Electronic Structure and Core Spectroscopy of Scandium Fluoride Polymorphs

Area of Science:

• Materials Science
• Solid State Physics
• Computational Chemistry

Background:

• Scandium fluoride (ScF₃) is crucial for Al-Sc alloy production, yet its properties remain incompletely understood.
• A comprehensive understanding of ScF₃'s structural, energetic, and electronic characteristics is vital for optimizing its industrial applications.

Purpose of the Study:

• To computationally predict and analyze the stability and electronic structure of six ScF₃ polymorphs.
• To compare theoretical findings with experimental X-ray absorption spectra (XAS) for validation.
• To elucidate the electronic origins of spectral features and excitonic effects in ScF₃.

Main Methods:

• Utilized first-principles calculations based on Density Functional Theory (DFT).
• Employed the Bethe-Salpeter equation (BSE) for advanced electronic structure calculations.
• Performed X-ray absorption spectroscopy (XAS) using high-energy-resolution fluorescence detection.

Main Results:

• Identified similarities in formation energies, charge density, and electronic properties (band gaps, density of states) across ScF₃ polymorphs.
• Observed analogous behavior between low- and high-temperature phases, suggesting a lattice rotation mechanism for phase transition.
• Computational XAS results align well with experimental measurements, confirming the presence of dominant ScF₃ polymorphs.

Conclusions:

• The study provides microscopic insights into ScF₃ polymorphs, crucial for Al-Sc alloy development.
• DFT and BSE calculations accurately predict ScF₃ properties and spectral features.
• Experimental data suggest potential defects or metastable phases in the analyzed ScF₃ sample.