Hydrogen Interaction with Vacancies in Electron Irradiated Niobium

Abstract

Defect studies of Nb irradiated with 10 MeV electrons were performed in the present work by means of positron annihilation spectroscopy. The lattice defects were characterized by positron lifetime spectroscopy. Moreover, defect depth profiles were studied by slow positron implantation spectroscopy. The experimental investigations were accompanied by first principles theoretical calculations of positron parameters. It was found that irradiationinduced vacancies in Nb specimens are surrounded by H, which causes a shortening of the lifetime of trapped positrons. The influence of a Pd and Cr over-layer on the H concentration in the Nb specimens was examined.

Positron Annihilation Studies of the Near-Surface Regions of Niobium before and after Wear Treatment

“…This is a larger value in comparison to other metals, for instance in Cu it is equal to 121(7) nm [13] and in stainless steel 73.7(1.7) nm [27]. Nevertheless, this value coincides with data from the literature, Č ížek et al reported even higher value, i.e., about 319(8) nm [17]. For the sample exposed to dry sliding with the load of 50 N the determined values are equal to: S int = 0.493(1), S surf = 0.515 (1), and the positron diffusion length: L ?…”

“…In fact, in the positron lifetime spectrum measured for virgin samples, only one lifetime component equal to 129(1) ps was resolved. This value coincidences with the value reported in the literature, i.e., 128.3(3) ps for positron annihilation in bulk [16,17].…”

Hydrogen in V-Fe thin films and Fe/V-Fe multi-layered thin films

“…Typical sputtering parameters are summarized in Table 3.1. Two different orientations of sapphire substrate, (0001) and (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) supplied by Crystec GmbH were used to investigate probability of different growth orientation. Some specified conditions will be described on each result.…”

“…In Fig. 3.3 a simulated example of XRR curve of a V 100-nm thick film on a Al2O3 (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) substrate capped by Pd 20-nm thick film is shown. The simulation was done by IMD developed by Windt [Windt98].…”

“…To avoid this, use of heavier isotopes like D instead of H is thus strongly recommended for APT. (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) In air…”