Optical studies of growth features on the surfaces of some diamonds

Part I of this thesis deals with a brief historical review on diamond together with the studies made on crystal growth with the existing information on diamond. Part II deals with the experimental techniques employed for the present investigation including an interference technique whereby, it has been shown for the first time, that very sharp multiple-beam interference fringes can be produced with a high power 3 mm. lens of numerical aperture 0.95. The optical conditions necessary to secure high definition in the fringes are discussed together with the arrangement used which can resolve a lateral extension about 0.7 and a depth of 50 A0. Volume elements as small as 5 x 10 cc. can be resolved. Part III deals with the optical studies of growth features on the octahedron faces of some diamonds. Some features of particular interest are described namely :-1 - A number of anomalies in trigons. These are discussed in detail.2 - An occasional mode of growth sheets is shown to operate on the octahedral faces of diamond which leads to the formation of six-sided growth features containing alternate angles of approximately 90[degrees] and 150[degrees]. It is shown that the edges of these are effectively parallel to the directions 431.These may possibly arise through intersections of (221) with (111)3 - A remarkable case of multiple linear processes has been observed on five faces of a well formed good octahedron. This has been well interpreted as due to crystallographic slip in diamond. Part IV deals with the microstructure on the dodecahedral faces of some diamonds. Some new surface structures are described. A mosaic structure exists. At least three main different structures for the (110) faces can possibly arise during the growth of diamond namely :-1 - Striated surfaces either smooth or coarse.2 - A network structure.3 - A parallelogram structure related to 2.These structures are described and discussed in detail.