Huang et al. from Cornall University produced some astonishing images of graphene grains that resembled a patchwork quilt. These images have been published in Nature.
How Were These Images Obtained and What Do They Tell Us?
To obtain these images the researchers used TEM and diffraction-filtered imaging to show the location, orientation and boundaries of hundreds of graphene grains. Their findings confirmed that grain boundaries weaken the mechanical strength of graphene, but have no significant effect the electrical properties.
Composite Dark-Field TEM Images of Graphene Grains
Below you will see a false-color, composite dark-field TEM image of graphene grains. In this image, each color represents graphene of a different crystallographic orientation. These images were acquired through 10 nm Silicon Nitride windows and were taken by Pinshane Huang at Cornell University.
Huang's original work was performed with microporous TEM films where post-imaging background substraction was performed. Current work and future studies are being conducted at Cornell using TEMwindows' robust and ultrathin 10 nm silicon nitride, which provides an excellent background-free imaging substate.
Bright patches indicate graphene grains of a ~10 range of crystallographic orientations. On the left, getting a complete picture of the graphene grain structure is difficult because the thick membrane obstructs much of the lattice. Moving to thin windows (on the right), we can get comparable contrast while viewing larger continuous areas. The particles on the right image are from a dirty graphene sample, not the grid. Scale bars are 2 microns.
Substrates for High-Resolution Imaging
TEMwindows.com recommend the following TEM Window grids for high-resolution imaging of nanoparticles or nanotubes:
- 5 nm thick UltraSM® Pure Silicon TEM Windows are the thinnest imaging, plasma cleanable substrate we offer and have less chromatic blur than ultrathin carbon.
- NANOPOROUS UltraSM® Pure Silicon TEMwindows have 10-60 nm diameter nanopores on which nanoscale materials may be suspended for truly background-free imaging
- 10 nm Silicon Nitride TEM windows are perfectly flat and robust enough for most sample preparation procedures
This information has been sourced, reviewed and adapted from materials provided by SiMPore Inc.
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