A quantitative measure of medium-range order in amorphous materials from transmission electron micrographs

Dash, Raj Kishora; Voyles, Paul M.; Gibson, J. M.; Treacy, M.M.J.; Keblinski, Pawel

doi:10.1088/0953-8984/15/31/317

Cited by 35 publications

(32 citation statements)

References 32 publications

(46 reference statements)

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“…The second peak also covers the Al ͗311͘ at 0.82 Å −1 . Figure 3 shows V͑k͒ simulated for both a 30 Å diameter crystalline Al sphere and icosehedron of 12 Al atoms surrounding a Sm atom 12 using an extension of the Dash et al 13 4 Sm sphere simulations ͑not shown͒ fail to reproduce even the experimental peak positions.…”

mentioning

confidence: 99%

Aluminum nanoscale order in amorphous Al92Sm8 measured by fluctuation electron microscopy

Stratton

Hamann

Perepezko

et al. 2005

Applied Physics Letters

103

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When annealed below T g , the melt-spun material exhibits a steadily decreasing nucleation rate, 4 which suggests heterogeneous nucleation. 5 The nucleation site has so far eluded structural or chemical detection, ruling out common sites like second phase interfaces or large impurity clusters. This suggests that the nucleation sites in quenched Al 92 Sm 8 may be a form of nanometer-length structure or medium-range order ͑MRO͒. Such structure is difficult to detect in amorphous materials using conventional techniques such as x-ray diffraction. 6 Here, we report fluctuation electron microscopy ͑FEM͒ ͑Refs. 7 and 8͒ measurements and simulations which find MRO associated with primary crystallization in amorphous Al 92 Sm 8 .FEM measures diffraction from nanoscale volumes using dark-field transmission electron microscopy ͑TEM͒ at a deliberately low ͑5-50 Å͒ image resolution. The magnitude of the spatial fluctuations in diffraction, measured by the normalized variance V as a function of scattering vector k, gives information about MRO at the length scale of the image resolution. 7,9 V͑k͒ depends on the three-and four-body atomic position correlation functions. 9 Peaks in V͑k͒ give information about the type of MRO from their position in k and the degree of MRO from their height. A polycrystalline sample is an extreme example of order: in a dark-field image each grain will appear brightest when it satisfies a Bragg condition in k, leading to a high peaks in V͑k͒ at the crystal reciprocal lattice k's.Samples of amorphous Al 92 Sm 8 were prepared by rapid quenching in a single wheel melt spinner at a tangential wheel speed of 55 m / s and by cold-rolling elemental foil multilayers at a 0.003 s −1 strain rate. Melt-spun ribbon samples were annealed at 130°C ͑ϽT g of 171°C͒ 3,10 under vacuum. TEM samples were prepared by electropolishing only, as ion milling can introduce spurious peaks in V͑k͒ of amorphous metals. 11 FEM was done in hollow-cone darkfield mode on a LEO 912 EFTEM at 120 kV and 16 Å resolution. Each V͑k͒ data set is the mean of measurements from at least seven areas of the sample, quoted with one standard deviation of the mean error bars.

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mentioning

confidence: 99%

Aluminum nanoscale order in amorphous Al92Sm8 measured by fluctuation electron microscopy

Stratton

Hamann

Perepezko

et al. 2005

Applied Physics Letters

103

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“…We note, however, that for paracrystalline models decreasing of the real-space resolution has only minor effect on the correlation length (see Ref. [25] for details).…”

Section: Radial Distribution Function Revisitedmentioning

confidence: 87%

“…The three synthesized PC models have grain diameters of 1.3, 1.6, and 1.9 nm, and are labeled Para1, Para2, and Para3, as in our prior publication [25]. In each case, the grains occupy $50% of the volume of the model, so the larger grain models contain more atoms.…”

Section: Model Descriptionmentioning

confidence: 99%

“…A detailed description of such calculations is presented in Ref. [25]. An example of a calculated image is presented in the top panel of Fig.…”

Section: Tem Image Analysismentioning

confidence: 99%

“…3) for each of the model structures compare well (Table 1). We need to note that the correlation length derived from images is dependent on the microscope resolution, which is proportional to the aperture reciprocal radius Q [25]. The presented values are for a simulated real space resolution of about 11 Å .…”

Section: Radial Distribution Function Revisitedmentioning

confidence: 99%

See 2 more Smart Citations

Medium range order and the radial distribution function

Bodapati

Treacy

Falk

et al. 2006

Journal of Non-Crystalline Solids

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Fluctuation Electron Microscopy

Voyles

Hwang

2012

Characterization of Materials

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Fluctuation electron microscopy (FEM) is a nanodiffraction technique for measuring nanometer scale order in amorphous materials. Either dark‐field transmission electron microscope imaging or coherent electron nanodiffraction in a scanning transmission electron microscope is used to measure the diffracted intensity from the sample with nanometer spatial resolution. Fluctuations in that intensity from place to place on the sample reveal the size, density, and internal atomic arrangements of nanometer‐scale order. Nanometer scale order in glasses is also called medium‐range order (MRO). Fluctuation microscopy is one of the few experimental techniques sensitive to this type of structure in amorphous materials.

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A quantitative measure of medium-range order in amorphous materials from transmission electron micrographs

Cited by 35 publications

References 32 publications

Aluminum nanoscale order in amorphous Al92Sm8 measured by fluctuation electron microscopy

Aluminum nanoscale order in amorphous Al92Sm8 measured by fluctuation electron microscopy

Medium range order and the radial distribution function

Fluctuation Electron Microscopy

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