Atomic-Resolution Imaging of Oxygen in Perovskite Ceramics

Jia, Chun‐Lin; Lentzen, Markus; Urban, K.

doi:10.1126/science.1079121

Cited by 554 publications

(291 citation statements)

References 20 publications

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“…Another method of reducing the nonlinear image contrast is the adoption of negative Cs values, as proposed by the Juelich group [16]. In this case, an ordinary linear term has a positive contrast (white contrast in a bright-field image), which is in agreement with white nonlinear image contrast.…”

Section: Removal Of Nonlinear Image Contrast By Subtraction Methodssupporting

confidence: 55%

“…We can identify Mg atomic columns throughout the area and also the oxygen columns between them [15]. In this observation, we have chosen a positive Cs value in contrast with the data obtained by the Juelich group for SrTiO 3 crystals [16]. The present image shows the distribution of the image contrast, which may be connected with the distribution of projected potentials along the oxygen atomic columns under appropriate imaging conditions.…”

Section: Discrimination Of Elements By Cs-corrected Temmentioning

confidence: 41%

“…The present image shows the distribution of the image contrast, which may be connected with the distribution of projected potentials along the oxygen atomic columns under appropriate imaging conditions. Images obtained by the Juelich group are only sharp peaks resulting from the channeling phenomenon of electrons along the highly-symmetrical crystal axis [16].…”

Section: Discrimination Of Elements By Cs-corrected Temmentioning

confidence: 99%

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Present status and future prospects of spherical aberration corrected TEM/STEM for study of nanomaterials^∗

Tanaka

2008

Science and Technology of Advanced Materials

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The present status of Cs-corrected TEM/STEM is described from the viewpoint of the observation of nanomaterials. Characteristic features in TEM and STEM are explained using the experimental data obtained by our group and other research groups. Cs correction up to the 3rd-order aberration of an objective lens has already been established and research interest is focused on correcting the 5th-order spherical aberration and the chromatic aberration in combination with the development of a monochromator below an electron gun for smaller point-to-point resolution in optics. Another fundamental area of interest is the limitation of TEM and STEM resolution from the viewpoint of the scattering of electrons in crystals. The minimum size of the exit-wave function below samples undergoing TEM imaging is determined from the calculation of scattering around related atomic columns in the crystals. STEM does not have this limitation because the resolution is, in principle, determined by the probe size. One of the future prospects of Cs-corrected TEM/STEM is the possibility of extending the space around the sample holder by correcting the chromatic and spherical aberrations. This wider space will contribute to the ease of performing in situ experiments and various combinations of TEM and other analysis methods. High-resolution, in situ dynamic and 3D observations/analysis are the most important keywords in the next decade of high-resolution electron microscopy.

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Section: Removal Of Nonlinear Image Contrast By Subtraction Methodssupporting

confidence: 55%

Section: Discrimination Of Elements By Cs-corrected Temmentioning

confidence: 41%

Section: Discrimination Of Elements By Cs-corrected Temmentioning

confidence: 99%

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Present status and future prospects of spherical aberration corrected TEM/STEM for study of nanomaterials^∗

Tanaka

2008

Science and Technology of Advanced Materials

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“…1d) with an average diameter of 6.9±1.4 nm. Figure 1e shows an atomic resolution TEM image of one Pd-W particle using the negative Cs imaging technique 31 . The bright spots in the image are atom columns, while the amorphous area around is attributed to the OMCs support.…”

Section: Resultsmentioning

confidence: 99%

Small palladium islands embedded in palladium–tungsten bimetallic nanoparticles form catalytic hotspots for oxygen reduction

Nitze

Gracia‐Espino

et al. 2014

Nat Commun

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The sluggish kinetics of the oxygen reduction reaction at the cathode side of proton exchange membrane fuel cells is one major technical challenge for realizing sustainable solutions for the transportation sector. Finding efficient yet cheap electrocatalysts to speed up this reaction therefore motivates researchers all over the world. Here we demonstrate an efficient synthesis of palladium-tungsten bimetallic nanoparticles supported on ordered mesoporous carbon. Despite a very low percentage of noble metal (palladium:tungsten ¼ 1:8), the hybrid catalyst material exhibits a performance equal to commercial 60% platinum/Vulcan for the oxygen reduction process. The high catalytic efficiency is explained by the formation of small palladium islands embedded at the surface of the palladium-tungsten bimetallic nanoparticles, generating catalytic hotspots. The palladium islands are B1 nm in diameter, and contain 10-20 palladium atoms that are segregated at the surface. Our results may provide insight into the formation, stabilization and performance of bimetallic nanoparticles for catalytic reactions.

