Investigation of Dynamical Scaling in a Mutually Self-Similar Series of Base-Catalyzed Aerogels

The phonon-fracton crossover in a series of fractal aerogels of well-defined microstructure is investigated for the first time. Results of small-angle neutron scattering combined with simulations establish the mutual self-similarity of the series and its fractal dimension D ≃ 1.7. Brillouin scattering is used to determine the fracton dimension related to tensorial elasticity, ≃ 1.1. Combined with Raman and neutron spectroscopic data, this allows to derive a consistent picture of dynamical scaling in relation with the structure of these materials.