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<p>In this study, we have systematically investigated the structural, electronic, elastic, optical, and thermoelectric properties of quaternary chalcogenide compounds ACu<sub>3</sub>TlSe<sub>4</sub> (A = Mg, Ca, Sr, Ba) using first-principles density functional theory (DFT). Structural optimization reveals a monotonic increase in lattice parameters and unit cell volume with increasing ionic radius of the A-site cation, accompanied by a gradual decrease in bulk modulus, indicating enhanced compressibility. Electronic band structure and density of states confirm semiconducting behavior for all compositions, with band gaps and orbital contributions tunable through alkaline-earth substitution. Charge density maps demonstrate evolving electron localization and bonding character, particularly near Se atoms, influenced by the size and electronegativity of the A-site elements. Elastic constant analysis confirms mechanical stability and ductile nature across the series, with increasing anisotropy and decreasing stiffness from Mg to Ba. Optical investigations highlight strong interband transitions, high static dielectric constants, and enhanced photoconductivity, especially in MgCu<sub>3</sub>TlSe<sub>4</sub>. Thermoelectric analysis reveals a compelling trend in which BaCu<sub>3</sub>TlSe<sub>4</sub> exhibits the highest figure of merit (ZT ≈ 0.85 at 1000&#xa0;K), making it a prime candidate for high-temperature energy harvesting applications. This comprehensive study demonstrates the significant role of A-site cation engineering in tuning the multifunctional properties of ACu<sub>3</sub>TlSe<sub>4</sub> compounds for future optoelectronic and thermoelectric devices.</p>

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ACu3TlSe4 (A = Mg, Ca, Sr, Ba): a comprehensive DFT analysis of physical properties

  • 期刊论文

  • 发表日期：

    2026年1月17日

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  • Taimoor Zahid,
  • Kiran Batool,
  • Jaber M. Asiri,
  • Muhammad Saeed,
  • Ma Shuangyi

摘要

In this study, we have systematically investigated the structural, electronic, elastic, optical, and thermoelectric properties of quaternary chalcogenide compounds ACu3TlSe4 (A = Mg, Ca, Sr, Ba) using first-principles density functional theory (DFT). Structural optimization reveals a monotonic increase in lattice parameters and unit cell volume with increasing ionic radius of the A-site cation, accompanied by a gradual decrease in bulk modulus, indicating enhanced compressibility. Electronic band structure and density of states confirm semiconducting behavior for all compositions, with band gaps and orbital contributions tunable through alkaline-earth substitution. Charge density maps demonstrate evolving electron localization and bonding character, particularly near Se atoms, influenced by the size and electronegativity of the A-site elements. Elastic constant analysis confirms mechanical stability and ductile nature across the series, with increasing anisotropy and decreasing stiffness from Mg to Ba. Optical investigations highlight strong interband transitions, high static dielectric constants, and enhanced photoconductivity, especially in MgCu3TlSe4. Thermoelectric analysis reveals a compelling trend in which BaCu3TlSe4 exhibits the highest figure of merit (ZT ≈ 0.85 at 1000 K), making it a prime candidate for high-temperature energy harvesting applications. This comprehensive study demonstrates the significant role of A-site cation engineering in tuning the multifunctional properties of ACu3TlSe4 compounds for future optoelectronic and thermoelectric devices.