کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1483319 1510534 2007 5 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Atomic dynamics in different regions of the potential energy surface
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد سرامیک و کامپوزیت
پیش نمایش صفحه اول مقاله
Atomic dynamics in different regions of the potential energy surface
چکیده انگلیسی

The atomic dynamics in two (bulk) metallic glasses, Ni40Pd40P20 and Zr55Cu30Al10Ni5, were investigated by neutron inelastic scattering in different regions of the potential energy landscape, which are reached by slow cooling the bulk glasses and by hyper-quenching the same alloys. The results prove that the atomic dynamics depends also on the fictive temperature, i.e. the region of the potential energy surface, in which the glass is frozen in. Obviously the shapes of the basins or inherent structures are not the same everywhere on the potential energy surface, and the glass with a higher fictive temperature has more low energy modes than has the same glass with a lower fictive temperature. As results from computer simulation have suggested already, on moving to regions of lower mean potential energy (aging), part of theses low energy modes are transferred to the energy region of the calculated Debye cut-off energy. The difference between the vibrational entropies, calculated from the generalized vibrational density-of-states, which have been determined for both fictive temperatures, shows that the contribution from the vibrational entropy to the total entropy change, when moving through the potential energy landscape, is small for the two metallic glasses investigated. Structural relaxation of the hyper-quenched glass removes part of the additional low energy modes, but quantitatively possibly only at the low and perhaps also at the high-energy limit of the density-of-states. The wavelength dependence of the dynamics suggests that the additional low energy modes in the glass with the higher fictive temperature are not dominated by extended but more likely by localized modes.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Non-Crystalline Solids - Volume 353, Issues 32–40, 15 October 2007, Pages 3177–3181
نویسندگان
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