Earth’s inner core may be rich in oxygen

(ORDO NEWS) — Previously, it was believed that oxygen, most likely, is not present in the composition of the iron inner core of the Earth.

However, in a new experiment, scientists were able to simulate the extreme conditions of this environment and obtain an iron-rich Fe-O alloy that can exist at temperatures of more than 2700 degrees Celsius and pressures of 300 gigapascals.

Oxygen, essential for the life of most creatures, is one of the most abundant chemical elements on Earth.

However, until now it has remained a mystery whether it is present in the inner core of our planet, which consists almost entirely of iron. If so, in what form does oxygen exist under conditions of extremely high temperature and pressure?

Now, scientists from the Center for Advanced Research in High Pressure Science and Technology (China) and Columbia University (Columbia) have shown that iron-rich Fe-O alloys remain stable at pressures of almost 300 gigapascals (approximately three million atmospheres) and temperatures of more than 2700 degrees. Celsius. The results of the study prove that oxygen can exist in our planet’s solid inner core.

The Earth’s inner core remains one of the most mysterious places on the planet. The pressure in it can reach 360 gigapascals, and the temperature is 5400 degrees Celsius, almost like on the surface of the Sun.

Since the core is far beyond human reach, scientists can only infer its density and chemical composition from indirect seismic signals.

It is believed that light elements may be in the core, but the question of their type and concentration is still controversial.

Cosmochemical and geochemical data indicate that the core must contain sulfur, silicon, carbon and hydrogen.

Experiments and calculations have also confirmed that these elements mix with pure iron to form various alloys.

However, the presence of oxygen in the core is usually ruled out. This is mainly due to the fact that iron-rich Fe-O alloys have never been found on the surface or in the mantle environment.

Although scientists have tried to synthesize iron oxide compounds with an iron-rich composition, no such substances have yet been found.

To approach the temperature and pressure of the Earth’s core in the experiment, the authors of the new work placed iron and iron oxide on the tips of two diamond anvils and heated them with a high-energy laser beam.

It turned out that the chemical reaction between these substances occurs at pressures above 220-260 gigapascals at a temperature of 2700 degrees Celsius.

The theoretical search for the crystal structure of the resulting iron-rich Fe-O alloy showed that it can stably exist in the conditions of the earth’s core.

In this case, the new Fe-O alloys form a hexagonal close-packed structure in which oxygen layers are located between the iron layers and stabilize the structure.

This mechanism creates many close-packed layers. Further calculations demonstrated that iron-rich Fe-O alloys are metallic, in contrast to conventional iron oxides at low pressures.


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