Interpretation of x-ray and neutron diffraction patterns for liquid and amorphous yttrium and lanthanum aluminum oxides from computer simulation

Simulation models, based on an ionic description of closed-shell species and which incorporate many-body polarization effects, are derived for both yttrium and lanthanum aluminates using physically transparent mixing and scaling arguments. Three compositions (20%Y₂O₃/80%Al₂O₃, 25%Y₂O₃/75%Al₂O₃, and 25%La₂O₃/75%Al₂O₃) are studied in detail. The models are validated by direct comparison with the recently determined x-ray and neutron diffraction patterns. The complementary nature of the two diffraction patterns is shown to be highly important for effective model validation. The success of the models in reproducing the experimental scattering patterns allows the breakdown into the partial structure factors, and the corresponding real-space functions, to be fully understood. Significant features in the total scattering functions are identified and attributed to specific ion spatial correlations in a manner not possible using the total scattering function information only. Subtle differences in the real-space structure as a function of composition are analyzed and discussed in relation to possible polyamorphic behavior.