First principle investigation of Tb3+ activated Mg2SnO4 multicolor emitting phosphor: optical and thermodynamic properties under varying pressure

The current investigation delves into a comprehensive analysis of the structural, electronic, bandgap characteristics, optical, and thermodynamic attributes of a newly developed phosphor (Tb³⁺:Mg₂SnO₄), utilizing density functional theory (DFT) principles. Current research on phosphor materials often faces challenges in achieving stable multicolor emission with tunable properties suitable for advanced optoelectronic applications. In particular, there is a lack of theoretical insight into how rare-earth doping affects complex host lattices' optical, thermodynamic, and electronic behavior. The fundamental objectives of this study encompass unraveling the intricate capacity of Tb³⁺ doped Mg₂SnO₄ phosphor for adjustable color emissions in both its two-dimensional (2D) and three-dimensional (3D) configurations. The absence of imaginary frequencies in the phonon band structures confirms the dynamic stability of both phases. The findings of this study unveiled the compelling optical responsiveness of Tb³⁺:Mg₂SnO₄ across the 2D-Tb-Mg and 3D-Tb-Mg sites, giving rise to distinct orange and green emissions, respectively. Notably, this innovative phosphor exhibits a direct band gap of 0.3 and 1.5 eV for its 2D and 3D structures, which supports its potential for tunable light emission. The thermodynamic properties of Tb³⁺-doped Mg₂SnO₄ were calculated using the quasi-harmonic Debye model implemented via the Gibbs2 code. The results show that the Gibbs free energy decreases smoothly with increasing temperature, which confirms the thermodynamic stability of the material across a wide temperature and pressure range. This indicates the compound's suitability for high-temperature applications, such as in optoelectronic and LED devices. Our findings show that Tb³⁺ activated Mg₂SnO₄ is a multicolor-emitting (orange and green) phosphor and a potential candidate for electronic and optoelectronic applications. This particular variety of versatile color-tunable phosphors holds immense potential across an extensive array of applications within the realm of optoelectronic and solid-state lighting applications.