Artem Chanyshev

Methane is one of the most abundant hydrocarbon molecules in the universe and is expected to be a significant part of the icy giant planets (Uranus and Neptune) and their satellites. Ethane is one of the most predictable products of chemical reactivity of methane at extreme pressures and temperatures. In spite of numerous experimental and theoretical studies, the structure and relative stability of these materials even at room temperature remains controversial. We have performed a combined experimental and theoretical study of both methane and ethane up at high pressures up to 120 GPa at 300 K using x-ray diffraction and Raman spectroscopy and the ab-initio evolutionary algorithm, respectively. In the case of methane we have successfully solved the structure of phase B by determining the space group and the positional parameters of carbon atoms, and by completing these results for the hydrogen positions using the theoretical calculations. The general structural behavior under pressure and the relation between phase B and phases A and pre-B will be also discussed. For ethane we have determined the crystallization point, for room temperature, at 1.7 GPa and also the low pressure crystal structure (Phase A). This crystal structure is orientationally disordered (plastic phase) and deviates from the known crystal structures for ethane at low temperatures. Moreover, a pressure induced phase transition has been indentified, for the first time, at 18 GPa to a monoclinic phase III, the structure of which is solved based on a good agreement of the experimental results and theoretical predictions. We have determined the equations of state of methane and ethane, which provides a solid basis for the discussion of their relative stability at high pressures.

Uranus

Monoclinic crystal system

Crystal (programming language)

10.1107/s2053273314092420

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Citations (2)

Carbonate–Iron Interaction: Kinetic Approach for Carbonate Subduction Down to the Mantle Transition Zone

AGU Fall Meeting Abstracts (2015)

Naira Martirosyan Takashi Yoshino Anton Shatskiy Konstantin D. Litasov Artem Chanyshev

Source

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Temperature-induced oligomerization of polycyclic aromatic hydrocarbons at ambient and high pressures

Scientific Reports (2017)

Artem Chanyshev Konstantin D. Litasov Yoshihiro Furukawa К. А. Кох Anton Shatskiy

Temperature-induced oligomerization of polycyclic aromatic hydrocarbons (PAHs) was found at 500-773 K and ambient and high (3.5 GPa) pressures. The most intensive oligomerization at 1 bar and 3.5 GPa occurs at 740-823 K. PAH carbonization at high pressure is the final stage of oligomerization and occurs as a result of sequential oligomerization and polymerization of the starting material, caused by overlapping of π-orbitals, a decrease of intermolecular distances, and finally the dehydrogenation and polycondensation of benzene rings. Being important for building blocks of life, PAHs and their oligomers can be formed in the interior of the terrestrial planets with radii less than 2270 km.

Ambient pressure

Bar (unit)

10.1038/s41598-017-08529-2

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Citations (34)

Effect of water on the magnesite–iron interaction, with implications for the fate of carbonates in the deep mantle

Lithos (2019)

Naira Martirosyan Anton Shatskiy Artem Chanyshev Konstantin D. Litasov Ivan V. Podborodnikov

Peridotite

Mineral redox buffer

Wüstite

Magnesite