# Dumbbells

| A more symmetrical position for an interstitial atom may be obtained if two atoms share the space of one.
|  | This is illustrated below for a fcc crystal; a configuration like this is called a dumbbell. In the dumbbell configuration, the interstitial now has a preferred direction; it is no longer isotropic.
| In bcc crystals, a dumbbell configuration exists, too; it is shown below. Again, the interstitial now has a preferred direction.

With frame

1.3.3 The larger View and Complications

2.1.2 Frenkel Defects

3.3.1 Determination of Diffusion Profiles

© H. Föll (Defects - Script)