On the Definition of Phase Diagram

A phase diagram, which is understood as a graphical representation of the physical states materials under varied temperature and pressure conditions, one basic concepts employed in high-pressure research. Its general definition refers to equilibrium state stability limits particular phases, set stage for its terms use. In literature, however, diagram often appears an umbrella category any pressure–temperature chart that presents not only but also metastable states. The current situation confusing may lead severe misunderstandings. This opinion paper reviews use “phase diagram” term many aspects scientific research suggests some further clarifications. Moreover, this article can serve starting point discussion on refined required view paradigm shift driven by recent results obtained using emerging experimental techniques.