A proposed structure for nitrogen impurity platelets in diamond

Abstract

Evidence on lattice displacements due to nitrogen platelets in diamond is reviewed. It is shown that interplanar spacings of a diamond containing platelets may differ in either sense from that of pure diamond, depending upon the index of the Bragg reflection. Structures previously proposed for substitutional nitrogen in diamonds are criticized. A platelet structure is proposed with six carbon and four nitrogen atoms per unit cell. With standard bond lengths it produces an expansion normal to the platelet of 1.18 Å, in accord with evidence from anomalous `spike' x-ray reflections. It also produces no density change in agreement with experiment.