From NSDL Materials Digital Library Wiki
Structural phase diagrams are widely constructed as a means to summarize a wide range of structural behaviors. The simplest example of a structural phase diagram is for hard spheres, where structural behavior is a function of volume fraction only. Typically structural phase diagrams are plotted as a function of two dimensions. For example, in the study of Block Copolymer melts, structure is usually plotted as a function of temperature (or the Flory-Huggins Chi Parameter) and block fraction. Surfactant structural behavior is often plotted as a function of temperature and volume fraction (concentration).
-  Matsen MW, Bates FS, Unifying weak- and strong-segregation block copolymer theories, MACROMOLECULES 29 (4): 1091-1098 FEB 12 1996