First-Principles Investigation of Structural, Mechanical, Electronic and Optical Properties of Ba₂MReO₆ (M = Li, Na,...

Area of Science:

• Materials Science
• Solid State Physics
• Computational Chemistry

Background:

• Growing demand for efficient, stable, and eco-friendly materials for optoelectronic and photovoltaic applications.
• Double perovskite compounds are of significant interest for next-generation technologies.

Purpose of the Study:

• Systematically investigate structural, mechanical, electronic, and optical properties of Ba₂MReO₆ (M = Li, Na, K, Rb) double perovskites.
• Identify promising candidates for photovoltaic and solar-cell applications.

Main Methods:

• First-principles density functional theory (DFT) calculations.
• Structural optimization, thermodynamic and geometric stability analyses (formation energies, tolerance factors).
• Mechanical stability analysis, ab initio molecular dynamics (AIMD) simulations, band structure calculations (GGA-PBE, HSE06), optical property analysis.

Main Results:

• All compounds crystallize in cubic Fm3̅m symmetry and are thermodynamically, geometrically, and dynamically stable.
• Mechanical analysis indicates Ba₂LiReO₆ is stiffest, Ba₂RbReO₆ is most ductile.
• All compounds exhibit indirect band gaps, with HSE06 values ranging from 1.395 eV (Ba₂RbReO₆) to 2.236 eV (Ba₂LiReO₆).
• Optical properties show high polarizability, high absorption coefficients (~10⁶ cm^-1), and large optical conductivity in UV.

Conclusions:

• Ba₂RbReO₆, with a band gap of 1.395 eV and favorable optical characteristics, is the most promising candidate for photovoltaic applications.
• The investigated Ba₂MReO₆ double perovskites exhibit properties suitable for optoelectronic applications.