Research on the electronic properties of TiC/γ-Fe and TiB2/γ-Fe interfaces based on first-principles calculations

Abstract

Addressing the unclear understanding of the bonding mechanisms at the TiC/γ-Fe and TiB2/γ-Fe interfaces, the atomic structure, adhesive work, and electronic properties of the TiC (111)/Fe (111) and TiB2 (001)/Fe (111) interfaces were investigated using first-principles calculations. The results reveal that the C-terminated surface of TiC (111) and the B-terminated surface of TiB2 (001) exhibit high surface activity, facilitating their binding with the Fe (111) surface. The adhesive energy at the TiC (111)/Fe (111) interface is 13.04 J/m2, with a wetting angle of 41.32°, while at the TiB2 (001)/Fe (111) interface, the adhesive energy and wetting angle are 6.08 J/m2 and 74.69°, respectively. TiC demonstrates better wettability and stronger binding strength with γ-Fe surface. At the interface, the C-p orbitals and B-p orbitals hybridize with Fe-d orbitals to form bonds. The population of Fe-C bonds and Fe-B bonds is 0.46 and 0.02, respectively, indicating that Fe-C bonds exhibit covalent characteristics, while Fe-B bonds display ionic characteristics, with Fe-C bonds being stronger than Fe-B bonds. Statistical analysis of charge distribution and charge difference reveals electron accumulation near C and B atoms at the interface. Moreover, the electron transfer at the TiC (111)/Fe (111) interface is significantly greater than that at the TiB2 (001)/Fe (111) interface, which is the fundamental reason for the higher binding strength at the TiC (111)/Fe (111) interface.