Mekhanobr Engineering JSC (Russia):

Zuev V. V., Leading Researcher, Doctor of Geology and Mineralogy, office@mekhanobr.spb.ru

Additional arguments are presented in support of the Earth's inner core main phase composition (Fe0,9Ni0,1), structure (body-centered cubic lattice with elementary cell parameter a₀ = 2.49  Å) and anticipated properties. New hypothesis on possible cobalt and nickel entry into the Earth's inner core central part as separate phases — homoatomic covalent crystals with CN = 9 and CN = 10 of 9-valent (Co) and 10-valent (Ni) elements, is formulated and substantiated. The formation conditions (Р = 265 GPa and Р = 320 GPa), as well as unique energy and physical parameters of these phases, significantly exceeding those of Fe(VIII)_0,9Ni(VIII)_0,1 main phase, whose content in the inner core reaches 90 %, are discussed. Contents of phases Co(IX) and Ni(X), according to preliminary estimates, amount to 9 % and 1 %, respectively. Though the presence of three phases from Fe-Co-Ni elements in hypervalent states in the Earth's inner core seems quite real and natural, yet this hypothesis requires further substantiation and support. Applied relevance of this article consists in justification of probability of existence (and, in prospect, development) of new mineral substances that may significantly exceed diamond and advanced ultra-hard materials in hardness

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