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Energetika strukturních změn MoSi2
Káňa, Tomáš ; Legut, Dominik ; Šob, Mojmír
We employed ab initio calculations to investigate total energy profiles along the transformation paths connecting the C11b, C40 and C54 structures in MoSi2. The transformations were realized by change of the stacking sequence of the atomic planes. We found that the total energy profiles of the proposed paths have high energy barriers between end-point structures: 1.4 eV/f.u (f.u is the formula unit) for the C40-C54 path, 1.8 eV/f.u for the C11b-C40 path and finally 2.5 eV/f.u. for the C11b-C54 path.
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Ab initio study of phase stability in metals
Káňa, Tomáš ; Hüger, E. ; Šob, Mojmír
We employ ab initio calculations to study the behavior of total energy along the transformation paths between the hexagonal close-packed (hcp) structure and face-centered cubic (fcc) structure in Al, Co, Ni, Cu and Pd. We found one peculiar transformation path wit h extremely low energy barrier of only 0.010 eV/atom for Al, 0.020 eV/atom for Pd, 0.030 eV/atom for Cu, 0.033 eV/atom for Ni and 0.050 eV/atom for Co.
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Možné transformační dráhy spojující struktury C11b, C40 and C54 v MoSi2
Káňa, Tomáš ; Legut, Dominik ; Šob, Mojmír
We suggest three transformation paths between the ideal C11b , C40 and C54 structures of transition-metal disilicides. These three structures can be regarded as different stackings of identical planes of atoms. Each suggested transformation path consists in shifting these atomic planes in three directions. The shift of planes is described by one parameter p <0;1>. Along each path, we calculate the total energy of MoSi2 as a function of p. Our results confirm the structural order C11b → C40 →C54 in MoSi2. The C11b–C54 path exhibits the largest energy barrier, 2.5 eV/f.u (f.u. means the formula unit). The energy barrier of the C11b–C40 path is lower, 1.7 eV/f.u. and finally the energy barrier of the C40–C54 path is the lowest one, 1.4 eV/f.u.
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