Europhys. Lett.
Volume 67, Number 5, September 2004
Page(s) 793 - 799
Section Condensed matter: structure, mechanical and thermal properties
Published online 01 August 2004
Europhys. Lett., 67 (5), pp. 793-799 (2004)
DOI: 10.1209/epl/i2004-10120-y

Experimental evidence for the bimodal character of the vibrational spectrum of Zintl-type liquids

S. Jahn and J.-B. Suck

Institute of Physics, Materials Research and Liquids, TU Chemnitz 09107 Chemnitz, Germany

(Received 19 April 2004; accepted in final form 21 June 2004)

Cold neutron inelastic scattering is used to study the atomic dynamics in liquid $\chem{Rb}$ x $\chem{Sb}$ 1-x alloys. In this binary system, the type of interaction can be varied continuously by changing the composition. Around equiatomic composition, where the influence of covalent bonds is expected to be largest, the vibrational spectrum is composed of two modes, one at low frequencies that is assigned to vibrations of the anions against the cations, and a high-frequency mode that is associated with the eigenfrequencies of covalently bonded $\chem{Sb}$- $\chem{Sb}$ chains. The bimodal vibrational spectrum, observed for the first time in a Zintl-type system, is consistent with results from recent ab initio molecular-dynamics simulations.

61.25.Mv - Liquid metals and alloys.
63.50.+x - Vibrational states in disordered systems.
61.12.Ex - Neutron scattering (including small-angle scattering).

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