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sp2-to-sp3 transitions in graphite during cold-compression
Xiaohong Yuan1, Yong Cheng2, Hu Tang1,3
1Academy for Advanced Interdisciplinary Studies & Shenzhen Engineering Research Center for Frontier Materials Synthesis at High Pressures, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China. hansb@sustech.edu.cn.
Physical Chemistry Chemical Physics : PCCP
|April 21, 2022
Summary
Researchers discovered a lower pressure (9.7 GPa) for graphite
Area of Science:
- Materials Science
- Condensed Matter Physics
Background:
- Graphite undergoes pressure-induced sp2-to-sp3 transitions.
- Typically, 15-18 GPa is required for these transitions at room temperature.
- High-pressure phases of graphite are generally unquenchable.
Purpose of the Study:
- To investigate the effect of a methanol-ethanol-water mixture as a pressure-transmitting medium on graphite's structural transitions.
- To characterize the resulting sp3-bonded phases in recovered samples.
Main Methods:
- In situ Raman spectroscopy
- X-ray diffraction (XRD)
- X-ray photoelectron spectroscopy (XPS)
- High-resolution transmission electron microscopy (HRTEM)
Main Results:
- The onset pressure for structural transition was reduced to 9.7 GPa using the MEW mixture.
- An additional G_D Raman peak indicated the formation of sp3 bonding.
- Recovered samples showed evidence of sp3 bonds and a unique cross-stacking feature.
Conclusions:
- The methanol-ethanol-water mixture significantly lowers the pressure required for graphite's sp2-to-sp3 transition.
- This study reveals the presence of quenched sp3-bonded phases with unique structures.
- Findings offer insights into compression mechanisms in graphite-like materials.
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