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DY: Dynamik und Statistische Physik

DY 29: Gl
äser II (gemeinsam FV DF/DY)

DY 29.7: Vortrag

Dienstag, 12. März 2002, 16:25–16:40, H23

Lattice Dynamics of Crystalline and amorphous Na-phosphates — •Nikolay Zotov¹, Armin Kirfel¹, Felix Reinauer², and Robert Glaum² — ¹Mineralogisch-Petrologisches Institut, University Bonn, Poppelsdorfer Schloss, 53115 Bonn — ²Institute of Inorganic Chemistry, University Bonn, Gerhard-Domagkstr. 1, 53121 Bonn

Phosphate glasses are technologically important materials used in a variety of applications. But the understanding of their vibrational properties is still on a rather empirical level. Theoretical calculations are very scarce [1]. Therefore, it is importnat to investigate quantitatively the character of the vibrational modes of crystalline and glassy phosphates. We have performed lattice dynamics calculations of crystalline sodium mata-, pyro- and orthophosphates using valence as well as BMH-type potentials and compared with measured Raman spectra. The optical representations and the symmetry of the IR/Raman active phonons were derived using factor group analysis. Theoretical Raman intensities were calculated using the bond-polarizability approximation[2]. Band assignment of the Raman peaks was made and used to interpret the broadening of the Raman spectra of Na-metaphosphate glass. Financial support by the DFG (SFB 408) is gratefully acknowledged. [1] T. Uchino, T. Yoko, J. Non-Crystalline Solids 263-264 (2000) 180 [2] N. Zotov, I. Ebbsjo, D. Timpel, H. Keppler, Phys. Rev. B 60 (1999) 6383