First-principles investigation of Co2+ and Mn2+ doping in Mg2SnO4: Structural, electronic, optical, thermodynamic, and mechanical properties for advanced phosphor applications

In this study, we investigated the structural, electronic, optical, thermodynamic, and mechanical properties of Co 2+ and Mn 2+ -doped Mg 2 SnO 4 phosphors using first-principles calculations. Our results reveal that Co 2+ doping induces semimetallic behavior, while Mn 2+ doping leads to semiconducting properties with a band gap of 0.55 eV. The introduction of Mn 2+ introduces defect states below the conduction band, resulting in n-type conductivity in both spin states. Mn 2+ -doped Mg 2 SnO 4 exhibits exceptional luminescent properties, owing to its small band gap, making it a promising candidate for advanced phosphor applications and optical devices. We also analyzed the optical properties, including dielectric reflection, reflectivity, refractive index, and absorption coefficient, revealing their dependence on photon energy and the electron energy loss spectrum. Additionally, we applied the quasi-harmonic Debye model to calculate key thermodynamic properties, such as Gibbs free energy, Debye temperature, entropy, enthalpy, and thermal expansion coefficient across a range of temperatures (0–1200 K) and pressures (0–10 GPa). The results also provide insights into the interdependence of these thermodynamic parameters under varying conditions. Lastly, our analysis of the mechanical properties indicates that both doped compounds exhibit mechanical stability and ductility, with relatively low stiffness, highlighting their potential for optoelectronics applications, especially in LEDs. • Co ²⁺ induces semimetallicity, Mn ²⁺ yields n-type semiconducting • Mg ₂ SnO ₄. Mn ²⁺ -doped Mg ₂ SnO ₄ has 0.55 eV bandgap, ideal for LEDs and optoelectronics. • Optical traits vary with photon energy: dielectric, reflectivity, absorption. • Pressure–temperature studies show Mg ₂ SnO ₄ ’s thermal stability for devices.