Dresden 2003 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 4: Gl
äser Ib (gemeinsam FV DF/DY)

DF 4.1: Vortrag

Dienstag, 25. März 2003, 10:15–10:30, HSZ/403

Microscopic dynamics in binary oxide glasses — •Florian Kargl¹, Andreas Meyer¹, Anita Widmann¹, and Helmut Schober² — ¹Physikdepartment E13, TU München, 85748 Garching — ²Institut Laue Langevin, 38042 Grenoble, Frankreich

We present our recent results on quasielastic neutron scattering in sodium borate and sodium germanate melts. Sodium silicate (NS) melts exhibit a prepeak in the elastic structure factor around q = 0.9 Å⁻¹ [1]. Molecular dynamic simulations identify the prepeak with typical sodium-rich channel distances [2]. Sodium diffuses via these channels that are embedded in the SiO-matrix. Sodium borate and sodium germanate melts show no experimental indication for such a medium range order. Microscopic dynamics reveal a fast localized relaxation process that has not been observed in NS. The latter can be described within the framework of the mode coupling theory for viscous liquids.

[1] A. Meyer et al., Europhys. Lett. 59(5), 708-713 (2002)

[2] J. Horbach et al., Phys. Rev. Lett. 88(12), 125502 (2002)