Variations in the surface concentration of N in an ion-doped (100)-oriented monocrystalline foil were studied by using Auger electron spectroscopic and secondary-ion mass spectrometric techniques. The samples were implanted with 50 or 100keV N ions to a dose of 5 x 1017/cm2, and were annealed at 800 to 900C. The diffusivity of N, as estimated from the time of appearance of a maximum N concentration at the sample surface, was 7 to 9 orders of magnitude lower than the value for a solid solution of N in Mo. However, this estimate was 3 to 5 orders of magnitude higher than the self-diffusivity of Mo. It was suggested that a supersaturated solid solution of N formed in the ion-implanted material; where excess N (above the solubility limit) was deposited in radiation defects and migrated, with these defects, during annealing.

Nitrogen Diffusion in a Subsurface Region of Ion-Implanted Molybdenum. E.Y.Zamalin, O.B.Bodnar: Technical Physics Letters, 2001, 27[6], 495-7