Evolutionary Algorithm Directed Synthesis of Mixed Anion Compounds LaF₂ X (X=Br, I) and LaFI₂

Area of Science:

• Materials Science
• Solid-State Chemistry
• Computational Materials Discovery

Background:

• Mixed-anion compounds offer unique properties but are synthetically challenging.
• Rational design strategies are needed to accelerate the discovery of these materials.
• Lanthanum-based compounds are of interest for various applications.

Purpose of the Study:

• To explore the LaF3-LaX3 (X=Cl, Br, I) system for novel mixed-anion compounds.
• To predict new stable structures using ab initio methods.
• To synthesize and characterize predicted compounds, evaluating their properties.

Main Methods:

• Utilized ab initio structure searches based on evolutionary algorithms.
• Performed density functional theory calculations for structural prediction.
• Synthesized predicted compounds and characterized their crystal structures and ionic conductivity.

Main Results:

• Predicted novel mixed-anion compounds: LaF2X and LaFX2 (X=Br, I).
• Successfully synthesized LaF2Br and LaFI2 in predicted structures; LaF2I showed similar but distinct stacking.
• LaF2I demonstrated fluoride ion conductivity comparable to LaF3, with potential for enhancement.

Conclusions:

• Ab initio structure prediction accelerates the discovery of mixed-anion compounds.
• The synthesized compounds, particularly LaF2I, exhibit promising ionic conductivity.
• Ordered anion arrangements in layered structures are key for developing new functional materials.