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(a) Phonon frequencies at different pressures along the direction for MgTe. (b) Phonon frequencies of (open squares) and (solid squares) with pressure in MgTe. (c) Total energies with atomic displacements along the eigenvectors of mode at different pressures.
(a) The distortions of the phase projected along the  axis. In the plane, the movements of Mg cations are indicated by arrows perpendicular to the axis. The parameters of the atomic coordinates are given: the displacements along the axis for the nonmetal atoms (large spheres) and metal atoms (small spheres) are indicated as and , respectively. The gray (black) spheres represent their positions above (below) the plane, where Te (large gray spheres) and Mg (small gray spheres) are at (, , ) and (0.0, 0.0, 1.0), respectively, in the unit cell of phase. The Te–Te (Mg–Mg) zigzag chains along the  direction (b) and Mg–Mg zigzag chains along the  direction (c) in the phase of MgTe. At , the lattice parameters of phase are , , , and the Wyckoff sites (, 0.25, ) are occupied with , for Mg and , for Te, respectively.
(a) Enthalpy curves of , , and phases with respect to structure as a function of pressure. (b) Calculated volume as a function of pressure for (solid squares) and (solid stars) phases of MgTe. The experimental data for the phase are denoted by open squares.
(a) and (b) are the calculated Raman spectra of the and phases at , respectively. The intensities of modes in structure are too weak to be clearly visible with respect to those of the Ag modes and are labeled with the arrows.
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