Raman scattering study on fractal structures in YSZ

Low-frequency Raman scattering spectra in yttria-stabilized zirconia (YSZ) were measured on several samples with different compositions. It is found that the frequency dependence of the Raman intensity can be represented by two straight lines with different slopes on a log-log scale. Since the slope in the lower-frequency region obeys a ω⁴ law, the region below the crossover frequency ω_co is assigned to the "phonon region". On the other hand, Raman spectra above ω_co cannot be explained by a Debye model, but can be interpreted in terms of a fracton model. The fractal and fracton dimensionalities are estimated in this system.