Nuclear microprobe analysis of Li-7 profile induced in HfB2 by a neutron irradiation

HfB2, a solid poor in boron, was irradiated by thermal neutrons in an exper imental reactor. Using a nuclear microprobe, we have tracked lithium atoms produced by the B-10(n, alpha)Li-7 reaction and compared the calculated and measured Li-7 profiles in HfB2 irradiated samples. This comparison shows t hat Li atoms do not diffuse during irradiation (323 K). The comparison of n on-annealed and annealed irradiated HfB2 plates clearly shows that lithium atoms do not migrate out of samples even at high temperatures (1273 K). The se results associated to previous transmission electron microscopy (TEM) ob servations seem to show that lithium atoms are trapped by dislocation loops created by displacement cascades during neutron irradiation. (C) 2001 Else vier Science B.V. All rights reserved.