Berlin 2005 – wissenschaftliches Programm
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DF: Dielektrische Festkörper
DF 4: Poster
DF 4.3: Poster
Samstag, 5. März 2005, 08:30–16:30, Poster TU C
Structure and latticedynamics in Bismuth Triborate, BiB3O6 — •W.-D. Stein1, A. Cousson2, and M. Braden1 — 1II. Physikalisches Institut, Universität zu Köln — 2Laboratoire Léon Brillouin, C.E.A./ C.N.R.S., France
Bismuth Triborate, BiB3O6, is a particularly interesting material due to its outstanding non-linear optical properties [1,2], such as second harmonic generation and stimulated raman scattering. We are interested in the influence of the electron lone-pair on these effects, which is located at the bismuth-ion and was not included in the methods used to explain the measured features of optical nonlinearity [3]. We present a study of the structural properties with combined x-ray and neutron diffraction experiments at different temperatures. We find a temperature dependent shift of the bismuth ion with respect to the boron and oxygen ions which are not affected so much. This shift corresponds to a stronger localisation of this lone-pair. We also present our results of an inelastic neutron scattering experiment for determining the phonon dispersion curves. The effect of the lone-pair on the dispersion should be perceivable at the boundary of the brillouin zone, so that a neutron experiment was necessary to study their contribution.
[1] H. Hellwig et al. Solid State Comm. 109, 249 (1999)
[2] A. Kaminskii et al. Opt. Comm. 206, 179 (2002)
[3] D. Xue et al. Solid State Comm. 114, 21 (2000)