Density Functional Study of the Influence of Carbon Doping on the Aluminum-27 and Nitrogen-14 Electric Field Gradient Tensors in (10, 0) Single-Walled Aluminum Nitride Nanotube

Abstract

Density functional theory (DFT) study was performed to investigate the influence of carbon doping (C-doping) on the electric field gradient (EFG) tensors at the sites of aluminum-27 (²⁷Al) and nitrogen-14 (¹⁴N) nuclei in (10, 0) single-walled aluminum nitride nanotube (AlNNT). Two models of original and C-doped AlNNTs were optimized at first and then the EFG tensors were calculated in the optimized structures. The calculated EFG tensors were converted to measurable nuclear quadrupole resonance (NQR) spectroscopy parameters, quadrupole coupling constant (C_Q) and asymmetry parameter (η_Q). The calculated parameters in the original model reveal that the Al and N atoms located at the mouths of nanotube have the largest C_Q values revealing their remarkable role in AlNNTs. When C-doping occurs, the C_Q values of those nuclei directly bonding to C are significantly increased meaning that the active sites in the C-doped model are increased. The results also reveal that the Al and N play the basic and acidic agents roles, respectively, in AlNNT which is better observed in the C-doped model.