High-resolution imaging and electron energy-loss studies of platelet defects in diamond

High-resolution electron microscopy, scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy have been used to study the structure and stoichiometry of 〈100〉{⅓00} platelet defects in type 1a diamond. It is shown that the platelets consist of one, two or at most three atomic planes having stoichiometry and/or spacings which differ from the diamond host. Whilst it proved impossible positively to locate nitrogen in the platelets, analysis of the energy-loss spectra showed that platelets consisting of four or more nitrogen planes would have been detected, placing an upper limit to their nitrogen content. STEM images obtained using zero-loss and 5 eV-energy-loss electrons showed that there are significant absorption processes associated with the partial dislocation which terminates the small (150 A diameter) platelets inside the diamond.