Interplay of edge/screw dislocations and enhanced magnetism in exfoliated pyrolytic graphite with distorted hexagonal moiré superlattices

Boi, Filippo S.; Wang, Shanling; Li, Wenxue; Odunmbaku, Omololu; Gao, Shuai; Guo, Jian; Song, Jiaxin; Wen, Jiqiu; Zhang, Hong

doi:10.1016/j.cartre.2021.100106

Cited by 10 publications

(2 citation statements)

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“…These magnetic states have led to the field of twistronics where 2D layered materials can form useful devices by controlling the twist of their layers. Recently, Moiré pattern with these magnetic properties have been seen in highly oriented pyrolytic graphite (HOPG) 22 . Control of screw defects within carbonaceous materials could potentially enable control of the twist angle and be used for twistronic applications.…”

Section: Main Textmentioning

confidence: 97%

“…Screw dislocations could also explain the twisting disorder seen in graphite and magnetic states. Moiré patterns have been observed using scanning tunnelling microscopy and electron microscopy these features are caused by layers being twisted relative to each other 21,22 . Firstly, screws could pin these twisted layers inhibiting the rotation to ideal AB stacking.…”

Section: Main Textmentioning

confidence: 99%

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Graphite forms via annihilation of screw dislocations

Martin¹,

Fogg²,

J.³

et al. 2022

Preprint

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Graphite is the thermodynamically stable form of carbon, and yet is remarkably difficult to synthesise. A key step in graphite formation is the removal of defects at high temperature (>2300 • C) that allow graphenic fragments to rearrange into ordered crystallites 1 . We find the critical defect controlling graphitisation is a screw dislocation that winds through the layers like a spiral staircase, inhibiting lateral growth of the graphenic crystallites (L a ) and preventing AB stacking of Bernal graphite. High-resolution transmission electron microscopy (HRTEM) identifies screws as interdigitated fringes with narrow focal depth in graphitising polyvinyl chloride (PVC). Molecular dynamics simulations of parallel graphenic fragments confirm that screws spontaneously form during heating, with higher annealing temperature driving screw annihilation and crystallite growth. The time evolution of graphitisation is tracked via X-ray diffraction (XRD), showing the growth of L a and reduction of the interlayer spacing consistent with molecular dynamics of screw annihilation. This mechanistic insight raises opportunities to lower the barrier for graphitisation as well as broadening the range of carbonaceous materials that can turn into graphite, thereby lowering the cost of synthetic graphite used in lithium-ion batteries, carbon fibre, and electrodes for smelting.

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Section: Main Textmentioning

confidence: 97%

Section: Main Textmentioning

confidence: 99%