Dislocation behaviors in nanotwinned diamond

Xiao, Jianwei; Yang, He; Wu, Xiaozhi; Younus, Fatima; Li, Peng; Wen, Bin; Zhang, Xiangyi; Wang, Yanbin; Tian, Yongjun

doi:10.1126/sciadv.aat8195

Cited by 44 publications

(25 citation statements)

References 38 publications

(63 reference statements)

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“…The dislocations in {111} slip planes of diamond have been theoretically investigated in early study 33,34 , showing the shuffle-set and glide-set. Here, we further investigate the atomic mechanism of the {100}<110> slip process by density functional theory based molecular dynamics simulations.…”

Section: Resultsmentioning

confidence: 99%

Direct Observation of Room-Temperature Dislocation Plasticity in Diamond

Nie

Huang

et al. 2020

Matter

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It is well known that diamond does not deform plastically at room temperature and usually fails in catastrophic brittle fracture. Here we demonstrate room-temperature dislocation plasticity in sub-micrometer sized diamond pillars by in-situ mechanical testing in the transmission electron microscope. We document in unprecedented details of spatio-temporal features of the dislocations introduced by the confinement-free compression, including dislocation generation and propagation. Atom-resolved observations with tomographic reconstructions show unequivocally that mixedtype dislocations with Burgers vectors of 1/2<110> are activated in the non-close-packed {001} planes of diamond under uniaxial compression of <111> and <110> directions, respectively, while being activated in the {111} planes under the <100> directional loading, indicating orientationdependent dislocation plasticity. These results provide new insights into the mechanical behavior of diamond and stimulate reconsideration of the basic deformation mechanism in diamond as well as in other brittle covalent crystals at low temperatures. 2

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Section: Resultsmentioning

confidence: 99%

Direct Observation of Room-Temperature Dislocation Plasticity in Diamond

Nie

Huang

et al. 2020

Matter

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“…The maximum attainable local tensile strain of 9.6% on the tensile side of <110> single-crystal natural diamond samples (2), as compared to theoretical predictions of higher values (SI Appendix, Fig. S4 and Table S1), could be attributed to the presence of dislocations and/or other surface-related defects (14)(15)(16)(17). The compressive side is more tolerant to deformation.…”

Section: Significancementioning

confidence: 79%

Metallization of diamond

Shi

Dao

Tsymbalov

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Experimental discovery of ultralarge elastic deformation in nanoscale diamond and machine learning of its electronic and phonon structures have created opportunities to address new scientific questions. Can diamond, with an ultrawide bandgap of 5.6 eV, be completely metallized, solely under mechanical strain without phonon instability, so that its electronic bandgap fully vanishes? Through first-principles calculations, finite-element simulations validated by experiments, and neural network learning, we show here that metallization/demetallization as well as indirect-to-direct bandgap transitions can be achieved reversibly in diamond below threshold strain levels for phonon instability. We identify the pathway to metallization within six-dimensional strain space for different sample geometries. We also explore phonon-instability conditions that promote phase transition to graphite. These findings offer opportunities for tailoring properties of diamond via strain engineering for electronic, photonic, and quantum applications.

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“…For diamond, dominant dislocations are along the <110> directions slipping in the (111) plane with Burgers vector of 1 2 <110> for perfect dislocation and 1 6 <112> for glide-set partial dislocation 14,18 . According to the angle between Burgers vector and dislocation line direction, there are six types of dislocations: glide-set 0°perfect dislocations, glide-set 30°partial dislocations, glide-set 60°perfect dislocations, glide-set 90°partial dislocations, shuffle-set 0°perfect dislocations, and shuffle-set 60°perfect dislocations 14 . Among them, shuffle-set 0°perfect dislocation has the lowest critical resolved shear stress (CRSS) for dislocation motion and the lowest barrier strength when reacting with TBs 14 .…”

Section: Dislocation Slip Modes In Int-diamond Grainsmentioning

confidence: 99%

“…According to the angle between Burgers vector and dislocation line direction, there are six types of dislocations: glide-set 0°perfect dislocations, glide-set 30°partial dislocations, glide-set 60°perfect dislocations, glide-set 90°partial dislocations, shuffle-set 0°perfect dislocations, and shuffle-set 60°perfect dislocations 14 . Among them, shuffle-set 0°perfect dislocation has the lowest critical resolved shear stress (CRSS) for dislocation motion and the lowest barrier strength when reacting with TBs 14 . Here the CRSS is defined as the threshold stress of dislocation motion, and the barrier strength is defined as the threshold stress of dislocation reaction with the TB when the activation energy reaches zero 19 .…”

Section: Dislocation Slip Modes In Int-diamond Grainsmentioning

confidence: 99%

“…The recent molecular dynamic (MD) simulations on nt-diamond indicated that the origin of the unprecedented hardness originates from two factors: high lattice frictional stress due to the strong sp 3 C-C bonding and high athermal stress due to Hall-Petch effect 14 . Experimental and theoretical studies also show that twin boundaries (TBs) can continuously harden covalent materials with decreasing twin thickness (λ) to very small values (on the order of a few nm) 7,8,15,16 .…”

Section: Introductionmentioning

confidence: 99%

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Intersectional nanotwinned diamond-the hardest polycrystalline diamond by design

Xiao

Wen

et al. 2020

npj Comput Mater

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The hardness of nanotwinned diamond (nt-diamond) is reported to be more than twice that of the natural diamond, thanks to the fine spaces between twin boundaries (TBs), which block dislocation propagation during deformation. In this work, we explore the effects of additional TBs in nt-diamond using molecular dynamics (MD) calculations and introduce a novel intersectional nanotwinned diamond (int-diamond) template for future laboratory synthesis. The hardness of this int-diamond is predicted by first analyzing individual dislocation slip modes in twinned grains and then calculating the bulk properties based on the Sachs model. Here we show that the hardness of the int-diamond is much higher than that of nt-diamond. The hardening mechanism of intdiamond is attributed to the increased critical resolved shear stress due to the presence of intersectional TBs in nt-diamond; this result is further verified by MD simulations. This work provides a new strategy for designing new super-hard materials in experiments.

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Dislocation behaviors in nanotwinned diamond

Abstract: The unprecedented hardness of nt-diamond originates from high lattice frictional stress and high athermal stress.

Cited by 44 publications

References 38 publications

Direct Observation of Room-Temperature Dislocation Plasticity in Diamond

Direct Observation of Room-Temperature Dislocation Plasticity in Diamond

Metallization of diamond

Intersectional nanotwinned diamond-the hardest polycrystalline diamond by design

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