Microscopic dynamics of liquid aluminum oxide

Area of Science:

• Condensed Matter Physics
• Materials Science
• Physical Chemistry

Background:

• Understanding the dynamics of liquid materials at high temperatures is crucial for various industrial applications.
• Liquid aluminum oxide presents unique challenges due to its high melting point and complex behavior.
• Bridging the gap between atomistic and continuum theories requires experimental data on liquid dynamics.

Purpose of the Study:

• To investigate collective excitations in liquid aluminum oxide at high temperatures.
• To provide experimental constraints for theoretical models describing liquid behavior.
• To explore the transition between atomistic and continuum descriptions of liquids.

Main Methods:

• Utilized a containerless sample environment to handle high-temperature liquid aluminum oxide.
• Employed inelastic X-ray scattering (IXS) to probe collective excitations.
• Analyzed excitation spectra across a range of wave vectors (Q).

Main Results:

• Observed a distinct triplet peak structure in the excitation spectra at lower wave vectors (1-6 nm⁻¹).
• Identified a single quasi-elastic peak at higher wave vectors.
• High-Q spectra were accurately modeled by kinetic theory, while low-Q spectra necessitated a frequency-dependent viscosity.

Conclusions:

• The study provides the first experimental observation of collective excitations in liquid aluminum oxide.
• The results highlight the need for frequency-dependent viscosity in describing low-Q dynamics.
• This work offers critical experimental data for refining theories of liquid behavior at the atomistic-continuum interface.