Correlation of light scattering and molecular dynamics in superionic Ba1-xLaxF2+x

The squares of the Brillouin frequencies (Deltaomega(B))(2) of the LA mode in the [100] direction related to the Cl, elastic constant show a linear decrease with temperature followed by significant deviations that occur above the corresponding transition temperatures (T-c), being at 850, 800, 970, 950 and 920 K for samples with x = 0.05, 0.1, 0.2, 0.3 and 0.5, respectively. The Raman linewidths show linear increases with temperature followed by rapid increases around the same temperatures at which the elastic constants start to show marked decreases. The complementary studies using Molecular Dynamics show that the diffusion coefficients start to increase markedly around the same temperatures observed experimentally.