Strain-induced interaction of hydrogen atoms in hcp rare earth metals

Abstract

The energies of strain-induced (elastic) H–H and D–D interaction are calculated for the hcp rare earth metals Sc, Y, Gd, Tb, Dy, Ho, Er, and Lu taking into account the discrete atomic structure of the host lattice. The elastic constants, lattice spacing of the host lattice, and concentration expansion coefficients of the solid solution lattice due to dissolved atoms are the input numerical parameters used. The interaction is oscillating and is of the long-range nature. In all solid solutions, a significant elastic attraction exists in the first two coordination shells. A comparative analysis of H–H and D–D interaction energies in hcp metals with those in bcc and fcc solid solutions revealed the determining effect of the crystal lattice type on both interaction energy value and its dependence on interatomic distances. The difference between the interaction energies for different rare earth metals is also significant. In general, the strain-induced H–H and D–D interactions in hcp rare earth metals are weaker than in bcc solid solutions and are of the same order as in fcc solid solutions.