The Raman spectra and optical properties of ternary layered boride Ti3AlB4, Zr3AlB4, Hf3AlB4: An ab initio study

The crystal structure, band characteristics, vibration modes, Raman spectra, and optical properties of Ti3AlB4, Zr3AlB4, and Hf3AlB4 were studied in this paper. By investigating the crystal structure, it is evident that metal atoms Ti, Zr, Hf, and B atoms form a close-packed framework, while Al atoms occupy the interstitial sites, thereby enhancing structural stability. The band structure analysis indicates that these materials exhibit metallic characteristics. The density of states does not vanish at the Fermi level, and there is a crossover between different energy bands, which influences electronic transport and optical properties. The results of the infrared and Raman spectroscopy calculations indicate that these materials exhibit 24 vibrational modes at the Γ point, comprising 12 infrared-active modes and 9 Raman-active modes. The vibrational frequencies are closely linked to specific chemical bonds and atomic movements. Optical analysis reveals strong absorption across the infrared, visible, and ultraviolet spectra, accompanied by pronounced reflection over a specific wavelength range. Consequently, they have the potential to be utilized as coatings for spacecraft.