius. It is composed of an iron–nickel alloy and some light elements, with temperature as high as 5400 °C.
A crystal ball i.e. a mass formation of almost pure crystallized iron is spinning within Earth’s molten core. Knowing atomic structure of these crystals leads to understanding the above strange, unobservable feature of our planet.
As with all metals, the atomic-scale crystal structures of iron change depending on the temperature and pressure, the metal is exposed to. Atoms are packed into variations of cubic, as well as hexagonal formations. At room temperatures and normal atmospheric pressure, iron is in what is known as a body-centered cubic (BCC) phase;but at extremely high pressure the crystalline structures transform into 12-point hexagonal forms, or a close packed (HCP) phase.
At low temperature, BCC is unstable and crystalline planes slide out of the ideal BCC structure. But at high temperatures, the stabilization of these structures begins much like a card game,with the shuffling of a deck. In the extreme heat of the core, atoms no longer belonged to planes because of the high amplitude of atomic motion.The sliding of these planes is a bit like shuffling a deck of cards. Even though the cards are put in different positions, the deck is still a deck. Likewise, the BCC iron retains its cubic structure.Such a shuffling leads to an enormous increase in the distribution of molecules and energy, which leads to increasing entropy, or the distribution of energy states and makes the BCC stable. In this study the researchers looked into larger computational samples of iron than studied previously, characteristics of the BCC iron that were thought to render it unstable wound up doing just the opposite.
