Research of tungsten-doped diamond: First-principles studies

Tungsten-doped high-density carbon (W-doped HDC) is a critical target material in nuclear fusion experiments. However, the microscopic structure of W-doped HDC remains insufficiently explored. Given that the diamond phase is a key component of HDC, the density functional theory (DFT) has been employed in this work to investigate the behavior of tungsten doping in diamond, providing insights into W incorporation in HDC. The key properties of tungsten in diamond, such as the formation energy in the bulk phase, the adsorption energy on the surface, the influence of nitrogen and oxygen elements on surface adsorption, the migration energy on the surface, and the formation energy in different carbon layers, are calculated. The significant atomic radius difference between tungsten and carbon causes substantial lattice mismatch, leading to high formation energy for tungsten doping in diamond bulk phase, which indicates doping difficulty. Additionally, the effect of carbon vacancies on tungsten doping is explored, and the results indicate that the suitable carbon vacancies can significantly reduce the formation energy, thus promoting tungsten doping in diamond.