Transmission electron microscopy was used to observe directly dislocation loops which were related to vacancies, and the formation mechanism of dislocation loops was analyzed. It was concluded that the Frank dislocation loops which were found on (111) planes were probably the result of vacancy condensation. During crystal growth at high temperatures, and rapid quenching from high temperatures and high pressures, excess saturated vacancies aggregated into vacancy discs on the (111) close-packed plane. Their subsequent collapse then formed Frank dislocation loops. The average size of the Frank dislocation loops was 30 to 70nm, and their shape was hexagonal. The Burgers vectors of the dislocation loops were normal to the plane of the loops.

Frank Dislocation Loops Related to Vacancies in HPHT As-Grown Synthetic Diamond Single Crystals. L.W.Yin, M.S.Li, J.J.Cui, D.S.Sun, Z.Y.Hao: Scripta Materialia, 2001, 45[1], 13-7