Positron annihilation study of hydrogen trapping at open-volume defects: Comparison of nanocrystalline and epitaxial Nb thin films

Identification of Zn-vacancy–hydrogen complexes in ZnO single crystals: A challenge to positron annihilation spectroscopy

“…In particular, a substantially enhanced H solubility was found in nanocrystalline metals containing a significant volume fraction of grain interfaces which can accumulate more H than a regular lattice, e.g., Pd. 70 Recent defect studies of thin films 71,72 revealed that sputtering at room temperature produces such nanocrystalline structure with a high density of open-volume defects. It was also demonstrated that the H solubility in nanocrystalline films is substantially enhanced.…”

Hydrogen-induced microstructural changes of Pd films

“…Thus, the hydrogen solubility in the a-phase in the nanocrystalline Pd film is roughly eight times higher than in a conventional bulk Pd polycrystal [28]. This effect, which was observed also in other nanocrystalline films [6,9,29], is due to the nanocrystalline structure of the Pd film, which contains a significant volume fraction of grain interfaces, able to accumulate more hydrogen than grain interiors. Moreover, high internal stresses in thin films may influence hydrogen solubility in the a-phase as well [6].…”

“…10b shows a dependence of the S-parameter S Pd and the mean positron diffusion length L þ,Pd for a nanocrystalline Pd layer obtained from fitting of the S(E ) curves on the hydrogen concentration x H . Vacancy-like defects at grain boundaries between nanocrystalline grains act as trapping sites for hydrogen atoms [9]. At low concentrations (x H 0.01), hydrogen preferentially fills the open-volume defects at grain interfaces.…”

“…Hence, the behaviour of hydrogen-loaded thin films fixed on substrates is quite different from that of corresponding bulk samples [6,7] since thin films are strongly influenced by stress imposed to the virgin film by its adhesion to a substrate, hydrogen-induced bi-axial stresses, and the film microstructure itself [1,8,9]. Understanding and prediction of hydrogen behaviour in thin films and hydrogen-induced buckling is highly important since this process may cause catastrophic adhesion failure in many thin film systems or coatings exposed to hydrogen.…”

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

“…4.1). For (110)-oriented film, an estimation of this in-plane compressive stress along[1][2][3][4][5][6][7][8][9][10] is accessible through the modification of Eq. (2.31) as follows.…”