Imperfections in the structure of cobalt II. Mathematical treatment of proposed structure

The close-packed structures are made by piling up close-packed planes of atoms in three different relative positions. In proper hexagonal closepacking only two of the positions are used. The intensity of reflexion of X-rays is calculated for a structure which usually follows the hexagonal scheme, but has occasional faults introducing the third position. It is shown that this model gives a satisfactory explanation of the measured integral breadths of certain reflexions from hexagonal cobalt. The affected reflexions with l even are broadened more than those with l odd. The total intensity of the reflexions is not greatly changed. The frequency of faults in the specimen investigated by Edwards & Lipson is calculated, and is found to be, on the average, about one in every ten planes.