Beneath their placid exteriors, the internal mechanisms of celestial bodies such as Uranus and Neptune are characterized by profound turbulence.
Immense pressures, manifold beyond terrestrial sea-level benchmarks, coupled with temperatures reaching thousands of degrees, give rise to remarkably peculiar substances.
A recent scientific publication from the Carnegie Institution, featured in Nature Communications, elucidates a novel state of matter potentially prevalent in these extreme cosmic locales – a phase designated as “quasi-1D superionic.”
It has long been understood that these ice giants are not composed of conventional “ices” as commonly conceived on Earth. Instead, their composition comprises a fervid, dense admixture of water, ammonia, and methane.
However, the laboratory replication of conditions necessary to generate such a slurry presents formidable challenges. It would necessitate pressures in the terapascals range at temperatures sufficiently elevated to compromise most containment vessels.
Typically, scientific inquiry in this domain relies on computational modeling, particularly a methodology known as “Synthetic Uranus,” which emulates the environment of our solar system’s seventh planet, including its characteristic pressure and thermal conditions.
Prior compositional investigations established that commonplace molecules, such as methane, undergo dissociation under these conditions, fragmenting into hydrogen-rich materials alongside carbon allotropes like diamond, typically around 95 gigapascals.
Yet, even these simulation approaches exhibit limitations, becoming less reliable at even greater pressures.
To address this deficiency, the current research adopts a first-principles approach, leveraging quantum mechanical principles to construct the complete environmental matrix – to the extent permitted by quantum mechanical modeling capabilities.
According to this simulated framework, at pressures exceeding 1100 GPa, carbon and hydrogen amalgamate to form a stable compound, albeit one exhibiting a highly unconventional structural arrangement.
At these extreme pressures, the carbon atoms coalesce into a rigid, crystalline lattice characterized by a chiral helical configuration – essentially, a microscopic, spiraling staircase.
The truly remarkable phenomenon emerges upon the application of thermal energy. Ordinarily, elevated temperatures would transition such a lattice into a liquid state, permitting unimpeded atomic movement.
However, in certain other substances, such as water, increased heat causes one atomic component (oxygen, in water’s case) to maintain a crystalline solid structure while the other component (hydrogen) begins to flow freely. This is recognized as a “superionic” state.
Within the temperature range of 1000 to 3000 Kelvin, the newly identified CH compound enters a superionic state, but with a distinct characteristic. Rather than oxygen forming the crystalline framework, as observed in water, this lattice is constructed from carbon atoms.
The hydrogen atoms, while confined by the carbon lattice, exhibit superionic diffusion along the helical axis (the z-axis) in conjunction with rotational movement within the transverse (xy) plane.
These hydrogen atoms are capable of facile propagation along the helical pathway but demonstrate a propensity for rotation rather than translation in orthogonal directions.
This predominantly unidirectional mobility, coupled with two-dimensional rotational behavior, has led researchers to classify it as a hybrid form of “diffusional dimensionality” – representing the world’s inaugural quasi-1D superionic state.
While theoretically sound, the practical implications of this discovery are significant. A primary consequence is the material’s anisotropic properties, meaning its characteristics vary depending on the measurement orientation.
For instance, the substance exhibits superior thermal and electrical conductivity along the “staircase” axis, while demonstrating considerably lower conductivity in the perpendicular directions. Furthermore, despite the presence of mobile, positively charged hydrogen atoms, electrical conductivity appears to remain predominantly governed by electron movement.
On a macroscopic level, this finding contributes to hypotheses concerning the anomalous magnetic fields observed in Neptune and Uranus. Conventional models attribute their oblique magnetic fields to an assumption of uniform thermal and electrical conductivity across the hot, superionic ices.
However, the emergence of this novel quasi-1D superionic phase challenges that premise, potentially offering a more accurate alignment with empirical data obtained from these planets.
It is acknowledged that a fundamental carbon-hydrogen composite represents a significant oversimplification of the intricate chemical and thermal dynamics operative within the cores of these planetary bodies.
Nevertheless, the very capacity to model and comprehend the putative behavior of some of these materials in their native environments underscores the vast potential for planetary science to continually illuminate the workings of the cosmos.
This article was originally published by Universe Today. Read the original article.
