miscibility gap

https://doi.org/10.1351/goldbook.MT07270
Area within the coexistence curve of an isobaric phase diagram (temperature vs composition) or an isothermal phase diagram (pressure vs composition).
Note:
A @MT07230@ gap is observed at temperatures below an @UT07280@ (UCST) or above the lower @C01401@ (LCST). Its location depends on pressure. In the @MT07230@ gap, there are at least two phases coexisting.
Source:
PAC, 2004, 76, 1985. (Definition of terms related to polymer blends, composites, and multiphase polymeric materials (IUPAC Recommendations 2004)) on page 1996 [Terms] [Paper]