First-Principles Investigation of Pressure-Induced Structural Phase Transition and Properties of CsPbF₃ Polymorphs

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Cesium lead fluoride (CsPbF3) is a material with potential applications.
• Understanding its behavior under high pressure is crucial for exploring new phases and properties.

Purpose of the Study:

• To investigate the high-pressure structural transitions of CsPbF3 polymorphs.
• To analyze the mechanical, electronic, and optical properties of these phases.
• To address the lack of reported data on the mechanical stability and optical properties of the R3̅c and Pnma phases.

Main Methods:

• First-principles calculations using the Vienna ab initio simulation package (VASP).
• Plane wave pseudopotential method within density functional theory (DFT).
• Computation of elastic constants, moduli, and electronic band structure.

Main Results:

• Identified pressure-induced transitions in CsPbF3 from Pm3̅m symmetry to R3̅c and Pnma phases.
• All three polymorphs (Pm3̅m, R3̅c, Pnma) are mechanically stable with wide band gaps (3-5 eV).
• Pm3̅m and R3̅c phases exhibit direct band gaps, while the Pnma phase has an indirect band gap.

Conclusions:

• This research provides novel data on the mechanical stability and optical properties of CsPbF3 polymorphs under pressure.
• The findings contribute to understanding CsPbF3's behavior and its potential for advanced technological applications.
• Sets the stage for future detailed studies on these polymorphs.