The Raman Spectrum and High Lattice Thermal Conductivity of Ternary Layered Boride Cr3AlB4

Abstract

The Raman spectrum and lattice thermal conductivity of the ternary layered boride Cr₃AlB₄  were investigated using first-principles methods in this study. The results of the electronic band structure indicate that Cr₃AlB₄  exhibits metallic properties. Cr₃AlB₄ also exhibits 9 Raman-active and 12 infrared-active modes. Low- and mid-frequency motions are dominated by Cr and Al displacements, whereas high-frequency modes arise chiefly from B-atom vibrations. The computed lattice thermal conductivity of Cr₃AlB₄ is 87.9 W/(m K); the phonon lifetime is long at low frequencies, while the overall group velocity remains modest. However, the effects of anharmonic vibrations are minimal, as indicated by a small Grüneisen parameter, and the anharmonic scattering rate is also low due to a limited weighted phase space. The elevated thermal conductivity of Cr₃AlB₄  arises from its compact crystal structure, strong covalent bonds, minimal anharmonic vibration effects, and fewer phonon scattering channels.