Study on the Optical Properties and Lattice Thermal Conductivity of Ti2AlB2

In this paper, the optical properties and lattice thermal conductivity of Ti2AlB2 were studied by first-principles calculations. The real part of the dielectric constant, ε1, attains a significant value of 47.26 at 0.12 eV, indicating strong polarization capabilities and energy storage capacity. Regarding optical properties, Ti2AlB2 exhibits significant absorption peaks at photon energies of 4.19 eV, 6.78 eV, and 10.61 eV, and 14.32 eV, with absorption coefficients of 184,168.1 cm−1, 228,860.8 cm−1, 366,350.8 and 303,440.6 cm−1, indicating a strong absorption capacity. The loss function exhibits peaks at 19.80 eV and the refractive index reaches a maximum of 8.30 at 0.01 eV. Reflectivity is notably higher in the 0–5 eV range, exceeding 44%, which demonstrates excellent reflective properties. This suggests that Ti2AlB2 has potential as an optical coating material across certain frequency bands. The lattice thermal conductivity of Ti2AlB2 is obtained at 27.2 W/(m·K). The phonon relaxation time is greater in the low-frequency region, suggesting that phonons have a longer duration of action during the heat transport process, which may contribute to higher thermal conductivity. Although the phonon group velocity is generally low, several factors influence thermal conductivity, including phonon relaxation time and Grüneisen parameters. The high Grüneisen parameter of Ti2AlB2 indicates strong anharmonic vibrations, which may enhance phonon scattering and consequently reduce thermal conductivity. However, Ti2AlB2 still exhibits some lattice thermal conductivity, suggesting that the contributions of phonon relaxation time and group velocity to its thermal conductivity may be more significant. The unique optical properties and thermal conductivity of Ti2AlB2 indicate its potential applications in optical coatings and high-temperature structural materials.