One longstanding mystery about the inner core is that it is rather soft, with rather low shear wave velocity. The scientists calculated the seismic velocities in these superionic iron alloys and found a significant decrease in shear wave speed. “Our outcomes fit well with seismological observations. It is the liquid-like components that make the inner core soften,” stated co-first author SUN Shichuan from IGCAS.
This research study will be published in the journal Nature today (February 9, 2022).
A superionic state, which is an intermediate state in between liquid and strong, commonly exists in the interior of planets. Utilizing high-pressure and high-temperature computational simulations based on quantum mechanics theory, researchers from IGCAS and the Center for High Pressure Science & & Technology Advanced Research (HPSTAR) found that some Fe-H, fe-o, and fe-c alloys transformed into a superionic state under inner core conditions.
In superionic iron alloys, light aspects become disordered and diffuse like a liquid in the lattice, while iron atoms remain bought and vibrate about their lattice grid, forming the strong iron framework. The diffusion coefficients of C, H, and O in superionic iron alloys are the exact same as those in liquid Fe.
” It is rather unusual. The solidification of iron at the inner core border does not change the mobility of these light elements, and the convection of light components is constant in the inner core,” said Prof. HE Yu, the very first and corresponding author of the research study.
One longstanding secret about the inner core is that it is quite soft, with quite low shear wave speed. It is the liquid-like elements that make the inner core soften,” said co-first author SUN Shichuan from IGCAS.
Extremely diffusive light aspects can affect seismic speeds, providing crucial hints for comprehending other secrets in the inner core. The anisotropic structure, seismic wave attenuations, and structural modifications of the inner core throughout past decades can be justified in the superionic design by considering the distribution and convection of these liquid-like elements in the inner core.
Recommendation: “Superionic iron alloys and their seismic speeds in Earths inner core” 9 February 2022, Nature.DOI: 10.1038/ s41586-021-04361-x.
Earths interior structure and superionic inner core. Credit: IGCAS
Earths core, the deepest part of our planet, is defined by exceptionally high pressure and temperature. It is made up of a liquid external core and solid inner core.
The inner core is formed and grows due to the solidification of liquid iron at the inner core border. The inner core is less dense than pure iron, and some light components are believed to be present in the inner core.
A joint research group led by Prof. HE Yu from the Institute of Geochemistry of the Chinese Academy of Sciences (IGCAS) has actually found that the inner core of the Earth is not a normal solid but is composed of a solid iron sublattice and liquid-like light elements, which is also known as a superionic state. The liquid-like light components are highly diffusive in iron sublattices under inner core conditions.