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<p>Quest for novel materials having extraordinary thermoelectric, and optoelectronic properties has increased dramatically with the development of optoelectronics and thermoelectrics. In this sense, one of the materials that has been studied the most by the scientific community is spinels. Using the WIEN2k and BoltzTrap software, this study examines the optoelectronic, mechanical, photo-catalytic, thermoelectric and thermodynamic properties of CoY<sub>2</sub> × <sub>4</sub> (X = S, Se) spinels. The materials under examination have cubic structures belonging to a specific space group. Mechanical and thermodynamic stability are suggested by the negative formation energies and the fulfilment of the Born stability conditions, respectively. The materials’ semiconducting properties are indicated by their spin-polarized band structure and density of states (DOS) that show a direct bandgap (E<sub>g</sub>). According to the optical properties, the static dielectric constants of CoY<sub>2</sub>S<sub>4</sub> and CoY<sub>2</sub>Se<sub>4</sub> are 5.8 and 6.4, respectively. These compounds have broad absorption spectra that is distributed over visible and ultraviolet regions, where ultraviolet region showing highest absorption. The materials’ ferromagnetic (FM) properties are revealed by the spin-dependent volume optimisation. A sizable local magnetic moment indicates that the compositions have magnetic properties due to the presence of Co ions. Furthermore, within the 300–800&#xa0;K, transport characteristics are analysed in connection to the increasing temperature. These materials’ thermal and electrical conductivities increase with respect to the temperature, and their elevated Seebeck coefficients range from 230 to 250 µV/K. Thermodynamic properties indicate that CoY<sub>2</sub>Se<sub>4</sub> consistently has the highest T*S and enthalpy, but also the most negative free energy, implying better thermal stability. To quantify photocatalytic activity for water splitting, CBM of spinels CoY<sub>2</sub>S<sub>4</sub> and CoY<sub>2</sub>Se<sub>4</sub> is found to be -3.55&#xa0;eV and − 4.16&#xa0;eV, whereas the VBM is at -5.74&#xa0;eV and − 5.94&#xa0;eV, respectively. Our findings suggest that the materials under investigation are promising choices for thermoelectric and energy conversion uses.</p>

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Study of mechanical, ferromagnetic, thermoelectric and thermo-dynamical stable ferrites CoY₂X₄ (X = S, Se): emerging candidates for energy conversion devices

  • 期刊论文

  • 发表日期：

    2026年4月2日

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  • Huda A. Alburaih,
  • M. Usama,
  • M. Aslam Khan,
  • N. A. Noor,
  • Shanawer Niaz,
  • Sohail Mumtaz,
  • A. Laref

摘要

Quest for novel materials having extraordinary thermoelectric, and optoelectronic properties has increased dramatically with the development of optoelectronics and thermoelectrics. In this sense, one of the materials that has been studied the most by the scientific community is spinels. Using the WIEN2k and BoltzTrap software, this study examines the optoelectronic, mechanical, photo-catalytic, thermoelectric and thermodynamic properties of CoY2 × 4 (X = S, Se) spinels. The materials under examination have cubic structures belonging to a specific space group. Mechanical and thermodynamic stability are suggested by the negative formation energies and the fulfilment of the Born stability conditions, respectively. The materials’ semiconducting properties are indicated by their spin-polarized band structure and density of states (DOS) that show a direct bandgap (Eg). According to the optical properties, the static dielectric constants of CoY2S4 and CoY2Se4 are 5.8 and 6.4, respectively. These compounds have broad absorption spectra that is distributed over visible and ultraviolet regions, where ultraviolet region showing highest absorption. The materials’ ferromagnetic (FM) properties are revealed by the spin-dependent volume optimisation. A sizable local magnetic moment indicates that the compositions have magnetic properties due to the presence of Co ions. Furthermore, within the 300–800 K, transport characteristics are analysed in connection to the increasing temperature. These materials’ thermal and electrical conductivities increase with respect to the temperature, and their elevated Seebeck coefficients range from 230 to 250 µV/K. Thermodynamic properties indicate that CoY2Se4 consistently has the highest T*S and enthalpy, but also the most negative free energy, implying better thermal stability. To quantify photocatalytic activity for water splitting, CBM of spinels CoY2S4 and CoY2Se4 is found to be -3.55 eV and − 4.16 eV, whereas the VBM is at -5.74 eV and − 5.94 eV, respectively. Our findings suggest that the materials under investigation are promising choices for thermoelectric and energy conversion uses.