Tungsten Bronze Barium Neodymium Titanate (Ba6–3nNd8+2nTi18O54): An Intrinsic Nanostructured Material and Its Defect Distribution

Azough, Feridoon; Cernik, Robert J.; Schaffer, Bernhard; Kepaptsoglou, Demie; Ramasse, Quentin M.; Bigatti, Marco; Almasi‐Hashiani, Amir; MacLaren, Ian; Barthel, Juri; Molinari, Marco; Baran, Jakub D.; Parker, Stephen C.; Freer, Robert

doi:10.1021/acs.inorgchem.5b02594

Cited by 18 publications

(14 citation statements)

References 45 publications

(151 reference statements)

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“…In figure 1a the most obvious of these is the elongation of the La columns in the LFO layer. This suggests a "zig-zagging" of the La atoms along the beam direction, resulting in "elliptical" atomic columns as seen previously by Azough et al [21]. Fitting 2D Gaussians to every A-site atomic column using the Atomap software [18] yields a map of the ellipticity of the A-cations (La and Sr columns) as shown in Figure 1b, revealing a distinct ellipticity in the LFO, not observed in the STO or the LSMO.…”

Section: Resultssupporting

confidence: 62%

“…Large electron doses can often alter the oxide, and recent work has shown that beam damage to perovskites happens well before it is obvious in high-resolution images [20]. In some cases, 3D information can also be inferred from the shape of the columns in 2 dimensions [10,18,21]. An important drawback for this strategy is that the method requires both very high quality TEM-samples, an optimized aberration corrected STEM and a high degree of post processing to reduce the effects of scanning distortions [22,23].…”

Section: Introductionmentioning

confidence: 99%

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Three-dimensional subnanoscale imaging of unit cell doubling due to octahedral tilting and cation modulation in strained perovskite thin films

Nord

Ross

McGrouther

et al. 2019

Phys. Rev. Materials

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Determining the 3-dimensional crystallography of a material with sub-nanometre resolution is essential to understanding strain effects in epitaxial thin films. A new scanning transmission electron microscopy imaging technique is demonstrated that visualises the presence and strength of atomic movements leading to a period doubling of the unit cell along the beam direction, using the intensity in an extra Laue zone ring in the back focal plane recorded using a pixelated detector method. This method is used together with conventional atomic resolution imaging in the plane perpendicular to the beam direction to gain information about the 3D crystal structure in an epitaxial thin film of LaFeO3 sandwiched between a substrate of (111) SrTiO3 and a top layer of La0.7Sr0.3MnO3. It is found that a hitherto unreported structure of LaFeO3 is formed under the unusual combination of compressive strain and (111) growth, which is triclinic with a periodicity doubling from primitive perovskite along one of the three <110> directions lying in the growth plane. This results from a combination of La-site modulation along the beam direction, and modulation of oxygen positions resulting from octahedral tilting. This transition to the perioddoubled cell is suppressed near both the substrate and near the La0.7Sr0.3MnO3 top layer due to the clamping of the octahedral tilting by the absence of tilting in the substrate and due to an incompatible tilt pattern being present in the La0.7Sr0.3MnO3 layer. This work shows a rapid and easy way of scanning for such transitions in thin films or other systems where disorder-order transitions or domain structures may be present and does not require the use of atomic resolution imaging, and could be done on any scanning TEM instrument equipped with a suitable camera. I.

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Section: Resultssupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Three-dimensional subnanoscale imaging of unit cell doubling due to octahedral tilting and cation modulation in strained perovskite thin films

Nord

Ross

McGrouther

et al. 2019

Phys. Rev. Materials

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“…This type of analysis is best suited for monocrystalline materials, especially epitaxial thin films and heterostructures, or polycrystalline materials with large grains (e.g., domain-structured functional oxides with different orientations of the principal axes of the cell), as the technique requires the crystal to be imaged along a zone axis. While it may be performed at atomic resolution, this is not necessary, and this technique has the advantage that it yields information about the modulation of atomic positions along a column without requiring atomic resolution, as demonstrated in previous analyses of this effect (Borisevich et al, 2010; Azough et al, 2016).…”

Section: Higher-order Laue Zone Analysismentioning

confidence: 99%

Fast Pixelated Detectors in Scanning Transmission Electron Microscopy. Part II: Post-Acquisition Data Processing, Visualization, and Structural Characterization

et al. 2020

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“…domain-structured functional oxides with different orientations of the principal axes of the cell), as the technique requires the crystal to be imaged along a zone axis. Whilst it may be performed at atomic resolution, this is not necessary, and this technique has the advantage that it yields information about the modulation of atomic positions along a column without requiring atomic resolution, as demonstrated in previous analyses of this effect (Azough et al, 2016;Borisevich et al, 2010).…”

Section: Higher Order Laue Zone Analysismentioning

confidence: 99%

Fast Pixelated Detectors in Scanning Transmission Electron Microscopy. Part II: Post Acquisition Data Processing, Visualisation, and Structural Characterisation

Paterson,

Webster,

Ross

et al. 2020

Preprint

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Fast pixelated detectors incorporating direct electron detection (DED) technology are increasingly being regarded as universal detectors for scanning transmission electron microscopy (STEM), capable of imaging under multiple modes of operation. However, several issues remain around the post acquisition processing and visualisation of the often very large multidimensional STEM datasets produced by them. We discuss these issues and present open source software libraries to enable efficient processing and visualisation of such datasets. Throughout, we provide examples of the analysis methodologies presented, utilising data from a 256×256 pixel Medipix3 hybrid DED detector, with a particular focus on the STEM characterisation of the structural properties of materials. These include the techniques of virtual detector imaging; higher order Laue zone analysis; nanobeam electron diffraction; and scanning precession electron diffraction. In the latter, we demonstrate nanoscale lattice parameter mapping with precision in the low to mid 10 −4 (10 −2 %), a value comparable to the best ones reported elsewhere.

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Tungsten Bronze Barium Neodymium Titanate (Ba_6–3nNd_8+2nTi₁₈O₅₄): An Intrinsic Nanostructured Material and Its Defect Distribution

Cited by 18 publications

References 45 publications

Three-dimensional subnanoscale imaging of unit cell doubling due to octahedral tilting and cation modulation in strained perovskite thin films

Three-dimensional subnanoscale imaging of unit cell doubling due to octahedral tilting and cation modulation in strained perovskite thin films

Fast Pixelated Detectors in Scanning Transmission Electron Microscopy. Part II: Post-Acquisition Data Processing, Visualization, and Structural Characterization

Fast Pixelated Detectors in Scanning Transmission Electron Microscopy. Part II: Post Acquisition Data Processing, Visualisation, and Structural Characterisation

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