Development of a monochromator for aberration-corrected scanning transmission electron microscopy

Mukai, Masakazu; Okunishi, Eiji; Ashino, Masanori; Omoto, Kazuya; Fukuda, Tomohisa; Ikeda, Akihiro; Somehara, Kazunori; Kaneyama, T.; Saitoh, Takashi; Hirayama, Tsukasa; Ikuhara, Yuichi

doi:10.1093/jmicro/dfv001

Cited by 24 publications

(18 citation statements)

References 23 publications

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“…The energy spread of the incident electrons are typically ∆E~0.4 eV with a cold field emission gun, which is enough to perform core-loss EELS measurements. Recent progress on the monochromator of an electron source, the energy resolution is greatly improved up to 10-30 meV (10 times better than that of a cold field emission gun), which makes it possible to measure the local bandgap and phonon excitation (vibrational spectroscopy) [157,158]. The most limiting factor for atomic-resolution imaging was 3rd order spherical aberration but at the end of last century the combination of multi-pole lens system (quadra-octa poles or hexapole lens system) solved the problem, the invention of aberration correctors.…”

Section: Imaging and Spectroscopy By Atomic-resolution Stemmentioning

confidence: 99%

Influence of Dislocations in Transition Metal Oxides on Selected Physical and Chemical Properties

et al. 2018

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Studies on dislocations in prototypic binary and ternary oxides (here TiO 2 and SrTiO 3 ) using modern TEM and scanning probe microscopy (SPM) techniques, combined with classical etch pits methods, are reviewed. Our review focuses on the important role of dislocations in the insulator-to-metal transition and for redox processes, which can be preferentially induced along dislocations using chemical and electrical gradients. It is surprising that, independently of the growth techniques, the density of dislocations in the surface layers of both prototypical oxides is high (10 9 /cm 2 for epipolished surfaces and up to 10 12 /cm 2 for the rough surface). The TEM and locally-conducting atomic force microscopy (LCAFM) measurements show that the dislocations create a network with the character of a hierarchical tree. The distribution of the dislocations in the plane of the surface is, in principle, inhomogeneous, namely a strong tendency for the bundling and creation of arrays or bands in the crystallographic <100> and <110> directions can be observed. The analysis of the core of dislocations using scanning transmission electron microscopy (STEM) techniques (such as EDX with atomic resolution, electron-energy loss spectroscopy (EELS)) shows unequivocally that the core of dislocations possesses a different crystallographic structure, electronic structure and chemical composition relative to the matrix. Because the Burgers vector of dislocations is per se invariant, the network of dislocations (with additional d 1 electrons) causes an electrical short-circuit of the matrix. This behavior is confirmed by LCAFM measurements for the stoichiometric crystals, moreover a similar dominant role of dislocations in channeling of the current after thermal reduction of the crystals or during resistive switching can be observed. In our opinion, the easy transformation of the chemical composition of the surface layers of both model oxides should be associated with the high concentration of extended defects in this region. Another important insight for the analysis of the physical properties in real oxide crystals (matrix + dislocations) comes from the studies of the nucleation of dislocations via in situ STEM indentation, namely that the dislocations can be simply nucleated under mechanical stimulus and can be easily moved at room temperature.

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Section: Imaging and Spectroscopy By Atomic-resolution Stemmentioning

confidence: 99%

Influence of Dislocations in Transition Metal Oxides on Selected Physical and Chemical Properties

et al. 2018

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“…In this stable environment, a high energy resolution below 30 meV was achieved. 24 EELS spectra were recorded with an accelerating voltage of 60 kV to reduce irradiation damage and a convergence/collection semi-angle of 30/35 mrad. The energy resolution, DE, specified in terms of the FWHM of the zero-loss peak, was controlled by changing the width of an energy selection slit in the monochromator.…”

Section: Tem Specimens Of Thin Films Of Licopo 4 Limn 2 O 4 and LI mentioning

confidence: 99%

“…While measurements with resolutions up to 0.3 eV (as determined by the full width half maximum (FWHM) of the zero-loss peak) can be obtained using cold-FE guns, 21 to obtain resolutions better than 0.1 eV requires use of monochromators. [22][23][24] The latter allows Li-K edge spectra to be used to measure Li concentrations and distributions quantitatively with nanoscale resolution, as reported for materials LiCoO 2 , 25,26 LiFePO 4 27,28 and Li 2 MnO 3 . 29 One drawback of this method, however, is that TM-M 2,3 (or TM-N 2,3 ) edges lie near to Li-K edges, making their peaks difficult to deconvolute.…”

Section: Introductionmentioning

confidence: 98%

Systematic analysis of electron energy-loss near-edge structures in Li-ion battery materials

Saitoh

Gao

Ogawa

et al. 2018

Phys. Chem. Chem. Phys.

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“…Chemie then, researchers have worked to improve spatial resolution without sacrificing the energy resolution, [95][96][97][98][99][100][101][102][103][104] and the last five years have produced instruments with simultaneous % 5meV energy resolution and % 1 spatial resolution. [105,106] This new generation of instruments can be used to visualize and map nanoscale variations in previously inaccessible phenomena, such as surface phonon modes.…”

Section: Methodsmentioning

confidence: 99%

Emerging Electron Microscopy Techniques for Probing Functional Interfaces in Energy Materials

et al. 2019

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Interfaces play a fundamental role in many areas of chemistry. However, their localized nature requires characterization techniques with high spatial resolution in order to fully understand their structure and properties. State‐of‐the‐art atomic resolution or in situ scanning transmission electron microscopy and electron energy‐loss spectroscopy are indispensable tools for characterizing the local structure and chemistry of materials with single‐atom resolution, but they are not able to measure many properties that dictate function, such as vibrational modes or charge transfer, and are limited to room‐temperature samples containing no liquids. Here, we outline emerging electron microscopy techniques that are allowing these limitations to be overcome and highlight several recent studies that were enabled by these techniques. We then provide a vision for how these techniques can be paired with each other and with in situ methods to deliver new insights into the static and dynamic behavior of functional interfaces.

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Development of a monochromator for aberration-corrected scanning transmission electron microscopy

Cited by 24 publications

References 23 publications

Influence of Dislocations in Transition Metal Oxides on Selected Physical and Chemical Properties

Influence of Dislocations in Transition Metal Oxides on Selected Physical and Chemical Properties

Systematic analysis of electron energy-loss near-edge structures in Li-ion battery materials

Emerging Electron Microscopy Techniques for Probing Functional Interfaces in Energy Materials

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