The Hydride Systems and Peculiarities of Hydrogen Solubility in these Structures
Theoretical investigation on the solubility of C-impurity in AB and AB3 alloys with hexagonal close-packed lattices of different structures has been carried out by the method of configurations in approaching the pair interaction of the nearest atoms. It is supposed that impurity atoms are located in octahedral and tetrahedral interstitial sites. The solubility dependence on alloy composition, temperature and order parameter has been defined. Comparison of the theoretical results with experimental data on the concentration and temperature dependence of hydrogen solubility shows good agreement between theory and experiment for PdPt–H, FeV–H, PdNi–H, Ni3Fe–H alloys. The theoretical calculation of hydrogen solubility in ordering bcc and fcc crystals of fullerites has been performed by the method of average energies and configuration method, i.e., taking into consideration the possibility of realization of different configurations of C60, C70 fullerenes around interstitial sites of various types, under the assumption of geometrical ideality of crystal lattices, with regard to the ordering of C60, C70 fullerenes on lattice sites and hydrogen atoms arrangement in interstitial sites of different types. The equilibrium concentrations of hydrogen atoms in interstices of all types and then the total solubilities of hydrogen in bcc and fcc fullerites have been found from conditions of free energies minimization. The dependences of hydrogen solubilities in bcc and fcc fullerites on temperature, fullerite composition, long-range order, hydrogen atoms activity, and energetic constants have been ascertained.
KeywordsInterstitial Site Interstitial Atom Atomic Order Hydrogen Solubility Interstitial Impurity
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