Pressure‐Tunable Multifunctionality in Cubic Fluoroperovskites CsZnF ₃ and CsHgF ₃ : A Comprehensive DFT Study of Structural, Electronic, and Optome

ABSTRACT

In this study, we comprehensively discussed a density functional theory (DFT) investigation of pressure effects (0–40 GPa) on structural, mechanical, electronic, thermal, optical, and piezoelectric properties of cubic fluoroperovskites CsZnF ₃ and CsHgF ₃ . It is found that both materials are classified as ductile, semiconductor, and nonmagnetic compounds, which maintain structural and mechanical stability under high pressure. The band gap value widens with an increase in pressure. The carrier effective masses decrease significantly under compression, suggesting enhanced charge transport and a preferable n‐type conductivity predisposition. In thermal properties, materials have shown resistance to withstand extreme temperatures that increases directly with pressure. Optical analysis reveals pressure‐tunable refractive indices (n (0)  =  1.27–1.42) and strong UV dispersion (n(ω) > 2.2), while the internal strain parameter ξ identifies CsHgF ₃ as a potential piezoelectric candidate under symmetry‐lowering conditions at pressures (0–20 GPa). The piezoelectric response shows two distinct behaviors in the studied materials. This response offers a balanced combination of stability and tunability for both materials, making them suitable for high‐pressure environments. These findings establish CsZnF ₃ and CsHgF ₃ as multifunctional wide‐band gap semiconductors with pressure‐adaptable properties for high‐pressure optoelectronic, piezoelectric, and magnetoresistive technologies.