Ion beam analysis of deuterium-implanted Al2O3 and tungsten

Single crystal tungsten and Al2O3 (sapphire), and polycrystalline WESGO-995 Al2O3 samples were implanted with 20-30 keV deuterium at 300-500 K. The de uterium distributions were determined using He-3-D nuclear reaction analysi s, at 300-800 K. The results indicated that considerable diffusion occurred both during the implantations and during the subsequent analysis. Modellin g the data indicates effective (radiation-enhanced) diffusivities as high a s 10(-16) m(2)/s in Al2O3, compared to a thermal diffusivity similar to 10( -41) m(2)/s at 300 K [J.D. Fowler, D. Chandra, T.S. Elliman, A.W. Payne, K. Verghese, J. Am. Ceram. Soc. 60 (1977) 155.]. The modelling also suggests that most of the implanted deuterium was released at the surface, although a significant fraction diffuses to depths greater than the expected ion ran ge. In tungsten, implanted deuterium is trapped at defects that appear to b e mobile at 300 K, enabling the deuterium distribution to extend much deepe r than the ion range. At higher temperatures the trap energy appears to inc rease with time. Modelling the data indicates little deuterium release thro ugh the front surface, i.e. most diffused deeper into the bulk of the sampl e. (C) 1998 Elsevier Science B.V. All rights reserved.