Content deleted Content added
m spelling correction |
m I added a link to the "Phase diagram" page |
||
Line 95:
== Phase diagram ==
This type of phase transformation is known as '''spinodal decomposition''', and can be illustrated on a [[phase diagram|Phase diagram]] exhibiting a miscibility gap. Thus, phase separation occurs whenever a material transition into the unstable region of the phase diagram. The boundary of the unstable region sometimes referred to as the binodal or coexistence curve, is found by performing a common tangent construction of the free-energy diagram. Inside the binodal is a region called the spinodal, which is found by determining where the curvature of the free-energy curve is negative. The binodal and spinodal meet at the critical point. It is when a material is moved into the spinodal region of the phase diagram that [[spinodal decomposition]] can occur.<ref name=Jones>{{Cite book|last = Jones|first = Richard A. L.|title = Soft Condensed Matter|url = https://books.google.com/books?id=Hl_HBPUvoNsC|access-date = 2007-10-22|publisher = Oxford University Press|isbn = 978-0-19-850589-1|pages = 33|year = 2004|orig-year = 2002}}</ref>
The [https://www.doitpoms.ac.uk/tlplib/phase-diagrams/freeenergy.php#:~:text=The%20phase%20with%20the%20lowest,the%20liquid%20phase%20is%20stable. free energy curve] is plotted as a function of composition for a temperature below the convolute temperature, T. Equilibrium phase compositions are those corresponding to the free energy minima. Regions of negative curvature (∂<sup>2</sup>f/∂c<sup>2</sup> < 0 ) lie within the inflection points of the curve (∂<sup>2</sup>f/∂c<sup>2</sup> = 0 ) which are called the spinodes. Their locus as a function of temperature defines the spinodal curve. For compositions within the spinodal, a homogeneous solution is unstable against infinitesimal fluctuations in density or composition, and there is no thermodynamic barrier to the growth of a new phase. Thus, the spinodal represents the limit of physical and chemical stability.
| |||