XRD Evaluation of Relative Mechanical Strength and Irradiation Resistance of Synthetic Diamond

Abstract

We continue here our previous work where SD powders were significantly strengthened by irradiation with electrons of lower energy under smaller dose. Previous results were obtained from the crushing strength analysis, no XRD was applied. In present work, powders of synthetic diamond with low strengthwere sorted on sets with different grain size. As established, the sets had various crushing strengths and morphology. They were irradiated with high energy electrons (6.5 MeV, D = 2 × 10 19 and D = 6 × 10 19 cm ?2 , Tirr = 450 K) and analyzed using XRD (CuKα) before and after irradiation. Nonlinear dependences a(Θ) = f{R(Θ), where a(Θ) is lattice constant and R(Θ) is Raily function, and the discovered extra-splits (additional to α1-α2-doublets on CuKα) of basic peaks in XRD patterns from the SD sets, testified that crystal lattice of diamond in sets was variously distorted, like of cBN doped with rare earth elements. As established, the first irradiation led to decreasing distortions, the more significantly the higher initial strength of the set. The second irradiation produced softening and increasing distortions of crystal lattice of diamond, the more effectively the less initial strength of diamond. XRD allows indirectly to presort synthetic diamond off the material with critically low relative mechanical strength as well as evaluate resistance of diamond crystal lattice against heavy irradiation and other external impacts.