Percent Crystallinity

Many materials, especially polymers, tend to form both crystalline and non-crystalline forms. Each structure produces a unique diffraction pattern that enables us to determine the relative amounts of each phase. Amorphous (”glassy”) phases produce one or more broad humps in the diffraction pattern, while crystalline materials produce a series of sharper peaks superimposed on the amorphous humps.

One way to determine the relative amounts of amorphous and crystalline phases is to spike the material with a known crystalline phase. Then, with the aid of a Rietveld refinement, all of the other crystalline phases can be calibrated against the known amount of the spiking agent. The amorphous content is then determined by difference (100% – sum of all the crystalline phases). In order to perform this analysis, however, one must know a great deal about all of the crystalline phases. If this information is not known, then an alternative method can be used that estimates the percent crystallinity based on the relative areas of the amorphous and crystalline regions.

Applications include:

  • Studies of polymers & pharmaceuticals
  • Conversion of pharmaceutical polymorphs
  • Glass content in ceramics
  • Analysis of clays & minerals
  • Rapidly solidified metallic glasses
  • Analysis of ashed samples
  • Devitrification of glass