2007/03/13 by Olena Gomonay, Gomonay, H. V., В. М. Локтев +1
Earth and Planetary Sciences · Physics and Astronomy · #High-pressure geophysics and materials #Seismic Waves and Analysis #Theoretical and Computational Physics
paper · pdf · doi:10.48550/arxiv.cond-mat/0703350
In the present paper we generalised a phenomenological model developed in \citegomo:2005 for the description of magnetostructural phase transitions and related peculiarities of elastic properties in solid oxygen under high pressure and/or low (below 40 K) temperature. We show that variation of all the lattice parameters in the vicinity of αβ-phase transition is due to both the shift of basal closed packed planes and appearance of the long-range magnetic order. Competition between these two factors from one side and lattice compression below Tαβ from another produces non monotonic temperature dependence of lattice parameter b (along monoclinic axis). Steep decrease of the sound velocities in the vicinity of Tαβ can be explained by the softening of the lattice with respect to shift of the close-packed planes (described by the constant K2) prior to phase transition point. We anticipate an analogous softening of sound velocities in the vicinity of αδ-phase transition and non monotonic pressure dependence of sound velocities in α-phase.