Low temperature relaxations associated with quantum tunnelling of H in Sc and Y

Acoustic spectroscopy and electrical resistivity measurements have been emp loyed to investigate the two relaxation processes occurring at liquid He te mperature in very dilute Y-H and Sc-H alloys, and ascribed to H tunnelling systems near single or paired O traps. Pit very Low H concentration, the pe ak dire to the O-H tunnelling system becomes extremely narrow and is descri bable in terms of incoherent tunnelling with phonon assisted transitions. ( C) 2000 Elsevier Science S.A. All rights reserved.