PLASMA DRIVEN SUPERPERMEATION OF HYDROGEN THROUGH GROUP VA METALS

A barrier for the absorption of hydrogen molecules generated by a nonm etallic film on a metal surface may result in superpermeation of supra thermal hydrogen particles. Virtually all the sticking or implanted pa rticles may permeate through the metallic membrane, with a permeation flux depending neither on the metal temperature nor on its thickness. Niobium and vanadium membranes with oxicarbide monolayer films were im mersed in a hydrogen plasma in order to study their interaction with h ydrogen ions in the energy range from a few eV to 250 eV, controlled b y changing the membrane bias. A stable superpermeation flux was observ ed up to ion energies of tens of eV without special efforts to maintai n the surface film. We found that the nonmetal monolayer film remains absolutely stable under the sputtering, including chemical sputtering, by hydrogen particles of energy less than approximate to 50 eV. Thus superpermeability appears to be an intrinsic feature of the investigat ed systems of ''nonmetallic film-metal-hydrogen particles of energy lo wer than 50 eV.'' (C) 1998 American Institute of Physics. [S0021-8979( 98)04517-4].