skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: New insights into the negative thermal expansion: Direct experimental evidence for the “guitar-string” effect in cubic ScF 3

Abstract

The understanding of the negative thermal expansion (NTE) mechanism remains challenging but critical for the development of NTE materials. This study sheds light on NTE of ScF 3, one of the most outstanding materials with NTE. The local dynamics of ScF 3 has been investigated by a combined analysis of synchrotron-based X-ray total scattering, ex-tended X-ray absorption fine structure and neutron powder diffraction. Very interestingly, we observe that i) the Sc-F nearest-neighbor distance strongly expands with increasing temperature while the Sc-Sc next-nearest-neighbor distance contracts, ii) the thermal ellipsoids of relative vibrations be-tween Sc-F nearest-neighbors are highly elongated in the direction perpendicular to the Sc-F bond, indicating that the Sc-F bond is much softer to bend than to stretch, and iii) there is mainly dynamically transverse motion of fluorine atoms, rather than static shifts. Here, these results are the direct experimental evidence for the NTE mechanism, in which the rigid unit is not necessary for the occurrence of NTE, and the key role is played by the transverse thermal vibrations of fluorine atoms through the “guitar-string” effect.

Authors:
 [1];  [1];  [2];  [3];  [4];  [4];  [5];  [1];  [1];  [1]
  1. Univ. of Science and Technology Beijing, Beijing (China)
  2. Univ. of Padova, Padova (Italy)
  3. National Institute of Standards and Technology, Gaithersburg, MD (United States)
  4. Elettra Synchrotron, Triestre (Italy)
  5. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
National Natural Science Foundation of China (NNSFC); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division
OSTI Identifier:
1340686
Grant/Contract Number:
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 138; Journal Issue: 27; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Hu, Lei, Chen, Jun, Sanson, Andrea, Wu, Hui, Rodriguez, Clara Guglieri, Olivi, Luca, Ren, Yang, Fan, Longlong, Deng, Jinxia, and Xing, Xianran. New insights into the negative thermal expansion: Direct experimental evidence for the “guitar-string” effect in cubic ScF3. United States: N. p., 2016. Web. doi:10.1021/jacs.6b02370.
Hu, Lei, Chen, Jun, Sanson, Andrea, Wu, Hui, Rodriguez, Clara Guglieri, Olivi, Luca, Ren, Yang, Fan, Longlong, Deng, Jinxia, & Xing, Xianran. New insights into the negative thermal expansion: Direct experimental evidence for the “guitar-string” effect in cubic ScF3. United States. doi:10.1021/jacs.6b02370.
Hu, Lei, Chen, Jun, Sanson, Andrea, Wu, Hui, Rodriguez, Clara Guglieri, Olivi, Luca, Ren, Yang, Fan, Longlong, Deng, Jinxia, and Xing, Xianran. 2016. "New insights into the negative thermal expansion: Direct experimental evidence for the “guitar-string” effect in cubic ScF3". United States. doi:10.1021/jacs.6b02370. https://www.osti.gov/servlets/purl/1340686.
@article{osti_1340686,
title = {New insights into the negative thermal expansion: Direct experimental evidence for the “guitar-string” effect in cubic ScF3},
author = {Hu, Lei and Chen, Jun and Sanson, Andrea and Wu, Hui and Rodriguez, Clara Guglieri and Olivi, Luca and Ren, Yang and Fan, Longlong and Deng, Jinxia and Xing, Xianran},
abstractNote = {The understanding of the negative thermal expansion (NTE) mechanism remains challenging but critical for the development of NTE materials. This study sheds light on NTE of ScF3, one of the most outstanding materials with NTE. The local dynamics of ScF3 has been investigated by a combined analysis of synchrotron-based X-ray total scattering, ex-tended X-ray absorption fine structure and neutron powder diffraction. Very interestingly, we observe that i) the Sc-F nearest-neighbor distance strongly expands with increasing temperature while the Sc-Sc next-nearest-neighbor distance contracts, ii) the thermal ellipsoids of relative vibrations be-tween Sc-F nearest-neighbors are highly elongated in the direction perpendicular to the Sc-F bond, indicating that the Sc-F bond is much softer to bend than to stretch, and iii) there is mainly dynamically transverse motion of fluorine atoms, rather than static shifts. Here, these results are the direct experimental evidence for the NTE mechanism, in which the rigid unit is not necessary for the occurrence of NTE, and the key role is played by the transverse thermal vibrations of fluorine atoms through the “guitar-string” effect.},
doi = {10.1021/jacs.6b02370},
journal = {Journal of the American Chemical Society},
number = 27,
volume = 138,
place = {United States},
year = 2016,
month = 6
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 9works
Citation information provided by
Web of Science

