Derivation of Inter-Atomic Force Constants of Cu&lt;sub&gt;2&lt;/sub&gt;O from Diffuse Neutron Scattering Measurement

Makhsun, T.; Sakuma, Takashi; Kartini, Evvy; Sakai, Ryutaro; Takahashi, Hiroki; Igawa, Naoki; Danilkin, Sergey

doi:10.17146/aij.2013.217

Cited by 2 publications

(3 citation statements)

References 16 publications

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“…The mean values of the effective force constants obtained from DINS experiments in Ni 44 Nb 56 compare favourably with the values reported in the literature for other glassy systems and parent compounds (e.g. metal oxides) used for glass synthesis [43,[103][104][105][106][107][108][109][110][111]. They yield 0.75 eV Å 2, and 0.91 eV Å 2 in the case of nickel and niobium, respectively, and are equal to the average force constant values, calculated based on the ab initio HLD simulations for crystals of nickel, niobium and NiNb.…”

Section: Resultssupporting

confidence: 84%

Force constant disorder in the Ni₄₄Nb₅₆ bulk metallic glass as observed by deep inelastic neutron scattering augmented by isotopic substitution

et al. 2022

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In this work, the force-constant disorder in nickel-niobium metallic glass, Ni44Nb56, was studied using the deep inelastic neutron scattering (DINS) technique augmented by isotopic substitution. The distributions of DINS observables (the nuclear kinetic energies, the width of the nuclear momentum distributions, and the effective force constants) were measured in Ni44Nb56 and compared with their counterparts obtained from ab initio harmonic lattice (HLD) simulations for the crystalline forms of nickel, niobium, and the NiNb crystal and from the reverse Monte Carlo (RMC) simulations augmented by effective force fields performed for Ni44Nb56. The force-constant distribution of nickel, obtained from the analysis of the results of the DINS experiments, was found to be two times broader than its counterparts estimated based on the HLD and RMC simulations. In the case of niobium, the force-constant distribution inferred from the DINS experiments is estimated to be an order of magnitude broader than the ab initio HLD prediction in the NiNb crystal. Moreover, no disorder-induced softening (with respect to its crystalline counterparts) of the effective force constants of Ni and Nb in Ni44Nb56 was observed. The lack of disorder-induced softening in Ni44Nb56 is consistent with the correlation between the short-range order, defined by the average coordination number and the interatomic distances, and the magnitudes of the effective force constants. The obtained results are consistent with a picture, whereby disorder induces symmetrical broadening of phonon dispersion curves, and phonon softening is limited to low-energy modes carrying negligible amounts of nuclear kinetic energy. The obtained results have important ramifications for engineering the properties of bulk metallic glasses.

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Section: Resultssupporting

confidence: 84%

Force constant disorder in the Ni₄₄Nb₅₆ bulk metallic glass as observed by deep inelastic neutron scattering augmented by isotopic substitution

et al. 2022

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“…Specifically, the Sakuma modeling uniquely enables the retrieval of information concerning the local dynamic structure, encoded within the correlation coefficients (λ r ss ′ ). The λ r ss ′ parameters are proportional to the coordination number (CN) of each shell and to the force constants of the material and inversely proportional to their pair distance r . ,, The λ r ss ′ relation with the CN is visible at low r , giving oscillatory trends in Figure a when comparing the yellow bars (CN) with the solid lines of the λ r ss ′ coefficients. This behavior stems from the fact that a larger number of atoms within a given shell results in greater forces acting on the individual atom, thus intensifying the correlation motion that draws the atoms toward the respective shell.…”

Section: Resultsmentioning

confidence: 99%

“…If the same structure is made of a different element, different force constants between each atomic pair will be present, reducing or increasing the λ r ss ′ modulus for the stiffer or softer bonding of this new element. Equations relating the correlation coefficient with the force constants are given by Sakuma et al , Nevertheless, for stronger atomic bonds and closer pair distances, the correlation coefficients should be higher (maximum 1) and tend to zero for large r values due to the reduction of the forces between the pair of atoms at larger distances. The λ r ss ′ coefficients, retrieved from the Sakuma modeling of the TDS for the simulated nanospheres, are plotted in Figure for the three temperatures considered, 298, 200, and 100 K (respectively a, b, and c, in Figure ).…”

Section: Resultsmentioning

confidence: 99%

Thermal Diffuse Scattering from Nanocrystalline Systems

Scardi,

Malagutti

2024

Crystal Growth & Design

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The thermal diffuse scattering (TDS) in X-ray diffraction (XRD) patterns contains significant information about the local lattice dynamic structure of nanocrystalline systems. Techniques such as the pair distribution function (PDF) are commonly employed to extract this information, where the correlated movement of atomic pairs remains encoded in the breadths of the PDF peaks. However, PDF techniques require a Fourier transformation of the experimental XRD data, orientationally averaging the local dynamic information, rendering it not readily distinguishable from the static component and crystallite size and shape effects. Herein, we explore the possibility of an analysis of local lattice dynamics based directly on XRD powder pattern modeling, where TDS is added to the structural model of the traditional Rietveld method. Allied with the whole powder pattern modeling approach, the crystallite shape and static components are simultaneously estimated. Two study cases of Pd nanocrystalline systems are analyzed: (i) in silico nanosphere powder simulations via molecular dynamics (MD) and (ii) synchrotron radiation XRD powder patterns of Pd nanocubes. In silico analysis points out that the TDS model provides the correct trends of the correlated atomic movement up to the ninth coordination shell. The experimental case shows that this TDS model correctly estimates the force mechanisms of the nanocrystalline Pd system. We believe that the established method and the obtained results in this study broaden the application scope of XRD for studying the dynamic properties of nanocrystalline materials.

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Derivation of Inter-Atomic Force Constants of Cu<sub>2</sub>O from Diffuse Neutron Scattering Measurement

Cited by 2 publications

References 16 publications

Force constant disorder in the Ni₄₄Nb₅₆ bulk metallic glass as observed by deep inelastic neutron scattering augmented by isotopic substitution

Force constant disorder in the Ni₄₄Nb₅₆ bulk metallic glass as observed by deep inelastic neutron scattering augmented by isotopic substitution

Thermal Diffuse Scattering from Nanocrystalline Systems

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Derivation of Inter-Atomic Force Constants of Cu<sub>2</sub>O from Diffuse Neutron Scattering Measurement

Cited by 2 publications

References 16 publications

Force constant disorder in the Ni44Nb56 bulk metallic glass as observed by deep inelastic neutron scattering augmented by isotopic substitution

Force constant disorder in the Ni44Nb56 bulk metallic glass as observed by deep inelastic neutron scattering augmented by isotopic substitution

Thermal Diffuse Scattering from Nanocrystalline Systems

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Product

Resources

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Force constant disorder in the Ni₄₄Nb₅₆ bulk metallic glass as observed by deep inelastic neutron scattering augmented by isotopic substitution

Force constant disorder in the Ni₄₄Nb₅₆ bulk metallic glass as observed by deep inelastic neutron scattering augmented by isotopic substitution