Total dynamic structure factor of icosahedral and As-quenched and relaxed glassy Pd58.8Si20.6U20.6 measured at 296 K |
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Authors: | J -B Suck H Bretscher H -J Güntherodt |
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Institution: | (1) Institut für Nukleare Festkörperphysik, Kernforschungszentrum Karlsruhe, Postfach 3640, D-7500 Karlsruhe, Federal Republic of Germany;(2) Institut für Physik, Universität Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland |
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Abstract: | The total dynamic structure factorsS(Q, ) of icosahedral, glassy Pd58.8Si20.6U20.6, and the crystallized sample have been determined at room temperature using inelastic scattering of cold neutrons (IN6 of ILL). In contrast to the static structure factorS(Q), where the long range bond orientational order (BOO) leads to pronounced diffraction peaks with finite half width, the dynamic structure factor shows little or no influence of the long range BOO on the atomic dynamics of icosahedral PdSiU in the range of frequencies (0.5![lE](/content/l84417q37057q673/xxlarge8806.gif) ![hstrok](/content/l84417q37057q673/xxlarge295.gif) ![ohgr](/content/l84417q37057q673/xxlarge969.gif) 25 meV) and momentum transfers Q(5 Q 30 nm–1 for inelastic scattering) investigated here. The wavelength-dependence of the atomic dynamics of icosahedral PdSiU is very similar to that of the metallic glass and is different from that of the crystallized sample. As for glassy PdSiU no well defined vibrational collective excitations are found as peaks in the inelastic part ofS(Q, ) of the icosahedral sample,-quite in contrast to theoretical expectations and to the dispersions of pronounced excitations determined under identical experimental conditions fromS(Q, ) of the crystallized sample. On structural relaxation of the metallic glass Pd58.8Si20.6U20.6 the largest amount of low energy modes is annealed out at lowest energy.Dedicated to Professor Harry Thomas on the occasion of his 60th birthday |
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