Preparation and Characterization of Mesoscale Single Crystals

Elke Arenholz - Chess

"It is expected that such bulk single crystals will enable fundamental understanding and control of emergent mesostructure-based properties in block-copolymer-directed metal, semiconductor, and superconductor materials."

Small-angle X-ray scattering (SAXS) setup and analysis for a nanocomposite polymer.

Small-angle X-ray scattering (SAXS) setup and analysis for a nanocomposite polymer. (a) SAXS patterns were collected as samples moved orthogonally to the beam. Each 2D SAXS pattern forms one pixel of final maps. b) Photo of mounted sample. c) Map of the fraction of identified Bragg reflections accounted for by calculated diffraction patterns. d) Orientation map where colors denote gyroid orientation relative to X-axis in (a) .

What did the Scientists Discover?
Single crystals are materials with periodic structure that extends across macroscopic distances as a coherent lattice free of grain boundaries. By isolating and studying their properties, bulk single crystals have revolutionized our fundamental understanding of materials from semiconductors to biomacromolecules, fueling innovations from microelectronic devices to pharmaceutical compounds. In contrast, our understanding of many mesostructured materials is still in its infancy in part due to the lack of available single crystals. Block copolymer self-assembly of mesostructured systems presented here is a promising method to prepare periodic 10–100 nm structures with coherent orientation over macroscopic lengths enabling their study.

Why is this important?
The method presented here can prepare macroscopic bulk single crystals with other block copolymer systems, suggesting that the method is broadly applicable to block copolymer materials assembled by solvent evaporation. It is expected that such bulk single crystals will enable fundamental understanding and control of emergent mesostructure-based properties in block-copolymer-directed metal, semiconductor, and superconductor materials.

Representative SAXS patterns with log scale colors
Representative SAXS patterns with log scale colors from locations as indicated in (c), exhibiting polycrystalline (e), multi-(three) crystalline (f), and single crystal (g) behavior. Diagonal bars across bottom are shadows from photodiode wire.

Why did this research need CHESS?
Small-angle X-ray scattering (SAXS) at CHESS was used to characterize mesostructure by spatially mapping 2 cm2 of each sample with a 100 µm × 100 µm collimated beam in steps of 100 µm along directions orthogonal to the beam. An algorithm extracted gyroid crystal orientation for tens of thousands of SAXS patterns by comparing measured Bragg reflection positions with calculated diffraction patterns crucial to fully characterize the structure of the material.

Collaborators:

  • Ethan M. Susca, Department of Materials Science and Engineering, Cornell University
  • Peter A. Beaucage, Department of Materials Science and Engineering, Cornell University
  • R. Paxton Thedford, Department of Materials Science and Engineering, Cornell University
  • Andrej Singer, Department of Materials Science and Engineering, Cornell University
  • Sol M. Gruner, Department of Materials Science and Engineering, Cornell University
  • Lara A. Estroff , Department of Materials Science and Engineering, Cornell University
  • Ulrich Wiesner, Department of Materials Science and Engineering, Cornell University

Publication Citation:
Susca, E. M., Beaucage, P. A., Thedford, R. P., Singer, A., Gruner, S. M., Estroff, L. A., Wiesner, U., “Preparation and Characterization of Mesoscale Single Crystals,” Adv. Mater., 2019, 31, 1902565 https://doi.org/10.1002/adma.201902565

How was the work funded?
X-ray experiment at CHESS were supported by NSF award DMR-1332208 and neutron scattering at the NIST Center for Neutron Research is supported through a partnership between NIST and NSF under agreement DMR-1508249.