Isostructural transition in bcc Zr induced by the peculiarities of the lattice dynamics under pressureстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 1 апреля 2017 г.
Аннотация:The peculiarities of the atomic displacements corresponding to the longitudinal and transverse vibrations with wave vector k=23[111] in bcc zirconium are considered. It is shown that the three parts, which substantially differ in the lattice dynamics character, can be separated out in the region of existence of the bcc phase. Namely, at low pressures, the bcc lattice may only be dynamically stable; at high pressures, the ordinary bcc structure, which is characterized by a slight anharmonicity of the longitudinal L mode and small atomic displacements near the equilibrium positions in the bcc lattice, is realized. At intermediate pressures, prolonged vibrations near the equilibrium atomic positions are periodically interrupted by changes in the spatial orientation of the bcc lattice, which occur through a “virtual” ω phase. The equilibrium lines of the isostructural transitions connected with different characters of the bcc lattice dynamics are defined in the P−T phase diagram.