X-ray analysis of stacking faults in ytterbium

At room temperature ( z 300 K), ytterbium has a predominantly f c c structure [l, 21. However, a small13; amount of the h c p structure corresponding to the low- as well as the high-temperature phases [3-61 is also known to coexist [7, 81 with the room-temperature f c c structure. We have earlier reported [8] that mechanical deformation of 99.2% pure ytterbium specimens at room temperature, induces a partial structural transformation of the type f c c -+ h c p, leading to an enhancement of the h c p component in the deformed material. I t has also been found [9] that surfaces of ytterbium specimens subjected to polishing with emery or to filing also exhibit similar enhancement of the h c p component. These observations suggest that in 99.2% pure ytterbium, the f c c -+ h c p transformation which readily accompanies different types of13; mechanical treatments, is probably associated with the stacking faults in the material.