Prismatic dislocation loops and concentric dislocation loops in HPHT-grown diamond single crystals

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2003-02, Vol.343 (1), p.158-162
• Main Authors: Yin, Long-Wei, Li, Mu-Sen, Zou, Zeng-Da, Gong, Zhi-Guang, Hao, Zhao-Yin
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.); Dislocation loops; Exact sciences and technology; Inclusions; Physics; Structure of solids and liquids; crystallography; Transmission electron microscopy; Vacancies
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/S0921-5093(02)00385-4

As-grown diamond single crystals grown from Fe–Ni–C system under high temperature–high pressure were examined by transmission electron microscopy. There exist prismatic dislocation loops and concentric dislocation loops in the diamond, which are related to the nonequilibrium nature of the diamond synthesis process. The prismatic dislocation loops may be formed by vacancy condensation during rapid cooling from high temperature, and the Burgers vector of the dislocation is determined by diffraction contrast as 1/2〈1 1 0〉. Moiré fringes formed by two overlapping (1 1 1) close-packed planes were used to study concentric dislocation loops. The concentric dislocation loops may be derived from thermal stress caused by the inclusions in the diamond, which cause a strain field due to the thermal contraction difference between the inclusions and the diamond during cooling from high temperature.