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“…Defects and interfaces can be studied without the image delocalization that normally complicates interpretation when imaging with a highcoherence FEG electron source [14,20]. Negative spherical aberration together with slight overfocus has been shown to yield images with bright-atom contrast, also allowing the degree of oxygenvacancy ordering and oxygen concentrations at twin boundaries to be determined [21]. Despite these promising advances and further intriguing possibilities, it cannot be overlooked, however, that image interpretation for these 'corrected' TEM imaging conditions remains far from intuitive [22].…”

mentioning

confidence: 99%

Progress and Perspectives for Atomic-Resolution Electron Microscopy

Smith

2005

MAM

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The atomic-resolution capabilities of the electron microscope, which first became widely accessible in the 1980s, have had a major impact across many disciplines [1]. With carefully prepared samples and correct operating conditions, assisted by quantitative image recording and processing, image characteristics can be interpreted directly in terms of individual atomic columns. With improvements in hardware and special attention to microscope environment, resolving powers close to or exceeding the one Ångstrom (0.1nm) barrier have been achieved by the latest generation of high-voltage HREMs [2][3][4]. Similar performance levels have been reached by dedicated scanning and conventional medium-voltage instruments [5,6], while sub-Ångstrom electron microscopy to resolutions of close to 0.8 nm has since been achieved using exit-wave retrieval [7,8]. Meanwhile, after a relatively dormant period during much of the 1990s, the last several years have witnessed a veritable explosion of further instrumentation hardware, including the successful implementation of aberration correctors for both conventional [9] and scanning [10] TEMs, as well as the design of electron monochromators which provide reduced energy spread and hence improved source coherence [11]. These latest developments have generated great interest and enthusiasm within the microscopy community, as well as attracting much attention from the broader materials community, especially for potential applications related to the rapidly emerging fields of nanoscience and nanotechnology.All electron lenses suffer from performance-limiting aberrations that must be removed in order to attain theoretical resolution limits. Two-fold astigmatism and third-order axial coma can be corrected manually by an experienced operator but for improved reliability and greater accuracy, online computer control or 'autotuning' of the microscope based, for example, on automated diffractogram analysis is recommended [12]. With the advent of aberration correctors, digital acquisition via slowscan CCD cameras has become indispensable. Computer analysis and control of corrector power supplies is essential for determining and then correcting most aberrations up to fourth order, including three-fold objective lens astigmatism and spherical aberration [13,14]. In the case of the probe-forming lens of the STEM, correction of the aberrations is done using multiple quadrupoleoctopole elements following analysis of a Ronchigram or shadow image obtained from a thin amorphous film [10,13]. For conventional TEM imaging, aberration correction is achieved with a double hexapole system and utilizes a tilt series of diffractograms, again relying on the availability of a thin amorphous film [14]. Aberration correction can also be tackled using a posteriori methods, such as exit-wave reconstruction based on through-focal image-series [7,8]. Similar resolution enhancements have been achieved using atomic-resolution electron holography [15]. Chromatic aberration remains as a serious obstacle to achievement of d...

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Atomic-Resolution Imaging of Oxygen in Perovskite Ceramics

Cited by 554 publications

References 20 publications

Present status and future prospects of spherical aberration corrected TEM/STEM for study of nanomaterials^∗

Present status and future prospects of spherical aberration corrected TEM/STEM for study of nanomaterials^∗

Small palladium islands embedded in palladium–tungsten bimetallic nanoparticles form catalytic hotspots for oxygen reduction

Progress and Perspectives for Atomic-Resolution Electron Microscopy

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Atomic-Resolution Imaging of Oxygen in Perovskite Ceramics

Cited by 554 publications

References 20 publications

Present status and future prospects of spherical aberration corrected TEM/STEM for study of nanomaterials∗

Present status and future prospects of spherical aberration corrected TEM/STEM for study of nanomaterials∗

Small palladium islands embedded in palladium–tungsten bimetallic nanoparticles form catalytic hotspots for oxygen reduction

Progress and Perspectives for Atomic-Resolution Electron Microscopy

Contact Info

Product

Resources

About

Present status and future prospects of spherical aberration corrected TEM/STEM for study of nanomaterials^∗

Present status and future prospects of spherical aberration corrected TEM/STEM for study of nanomaterials^∗