We compare within an unifying formalism the dynamical properties of modulated and composite aperiodic (incommensurate) crystals.
We discuss the concept of inner polarization and we define an inner polarization parameter β that distinguishes between different
acoustic modes of aperiodic crystals. Although this concept has its limitations, we show that it can be used to extract valuable
information from neutron coherent inelastic scattering experiments. Within certain conditions, the ratio between the dynamic
and the static structure factors at various Bragg peaks depends only on β. We show how the knowledge of β for modes of an
unknown structure can be used to decide whether the structure is composite or modulated. The same information can be used
to predict scattered intensity within unexplored regions of the reciprocal space, being thus a guide for experiments.
Received 9 June 2002 Published online 14 October 2002
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ID="a"e-mail: Ovidiu.Radulescu@univ-rennes1.fr 相似文献
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