Quantitative atomic resolution mapping using high-angle annular dark field scanning transmission electron microscopy

Aert, Sandra Van; Verbeeck, Johan; Erni, Rolf; Bals, Sara; Luysberg, M.; Dyck, D. Van; Tendeloo, Gustaaf Van

doi:10.1016/j.ultramic.2009.05.010

Cited by 205 publications

(165 citation statements)

References 31 publications

Supporting

Mentioning

164

Contrasting

Unclassified

Order By: Relevance

“…Several schemes for quantitative analysis of annular dark field (ADF) images have been proposed. LeBeau et al [44] have used the maximum pixel intensity in the vicinity of the centroid of each atom image, while Van Aert et al [45] assume the intensity of each atom column is a cylindrically symmetric two-dimensional (2D) Gaussian and perform a least-squares fit. Neither of these is appropriate for the current case, where unresolved oxygen atoms lie close to the metal atoms; rather, we use intensities integrated over a Voronoi cell surrounding the atom column of interest.…”

Section: Introductionmentioning

confidence: 99%

Atomic structure study of the pyrochloreYb2Ti2O7and its relationship with low-temperature magnetic order

et al. 2017

View full text Add to dashboard Cite

There has been great interest in the magnetic behavior of pyrochlore oxides with the general formula A 2 B 2 O 7 , in which rare-earth (A) and transition metal (B) cations are ordered on separate interpenetrating lattices of corner-sharing tetrahedra. Such materials exhibit behaviors including quantum spin-ice, (quantum) spin-liquid, and ordered magnetic ground states. Yb 2 Ti 2 O 7 lies on the boundary between a number of competing magnetic ground states. Features in the low-temperature specific heat capacity that vary in sharpness and temperature from sample to sample suggest that, in some cases, the magnetic moments order, while in others, the moments remain dynamic down to temperatures as low as ∼16 mK. In this paper, three different Yb 2 Ti 2 O 7 samples, all grown by the optical floating zone technique but exhibiting quite different heat capacity behavior, are studied by aberration-corrected scanning transmission microscopy (STEM). Atomic-scale energy-dispersive x-ray analysis shows that a crystal with no specific heat anomaly has substitution of Yb atoms on Ti sites (stuffing). We show that the detailed intensity distribution around the visible atomic columns in annular dark field STEM images is sensitive to the presence of nearby atoms of low atomic number (in this case oxygen) and find significant differences between the samples that correlate both with their magnetic behavior and measurements of Ti oxidation state using electron energy loss spectroscopy. These measurements support the view that the magnetic ground state of Yb 2 Ti 2 O 7 is extremely sensitive to disorder.

show abstract

Section: Introductionmentioning

confidence: 99%

Atomic structure study of the pyrochloreYb2Ti2O7and its relationship with low-temperature magnetic order

et al. 2017

View full text Add to dashboard Cite

show abstract

“…using the standard Levenberg-Marquart L 2 -norm minimization method, similar to the methods of Van Aert et al [12]. x and y are the positions for the intensity I, and the fitted parameters are I 0 , A, x w , y w , x 0 , y 0 , and c. A Gaussian function was chosen for the fitting because the shape of the atomic column images is dominated by the incoherent source broadening, which is well approximated by a Gaussian function [13,14].…”

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

View full text Add to dashboard Cite

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.

show abstract

“…Here we report the 3D reconstruction of a complex crystalline nanoparticle at atomic resolution. To achieve this, we combined aberration-corrected scanning transmission electron microscopy [5][6][7] , statistical parameter estimation theory 8,9 and discrete tomography 10,11 . Unlike conventional electron tomography, only two images of the target-a silver nanoparticle embedded in an aluminium matrix-are sufficient for the reconstruction when combined with available knowledge about the particle's crystallographic structure.…”

mentioning

confidence: 99%

“…Previous attempts have mostly focused on the technique and image acquisition, whereas the interpretation of the images was oversimplified, not taking into account the detailed probe characteristics [20][21][22] and the statistical nature of the experimental data. Here, we combine aberration-corrected HAADF STEM carried out under low voltage conditions with modelbased statistical parameter estimation 8,9 and discrete tomography 10,11 to obtain a full atomic-scale 3D reconstruction of an embedded nanoparticle.…”

mentioning

confidence: 99%

Three-dimensional atomic imaging of crystalline nanoparticles

Aert¹,

Bals²,

Batenburg³

et al. 2011

Acta Cryst Sect A

Self Cite

View full text Add to dashboard Cite

Determining the three-dimensional (3D) arrangement of atoms in crystalline nanoparticles is important for nanometre-scale device engineering and also for applications involving nanoparticles, such as optoelectronics or catalysis. A nanoparticle's physical and chemical properties are controlled by its exact 3D morphology, structure and composition 1 . Electron tomography enables the recovery of the shape of a nanoparticle from a series of projection images [2][3][4] . Although atomic-resolution electron microscopy has been feasible for nearly four decades, neither electron tomography nor any other experimental technique has yet demonstrated atomic resolution in three dimensions. Here we report the 3D reconstruction of a complex crystalline nanoparticle at atomic resolution. To achieve this, we combined aberration-corrected scanning transmission electron microscopy [5][6][7] , statistical parameter estimation theory 8,9 and discrete tomography 10,11 . Unlike conventional electron tomography, only two images of the target-a silver nanoparticle embedded in an aluminium matrix-are sufficient for the reconstruction when combined with available knowledge about the particle's crystallographic structure. Additional projections confirm the reliability of the result. The results we present help close the gap between the atomic resolution achievable in two-dimensional electron micrographs and the coarser resolution that has hitherto been obtained by conventional electron tomography.High-angle annular dark field scanning transmission electron microscopy (HAADF STEM) is an imaging technique in which a focused electron probe is scanned across an electron-transparent sample 12 .Using an annular-shaped high-angle detector behind the sample, the signal is dominated by Rutherford and thermal diffuse scattering. When applied to a nanocrystal in zone-axis orientation, the HAADF signal approximately scales with the square of the atomic number Z and with the thickness of the sample [13][14][15] . By using aberration-corrected probe forming optics [5][6][7] , a resolution of the order of 50 picometres can nowadays be demonstrated 16 . Therefore, it is generally believed that aberration-corrected HAADF STEM has the potential to achieve atomic resolution in three dimensions. Electron tomography is the most common approach used to reconstruct nanomaterials in three dimensions. The 3D reconstruction is computed from a tilt series of projection images acquired while rotating the sample. Spatial resolution for the reconstruction is around one cubic nanometre 2-4 , limiting its use for attaining atomic resolution. Another potential technique with which to obtain 3D structure information is 'depth-sectioning', in which a sample is optically sliced by changing the objective lens focus 17 . Single atoms can be visualized using this technique 18 , yet 3D reconstructions at atomic resolution have not been demonstrated because the depth resolution is insufficient to resolve interatomic distances along the optical axis. Discrete tomography, a recons...

show abstract

Quantitative atomic resolution mapping using high-angle annular dark field scanning transmission electron microscopy

Cited by 205 publications

References 31 publications

Atomic structure study of the pyrochloreYb2Ti2O7and its relationship with low-temperature magnetic order

Atomic structure study of the pyrochloreYb2Ti2O7and its relationship with low-temperature magnetic order

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

Three-dimensional atomic imaging of crystalline nanoparticles

Contact Info

Product

Resources

About