Octahedral Tilt-Driven Phase Transitions in BaZrS₃ Chalcogenide Perovskite

Area of Science:

• Materials Science
• Solid-State Physics
• Computational Chemistry

Background:

• Chalcogenide perovskites offer lead-free alternatives for energy applications.
• Barium Zirconium Sulfide (BaZrS3) is noted for its stability and optoelectronic properties.
• Phase transitions in BaZrS3 are not well understood, with most studies at ambient conditions.

Purpose of the Study:

• To investigate the temperature and pressure-dependent phase transitions of BaZrS3.
• To explore the material's dynamics beyond ambient conditions.
• To provide a predictive model for BaZrS3 phase behavior.

Main Methods:

• Utilized a machine learning interatomic potential.
• Trained the potential using hybrid density functional theory data.
• Simulated BaZrS3 dynamics across various temperatures and pressures.

Main Results:

• Identified a first-order phase transition from orthorhombic to tetragonal (I4/mcm) at 610 K at 0 Pa.
• Discovered a second-order transition from tetragonal to cubic (Pm3m) at 880 K at 0 Pa.
• Found the tetragonal phase is more stable at higher pressures and temperatures.

Conclusions:

• The study elucidates the complex phase diagram of BaZrS3.
• Results are validated against experimental data, predicting X-ray diffraction patterns.
• Provides crucial data for optimizing BaZrS3 in photovoltaic and thermoelectric devices.