Beryllium’s monocrystal and polycrystal elastic constants

Using resonant-ultrasound spectroscopy, we measured beryllium’s elastic constants for both a monocrystal and a polycrystal. Thus, we consider the monocrystal–polycrystal elastic-constant relationship for hexagonal symmetry. Beside the Cij, we report the Debye characteristic temperature Θ and the Grüneisen parameter γ. We comment on beryllium’s chemical bonding and its remarkably low Poisson ratio.