Defect Structure of Synthetic Diamond and Related Phases

Abstract

AbstractThis paper examines the relationship between the lattice defects and crystallization process of synthetic diamonds. Diamonds synthesized by high pressure, high temperature methods as well as diamonds vapor deposited under metastable conditions are considered. High pressure crystals precipitated from Ni or Co solutions contain inclusions of metastable carbides and metal atoms distributed throughout a small fraction of the octahedral holes in the diamond lattice.Diamonds are grown metastabily by a chemical vapor deposition process in which CH4 and H2 are excited by a microwave plasma. Such diamonds are deposited as individual micro-monocrystals or as solid poly crystalline films. The defects in such crystals are related to impurities such as Si and H which produce point defects and tend to nucleate graphite, which can generate planar defects. Nucleation of a diamond phase on β-SiC is also considered, because of the lattice matching between them.Diamond structure is a prototype of a family of related phases such as cubic BN (sphalerite structure) and solid solutions of diamond and cubic BN, Cubic BN-diamond solid solutions (BN)x(C2)1-x,0<x<l are, in turn, a prototype of AIIIBV-CIV phases, of which (GaP)x(Si2)1-x,0<x<l is an example. Substitution of B-N (or Ga-P) by C-C (or Si-Si) atom pairs at lattice sites is characteristic of these solid solutions.