Regensburg 2004 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 4: Gl
äser II (gemeinsam FV DF/DY)

DF 4.4: Vortrag

Dienstag, 9. März 2004, 15:30–15:45, H23

Short-range order fluctuations and the boson peak in simulated amorphous NiZr — •M. Guerdane and H. Teichler — Institut für Materialphysik, Universität Göttingen

The boson peak is a striking feature in the vibration spectrum of glassy systems. We here present results from molecular dynamics simulations for Ni₃₀Zr₇₀, relating the boson peak of the system to local fluctuations in the short-range order. Analysis of the topology around Ni atoms in the system shows that Ni in the amorphous state on average has a coordination number <Z>=9, where in detail a mixture of perfect or slightly distorted trigonal prisms (TP, Z=9) or archimedean antiprisms (AAP, Z=10) and environments with Z=8 predominate. Both TP and AAP represent the basic structural units in the crystalline intermetallic compounds NiZr (B33-Type) and NiZr₂ (C16-Type) respectively. We show that the boson peak in the amorphous NiZr system is related to fluctuations in time between local environments of different coordination numbers Z.