STABILIZATION OF THE HEXAGONAL CLOSE-PACKED PHASE OF COBALT AT HIGH-TEMPERATURE

The structure of thin cobalt films sputtered on a rhenium buffer was a nalyzed from room temperature to 963 K, using the perturbed angular co rrelation technique with the In-111/Cd-111 probe. The hyperfine field corresponding to the fee phase, which is the stable one above 704 K, i s never observed, and the measured hyperfine field follows closely a t heoretical prediction for the hcp phase. This is a consequence of the good match between the cobalt and the Re hcp lattices that leads to th e stabilization of the hcp phase up to 963 K.