Two-dimensional nanoscale correlations in the strong negative thermal expansion material 
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Handunkanda, Sahan; Occhialini, Connor A.; Said, Ayman; Hancock, Jason

doi:10.1103/physrevb.94.214102

Cited by 9 publications

(10 citation statements)

References 29 publications

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“…The second point is that the frequencies of phonons away from the M−R line increase rapidly with frequency, and these modes have low frequency only for wave vectors near this line in reciprocal space. Again, this point is consistent with the inelastic and diffuse scattering measurements [33,34].…”

Section: Background: Reciprocal-space Model Of Negative Thermal Esupporting

confidence: 90%

“…The eigenvectors of these modes correspond to transverse motions of the F atoms with whole-body rotations of the ScF 6 octahedra. Measurements of inelastic x-ray scattering [33] and diffuse x-ray scattering [34] from single crystals support this picture exactly. The second point is that the frequencies of phonons away from the M−R line increase rapidly with frequency, and these modes have low frequency only for wave vectors near this line in reciprocal space.…”

Section: Background: Reciprocal-space Model Of Negative Thermal Ementioning

confidence: 63%

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Quantitative understanding of negative thermal expansion in scandium trifluoride from neutron total scattering measurements

Dove

Wei

et al. 2020

Phys. Rev. B

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Negative thermal expansion (NTE)-the phenomenon where some materials shrink rather than expand when heated-is both intriguing and useful but remains poorly understood. Current understanding hinges on the role of specific vibrational modes, but in fact thermal expansion is a weighted sum of contributions from every possible mode. Here we overcome this difficulty by deriving a real-space model of atomic motion in the prototypical NTE material scandium trifluoride, ScF 3 , from total neutron scattering data. We show that NTE in this material depends not only on rigid unit modes-the vibrations in which the scandium coordination octahedra remain undistorted-but also on modes that distort these octahedra. Furthermore, in contrast with previous predictions, we show that the quasiharmonic approximation coupled with renormalization through anharmonic interactions describes this behavior well. Our results point the way towards a new understanding of how NTE is manifested in real materials.

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Section: Background: Reciprocal-space Model Of Negative Thermal Esupporting

confidence: 90%

Section: Background: Reciprocal-space Model Of Negative Thermal Ementioning

confidence: 63%

Quantitative understanding of negative thermal expansion in scandium trifluoride from neutron total scattering measurements

Dove

Wei

et al. 2020

Phys. Rev. B

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“…ScF 3 is an unusually clean material - single crystals have been synthesized with 0.002 degree mosaic (Handunkanda et al, 2016), free of color centers, with high chemical and isotopic purity with readily available components. The flexibility afforded by the trivalent B -site in the trifluorides permits wide chemical tunability and provides new opportunities to observe disorder effects on SNTE.…”

Section: The Role Of Disorder In Perovskite Snte Materialsmentioning

confidence: 99%

Negative Thermal Expansion Near the Precipice of Structural Stability in Open Perovskites

et al. 2018

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Negative thermal expansion (NTE) describes the anomalous propensity of materials to shrink when heated. Since its discovery, the NTE effect has been found in a wide variety of materials with an array of magnetic, electronic and structural properties. In some cases, the NTE originates from phase competition arising from the electronic or magnetic degrees of freedom but we here focus on a particular class of NTE which originates from intrinsic dynamical origins related to the lattice degrees of freedom, a property we term structural negative thermal expansion (SNTE). Here we review some select cases of NTE which strictly arise from anharmonic phonon dynamics, with a focus on open perovskite lattices. We find that NTE is often present close in proximity to competing structural phases, with structural phase transition lines terminating near T=0 K yielding the most prominent displays of the SNTE effect. We further provide a theoretical model to make precise the proposed relationship among the signature behavior of SNTE, the proximity of these systems to structural quantum phase transitions and the effects of phase fluctuations near these unique regions of the structural phase diagram. The effects of compositional disorder on NTE and structural phase stability in perovskites are discussed.

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“…Specifically, the 'central peak' phenomenon and a dispersionless branch of modes circumscribing the edges of the simple cubic Brillouin zone softens to zero temperature according to classical scaling and a putative transition temperature T =-39 K. The dispersionless nature of modes in one dimension of reciprocal space and observed diffuse X-ray scattering rods suggest a dimensional lowering in this system, permitting application of the 2D CLM [47]. We note the appearance of the system size in the expression for the lattice parameter (Eqn.…”

Section: Discussionmentioning

confidence: 91%

“…2D nanoscale correlations Recent inelastic X-ray scattering work [18,47] has shown that ScF 3 features an incipient soft mode instability via its excitation spectrum. Specifically, the 'central peak' phenomenon and a dispersionless branch of modes circumscribing the edges of the simple cubic Brillouin zone softens to zero temperature according to classical scaling and a putative transition temperature T =-39 K. The dispersionless nature of modes in one dimension of reciprocal space and observed diffuse X-ray scattering rods suggest a dimensional lowering in this system, permitting application of the 2D CLM [47].…”

Section: Discussionmentioning

confidence: 99%

Classical, quantum, and thermodynamics of a lattice model exhibiting structural negative thermal expansion

et al. 2017

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Two-dimensional nanoscale correlations in the strong negative thermal expansion material ScF3

Cited by 9 publications

References 29 publications

Quantitative understanding of negative thermal expansion in scandium trifluoride from neutron total scattering measurements

Quantitative understanding of negative thermal expansion in scandium trifluoride from neutron total scattering measurements

Negative Thermal Expansion Near the Precipice of Structural Stability in Open Perovskites

Classical, quantum, and thermodynamics of a lattice model exhibiting structural negative thermal expansion

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