Effect of paired states in the electronic spectrum of transition metals on hydrogen absorption

Abstract

Hydrogen absorption by transition metals is analyzed in terms of crystal-field theory. A proton occupying interstitial sites in the crystal lattice of a metallic absorbent is assumed to split fivefold degenerate d-orbitals of the metal. The proposed scheme of the filling of these orbitals accounts for the good absorption properties of the d 1–d 5 metals, the hydrogen absorption behavior of chromium and manganese, and the change in the thermodynamic parameters of the absorption process after the appearance of paired electrons in the electronic spectrum of the metals. We consider the influence of zero-point vibrations of hydrogen atoms incorporated into interstices of the crystal lattice of metals on some aspects of hydrogen absorption.