Cubic boron nitride crystalline super-abrasive powder (Borazon* CBN 400), consisting of 200-300μm sized amber-coloured crystallites prepared by HP/HT synthesis, was examined from 2.1 to 293K by X-band electron spin resonance spectroscopy. The observed spectrum consisted of a component line A1, visible in the whole temperature range, and 2 component lines A2 and A3, visible at high and low temperatures, respectively. The A1 and A3 lines originate from transitions inside S = 1/2 ground states of distinct paramagnetic species and A2 from transitions inside an excited state of another paramagnetic center. The intensity of the A1 and A3 lines changed differently during in situ low temperature illumination in the UV-VIS range.

ESR Characterization of Point Defects in Amber Coloured c-BN Super Abrasive Powders. S.V.Nistor, D.Ghica, M.Stefan, A.Bouwen, E.Goovaerts: Physica Status Solidi A, 2004, 201[11], 2583-90