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Los Alamos National LaboratoryCenter for Integrated Nanotechnologies
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2020 Highlights

A selection of CINT science highlights from staff and user research.

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  • Dan Hooks
  • In-Situ Characterization and Nanomechanics Thrust
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  • Nan Li
  • In-Situ Characterization and Nanomechanics Thrust
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Tuning Mechanical Properties of Molecular Crystals

Scientific Achievement

For the first time, scientists have measured and quantified mechanical property changes in molecular materials after introducing engineered defects into uric acid crystals. They found increased softening at low dopant concentrations and increased material strength at high concentrations.

Significance and Impact

The concentrations used in this research simulate the typical impurity levels in commodity chemicals used in industry. The results also point toward a new way to tailor molecular crystal mechanical properties in cases where increased plasticity may be beneficial, such as in pharmaceuticals.

Research Details

Artistic rendering showing that uric acid crystals with doped (i.e., dyed) sectors of increasing concentrations exhibit a trend of softening followed by strengthening.
  • Doped anhydrous uric acid crystals with two different dyes to detect and spectroscopically quantify their incorporation into the crystal lattice.
  • Mechanical testing was performed using nanoindentation measurements across different sectors of the crystals.
  • Crystals with low dye concentrations exhibited ∼50% reduction in stiffness. High concentrations exhibited material strengthening as well as other morphological changes possibly related to reductions in lattice strain.
  • The image is an artistic rendering showing that uric acid crystals with doped (i.e., dyed) sectors of increasing concentrations exhibit a trend of softening followed by strengthening.

Publication: Liu F, Hooks DE, Li N, Rubinson JF, Wacker JN, Swift JA. "Molecular Crystal Mechanical Properties Altered via Dopant Inclusion." Chemistry of Materials. 2020 Apr 23;32(9):3952-9. [DOI: 10.1021/acs.chemmater.0c00433]

Funding: We are grateful for financial support provided by the National Science Foundation (DMR 1609541 and DMR 1306247). J.N.W. is grateful to the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists, Office of Science Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education (ORISE) for the DOE. ORISE is managed by ORAU under contract number DE-SC0014664.This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Los Alamos National Laboratory, an affirmative action equal opportunity employer, is managed by Triad National Security, LLC for the U.S. Department of Energy’s NNSA, under contract 89233218CNA000001. We also thank Stosh Kozimor for microspectrometer access.