Allotrope Updated +Created
Single chemical element, single phase (usually solid), but different 3D structures.
The prototypical examples are the allotropes of carbon such as diamond vs graphite.
Chicago Pile-1 Updated +Created
Video 1.
Getting funding for the Chicago Pile Edward Teller interview by Web of Stories (1996)
Source.
Video 2.
German graphite from The Genius Behind the Bomb (1992)
Source. Graphite was expensive because it had to be boron-free, since boron absorbs neutrons. But a boron process was the main way to make graphite. This type of pure graphite is known as nuclear graphite.
Fullerene Updated +Created
Video 1.
Buckyballs (C60) by Periodic Videos (2010)
Source. Actually shows them in a lab!
Graphene Updated +Created
A single layer of graphite.