Effect of Dopants on Σ3 (111) Grain Boundary in Diamond

Abstract

Extensive research has been conducted on electronic properties of metal‐doped diamond for electrochemical applications. The codoped diamond has emerged as an important strategy to enhance their performance and impart novel characteristics. In the present investigation, density functional theory calculations are used to envisage the structural, electronic, and elastic properties of nitrogen‐vacancy (N‐V) and silicon‐vacancy (Si‐V) defects at the Σ3 (111) grain boundary (GB) in diamond. Further, the Li and Na atoms are introduced as a dopant into these defective structures, referred as Σ3Li(N‐V), Σ3Na(N‐V), Σ3Li(Si‐V), and Σ3Na(Si‐V). The results reveal that the doped structures considered in the investigation are energetically and dynamically stable. The presence of defects (i.e., dangling bonds due to the presence of vacancies and dopants) at the Σ3 (111) GB significantly alters the overall electronic property of the diamond. The adsorption energies calculated for the doped systems range from −1.2 and 8.38 eV. The Σ3Li(N‐V) shows negative adsorption energy, indicating the tendency of lithium atom to adsorb exothermic onto the GB of Σ3N‐V, whereas, other adsorptions are endothermic in nature. The choice of dopant plays a substantial role in altering the properties of diamond, while the mechanical properties of the investigated Σ3 (111) diamond structures vary marginally.