T2-MgAl2C2 monolayer: First-principles insights into its structural, elastic, and optoelectronic properties
Micro and Nanostructures, cilt.218, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 218
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.micrna.2026.208812
- Dergi Adı: Micro and Nanostructures
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Anahtar Kelimeler: Chemical bonding, Elastic properties, First-principles calculations, Indirect-to-direct transition, Optoelectronic properties, T2-MgAl2C2 monolayer
- Ankara Üniversitesi Adresli: Evet
Özet
We present a first-principles study of the structural, elastic, electronic, and optical properties of the T2-MgAl2C2 monolayer. The proposed Al–C–Mg–C–Al sheet is found to be energetically feasible and dynamically stable, with an exfoliation energy of 365 meV/atom and no imaginary phonon modes. Its in-plane elastic response is isotropic, with a Young's modulus of about 192.37 N/m, indicating good mechanical robustness for a two-dimensional semiconductor. Electronic-structure calculations reveal that dimensional reduction from bulk to monolayer drives an indirect-to-direct band-gap transition, yielding a direct Γ–Γ gap of 1.61 eV at the HSE06 level, compared with the indirect 2.56 eV gap of the bulk phase. The band-edge states are dominated by C-2p orbitals in the valence region and Al-3p/Mg-3p orbitals in the conduction region, while charge analysis indicates polar-covalent Al–C bonding with ionic contribution from Mg. The monolayer also exhibits a relatively low work function of 3.72 eV and pronounced in-plane optical absorption across the visible and ultraviolet ranges, with visible-region peaks at 2.1, 2.4, and 2.9 eV. These results identify T2-MgAl2C2 as a stable direct-gap 2D semiconductor with attractive optoelectronic characteristics.