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.
Superconducting phase diagram Updated +Created
There are various possibilities for the axes, but some common ones:
Figure 1.
Sketch of the typical superconducting phase diagram of a Type-I superconductor
. Source.
Figure 2.
Sketch of the typical superconducting phase diagram of a Type-II superconductor
. Source.