Transformation of GR1 defects in annealed natural type IIa diamonds

A sample of the natural type IIa diamond was pre-irradiated in a nuclear reactor and then annealed under isothermal conditions at 550 degrees C. The experimental data were used to calculate a decrease in concentration of the neutral vacancy defect called GR1, corresponding to a phononless band (PLB) at 741 nm, and an increase in concentration of the derivative defect H3 with PLB at 503.2 nm for a broad range of annealing times (0-300 h) and temperatures (100-900 degrees C). Calculations performed using a single activation energy E-m = 2.43 eV for both fast and slow components of the GR1 defect transformation process indicate that the annealing of GR1 and the production of H3 are really observable above 450 degrees C (400 degrees C being the threshold temperature). At 700-900 degrees C, the fast component contributes over the annealing time interval 0.002-0.251 h, after which the annealing of GR1 is determined by the slow component alone. (C) 2000 MAIK Nauka/Interperiodica.