The Microstructure of Pharmaceutical Materials Revealed by Scanning Electron Diffraction

Abstract

The microstructure of pharmaceutical materials influences important physical properties [1] such as compaction behavior, dissolution rate, bioavailability, hygroscopicity, dehydration, chemical stability and physical stability. However, few techniques are capable of directly revealing the underlying microstructure and associated defects. Transmission electron microscopy (TEM) provides an obvious means to image and characterize microstructure and defects. Whilst previous TEM studies of pharmaceutical materials have been insightful [2] the level of detail attained has been necessarily limited because of the sensitivity of the sample to damage by electron irradiation. Scanning electron diffraction (SED) provides a new paradigm in which the data required for detailed analysis is acquired rapidly and before the specimen is destroyed. Insight is gleaned post-facto through the application of versatile computational analysis enabling maximal information to be extracted from the data.