These split interstitials are often called dumbbell interstitials .
Plotting the two atoms forming the interstitial with two large spheres and a thick line joining them makes the structure resemble a dumbbell weight - lifting device .
These split interstitials are often called dumbbell interstitials , because plotting the two atoms forming the interstitial with two large spheres and a thick line joining them makes the structure resemble a dumbbell weight - lifting device .