Mössbauer spectroscopy studies of57Fe in diamond

The sensitivity of Mössbauer probe nuclei to electric field gradients in their immediate environment in a host matrix has been utilised in several studies on57Fe or57Co implanted in diamond. Significant contributions to these studies were made by the early measurements by Hendrik de Waard and his co-workers. Recent investigations have continued with in-beam and ion implanted Mössbauer studies in natural and synthetic diamonds, and with current studies following57Mn implantation. A critical review of all the data has allowed components in the spectra due to interstitial and substitutional Fe to be identified and leads to the conclusion that high fractions of Fe at high-symmetry substitutional sites in diamond can be achieved either with implantation at high temperature or annealing above 1400 K. A comparison of the results obtained on different types of diamonds show that if diamond is indeed to play a significant role in future optoelectronic device fabrication then high-purity, CVD synthesised diamonds are required.