The lattice location of Ni in diamond: a theoretical study

Experiment unambiguously shows substitutional nickel is present in as-grown synthetic diamond where Ni is present in the solvent-catalyst. There is less convincing evidence for the presence of an interstitial species. We present the results of first-principles calculations of the properties of substitutional and interstitial Ni in diamond. The formation energy and mobility of the interstitial species suggest that nickel will be predominantly of the substitutional form. We also present possible models for the trigonal 1.404 eV optical centre correlated with the NIRIM-2 paramagnetic defect.