Real-time sub-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Å</mml:mi></mml:math>ngstrom imaging of reversible and irreversible conformations in rhodium catalysts and graphene

Kisielowski, Christian; Wang, Lin‐Wang; Specht, P.; Calderón, H.A.; Barton, Bastian; Jiang, Bin; Kang, Jun-Koo; Cieslinski, Robert

doi:10.1103/physrevb.88.024305

Cited by 58 publications

(93 citation statements)

References 61 publications

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“…This matches well with the expected value of 143 pm and is consistent with previous reports of measured bond length variations of single-crystal regions of monolayer graphene imaged under similar conditions 13 . The uncertainty in measured bond lengths may be the result of a combination of possible contributing factors, which include lateral drift in the sample stage, a combination of tilting and mechanical vibration, or local phonon excitations to the lattice by the illuminating beam 43 . In the central region of the grain boundary, the bond lengths vary between 115 and 185 pm, with many of the individual bonds having lengths within the range of the single-crystal regions of graphene.…”

Section: Resultsmentioning

confidence: 99%

Measurement of the intrinsic strength of crystalline and polycrystalline graphene

et al. 2013

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The mechanical properties of materials depend strongly on crystal structure and defect configuration. Here we measure the strength of suspended single-crystal and bicrystal graphene membranes prepared by chemical vapour deposition. Membranes of interest are first characterized by transmission electron microscopy and subsequently tested using atomic force microscopy. Single-crystal membranes prepared by chemical vapour deposition show strengths comparable to previous results of single-crystal membranes prepared by mechanical exfoliation. Grain boundaries with large mismatch angles in polycrystalline specimens have higher strengths than their low angle counterparts. Remarkably, these large angle grain boundaries show strength comparable to that of single-crystal graphene. To investigate this enhanced strength, we employ aberration-corrected high-resolution transmission electron microscopy to explicitly map the atomic-scale strain fields in suspended graphene. The high strength is attributed to the presence of low atomic-scale strain in the carbon-carbon bonds at the boundary.

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Section: Resultsmentioning

confidence: 99%

Measurement of the intrinsic strength of crystalline and polycrystalline graphene

et al. 2013

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“…Indeed, as shown in Fig. 2, the interior BTO layers have negligible OOR with a polarization of 32 μC=cm [19]) [20]. the nonpolar CTO layer.…”

Section: Aberration-correctedmentioning

confidence: 78%

When One Plus One is More than Two

Junquera

2016

Physics

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In ABO 3 perovskites, oxygen octahedron rotations are common structural distortions that can promote large ferroelectricity in BiFeO 3 with an R3c structure [1] but suppress ferroelectricity in CaTiO 3 with a Pbnm symmetry [2]. For many CaTiO 3 -like perovskites, the BiFeO 3 structure is a metastable phase. Here, we report the stabilization of the highly polar BiFeO 3 -like phase of CaTiO 3 in a BaTiO 3 =CaTiO 3 superlattice grown on a SrTiO 3 substrate. The stabilization is realized by a reconstruction of oxygen octahedron rotations at the interface from the pattern of nonpolar bulk CaTiO 3 to a different pattern that is characteristic of a BiFeO 3 phase. The reconstruction is interpreted through a combination of amplitude-contrast sub-0.1-nm high-resolution transmission electron microscopy and first-principles theories of the structure, energetics, and polarization of the superlattice and its constituents. We further predict a number of new artificial ferroelectric materials demonstrating that nonpolar perovskites can be turned into ferroelectrics via this interface mechanism. Therefore, a large number of perovskites with the CaTiO 3 structure type, which include many magnetic representatives, are now good candidates as novel highly polar multiferroic materials [3].

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“…A total dose of approximately 850 C/cm [2] was used to acquire the whole image series. This dose is still high compared to what is possible with TEM [11], but for STEM, it is 1% of the dose previously used for sub-picometer precision on single-crystal samples and 19% of the dose used for a few picometer precision on a Pt nanoparticle [8]. The 240 image series was NR-registered [8,9] and averaged to increase image SNR and to remove all sizes of distortions introduced by instabilities of the electron probe and sample during image series acquisition.…”

Section: Methodsmentioning

confidence: 99%

High-precision scanning transmission electron microscopy at coarse pixel sampling for reduced electron dose

Yankovich

Berkels

Dahmen

et al. 2015

Adv Struct Chem Imag

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Determining the precise atomic structure of materials' surfaces, defects, and interfaces is important to help provide the connection between structure and important materials' properties. Modern scanning transmission electron microscopy (STEM) techniques now allow for atomic resolution STEM images to have down to sub-picometer precision in locating positions of atoms, but these high-precision techniques generally require large electron doses, making them less useful for beam-sensitive materials. Here, we show that 1-to 2-pm image precision is possible by non-rigidly registering and averaging a high-angle dark field image series of a 5-to 6-nm Au nanoparticle even though a very coarsely sampled image and decreased exposure time was used to minimize the electron dose. These imaging conditions minimize the damage to the nanoparticle and capture the whole nanoparticle in the same image. The high-precision STEM image reveals bond length contraction around the entire nanoparticle surface, and no bond length variation along a twin boundary that separates the nanoparticle into two grains. Surface atoms at the edges and corners exhibit larger bond length contraction than atoms near the center of surface facets.

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Real-time sub-Ångstrom imaging of reversible and irreversible conformations in rhodium catalysts and graphene

Cited by 58 publications

References 61 publications

Measurement of the intrinsic strength of crystalline and polycrystalline graphene

Measurement of the intrinsic strength of crystalline and polycrystalline graphene

When One Plus One is More than Two

High-precision scanning transmission electron microscopy at coarse pixel sampling for reduced electron dose

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