Measurement of process-dependent material properties of pharmaceutical solids by nanoindentation

Xiangmin Liao, Timothy S Wiedmann

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


The purpose of this work was to evaluate nanoindentation as a means to characterize the material properties of pharmaceutical solids. X-ray diffraction of potassium chloride and acetaminophen showed that samples prepared by cooling a melt to a crystalline sample as opposed to slow recrystallization had the same crystal structure. With analysis of the force-displacement curves, the KCl quenched samples had a hardness that was 10 times higher than the recrystallized KCl, while acetaminophen quenched samples were 25% harder than the recrystallized samples. The elastic moduli of the quenched samples were also much greater than that observed for the recrystallized samples. Although the elasticity was independent of load, the hardness increased with load for acetaminophen. With each sample, the flow at constant load increased with applied load. Etching patterns obtained by atomic force microscopy showed that the KCl quenched sample had a higher dislocation density than the recrystallized sample, although there was no evident difference in the acetaminophen samples. Overall, the differences in the observed sample properties may be related to the dislocation density. Thus, nanoindentation has been shown to be a sensitive method for determining a processed-induced change in the hardness, creep, and elasticity of KCl and acetaminophen.

Original languageEnglish (US)
Pages (from-to)79-92
Number of pages14
JournalJournal of Pharmaceutical Sciences
Issue number1
StatePublished - Jan 2005


  • Acetaminophen
  • Creep
  • Elastic modulus
  • Hardness
  • Nanoindentation
  • Potassium chloride
  • Scanning probe microscopy

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