Structural, Electronic and Vibrational Properties of Al₄C₃

Abstract

Al 4 C 3 single crystals are synthesized by the reaction between SiC and aluminum and are structurally verified and analyzed by Raman and X-ray diffraction spectra. The optical absorption measurements of the Al 4 C 3 crystals indicated that the bandgap is about 2.3 eV, which surprisingly is much higher than the bandgap value from the literature. In order to elucidate the discrepancy between the new experimental results and the literature, an advanced ab initio based investigation on the structural, electronic and vibrational properties of the Al 4 C 3 is performed. Remarkably, the scGW approach arrived at an indirect band gap Γ ! L equal to 2.12 eV while the HSE06 calculated band gap was found even closer to the experimental value equal to 2.27 eV. In addition, the hole effective mass is found to be considerably high due to the flat nature of the valence band at the Γ, indicating low hole mobility. Moreover, phonon calculations indicated that the vibrations of the Al atoms contribute mostly on low frequency acoustic branches, while vibrations from C atoms have a stronger contribution to optical phonons.

Ultra‐Robust Flexible Electronics by Laser‐Driven Polymer‐Nanomaterials Integration

“…[ 33 ] Indeed, the low‐frequency Raman spectrum of LIMPc, in the inset of Figure 1a, shows the characteristic peaks from Al 4 C 3 , confirming the formation of this carbide phase. [ 34,35 ] This is an exciting result since aluminum carbide is an attractive reinforcement material for forming metal matrix composites, which are in high demand by modern aerospace, marine, and automobile industries. The Al 4 C 3 phase is lightweight, has a low thermal expansion, high thermal conductivity, stiffness, and strength.…”

“…While Al 2 O 3 is a dielectric, Al 4 C 3 is a semiconductor with a bandgap ranging from 1.3 to 2.4 eV. [ 35,40 ] EDX results (see inset in Figure 1i and Figure S6, Supporting Information) show that Al is present throughout the 20–30 µm of the laser‐induced composite (the LIMPc thickness depends on the initial metal film thickness and laser irradiation parameters). In contrast, XPS shows that after laser irradiation Al is mostly in its oxidized form with a sixfold increase of the oxide component (2p peak area) with respect to metallic Al (2p 3/2 and 2 p1/2 peaks), see Figure1 c–e and Figures S7 and S8, Supporting Information.…”

Grain Refinement of Cast Aluminum by Heterogeneous Nucleation Site Particles with High Lattice Matching

“…The crystal structure of Al 4 C 3 can be described as hexagonal which consists of alternating layers of Al 2 C and Al 2 C 2 along (0001) direction. 68) Since the lattice parameters of A1 4 C 3 phase were a = 0.334 nm and c = 2.500 nm, 69) M value with crystallographic orientation of ð0001Þ Al 4 C 3 parallel to (111) Al at RT is calculated to be 73.8 © 10 ¹3 . The lattice mismatch between the Al 4 C 3 and aluminum under this crystallographic orientation appears to be extremely large.…”