Thermally induced dislocation movements are crucial in comprehending the results of high-temperature annealing on modifying the crystal structure. In this investigation, defect behavior in suspended monolayer graphene was analyzed at raised temperatures (up to 800 ºC) in situ utilizing TEM.
The authors reported greater movement of the dislocations at high temperatures, which verifies the effect of thermal energy on the system.
- Produce a total atomic structure model of graphene
- Driving force: Property modification of graphene by defects
- Gain knowledge on the dynamics for migration of isolated dislocations in carbon nanomaterials
- Sputtering of bond rotations and carbon atoms
- Electron irradiation may damage the graphene specimen
- The stability of the sample at greater temperatures decreases TEM resolution
Figure 1. HRTEM images of the long-distance glide steps of a dislocation and (a, b) at 500 ºC with a time interval of 17 seconds (jump distance is 2.9 nm); (c – f) at 800 ºC, where the time interval is 62 and 12 seconds (jump distance is 4.0 and 3.6 nm, respectively). The scale bar in panel (a) is 1 nm.
This article outlines the in situ investigation of the temperature-induced motion of dislocation in graphene during heating. The dynamics of dislocation cores was observed at heightened temperatures at the atomic scale for the first time.
The Wildfire S3 system from DENSsolutions provides the total performance of the TEM and resolves the dislocation core and graphene lattice even at 800 ºC.
Operating at an increasing voltage of 80 kV extensively decreased any electron beam damage of the graphene specimen. Maintaining a higher temperature effectively protected against amorphous contamination. This resulted in a higher quality of TEM images.
The motion of the dislocation was seen to increase at higher temperatures and verified the effect of thermal energy on the system.
An evaluation of the dislocation movement demonstrates both glide and climb processes, including large nanoscale rapid jumps between fixed locations in the lattice and new complex pathways for migration.
A significant jump of dislocation (over 2.9 nm) was observed at 500 ºC (Figure 1 (a, b)), which is not a singular event, as two further examples of a long-distance glide at 800 ºC are portrayed in Figure 1 (c – d).
Insights into annealing processes in graphene and the behavior of defects with increased heat are a result of an improved understanding of the high-temperature dislocation movement.
References and Further Reading
- Gong, C., et al. (2015). “Thermally Induced Dynamics of Dislocations in Graphene at Atomic Resolution.” ACS nano 9(10): 10066-10075.
- Wu, Y. A., et al. (2012). “Large Single Crystals of Graphene on Melted Copper Using Chemical Vapor Deposition.” ACS nano 6(6): 5010-5017.
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