Save / Share:
  • Materials that exhibit negative thermal expansion are of considerable scientific and technological interest. Their use in composites can facilitate the control of bulk thermal expansion properties to obtain a good match to other system components or zero expansion. Zero, or close to zero, thermal expansion is needed for various applications in optics, electronics, and other fields where exact positioning of parts is crucial. Nearly all materials that undergo negative thermal expansion display this property over a narrow temperature range or show anisotropic expansion behavior that can lead to microcracks. Recently, isotropic negative thermal expansion over the temperature range 0.3--1050 Kmore » has been reported for cubic ZrW{sub 2}O{sub 8} along with studies of its behavior under pressure. The structural similarity of many tungsten and molybdenum compounds strongly suggested the possibility of a cubic ZrMo{sub 2}O{sub 8} with related properties. Sleight and co-workers have recently prepared compositions in the solid solution ZrW{sub 2{minus}x}Mo{sub x}O{sub 8}, although they have been unable to make samples with x > 1.5. Here the authors report the first preparation and characterization of the end member cubic XrMo{sub 2}O{sub 8}.« less
  • Scandium trifluoride maintains a cubic ReO{sub 3} type structure down to at least 10 K, although the pressure at which its cubic to rhombohedral phase transition occurs drops from >0.5 GPa at {approx}300 K to 0.1-0.2 GPa at 50 K. At low temperatures it shows strong negative thermal expansion (NTE) (60-110 K, {alpha}{sub l} {approx} -14 ppm K{sup -1}). On heating, its coefficient of thermal expansion (CTE) smoothly increases, leading to a room temperature CTE that is similar to that of ZrW{sub 2}O{sub 8} and positive thermal expansion above {approx}1100 K. While the cubic ReO{sub 3} structure type is oftenmore » used as a simple illustration of how negative thermal expansion can arise from the thermally induced rocking of rigid structural units, ScF{sub 3} is the first material with this structure to provide a clear experimental illustration of this mechanism for NTE.« less
  • Cubic scandium trifluoride (ScF{sub 3}) has a large negative thermal expansion over a wide range of temperatures. Inelastic neutron scattering experiments were performed to study the temperature dependence of the lattice dynamics of ScF{sub 3} from 7 to 750 K. The measured phonon densities of states show a large anharmonic contribution with a thermal stiffening of modes around 25 meV. Phonon calculations with first-principles methods identified the individual modes in the densities of states, and frozen phonon calculations showed that some of the modes with motions of F atoms transverse to their bond direction behave as quantum quartic oscillators. Themore » quartic potential originates from harmonic interatomic forces in the DO{sub 9} structure of ScF{sub 3}, and accounts for phonon stiffening with the temperature and a significant part of the negative thermal expansion.« less
  • CaZrF6 and CaHfF6 display much stronger negative thermal expansion (NTE) (alpha(L100 K) similar to -18 and -22 ppm K-1, respectively) than ZrW2O8 and other corner-shared framework structures. Their NTE is comparable to that reported for framework solids containing multiatom bridges, such as metal cyanides and metal-organic frameworks. However, they are formable as ceramics, transparent over a wide wavelength range and can be handled in air; these characteristics can be beneficial for applications. The NTE of CaZrF6 is strongly temperature-dependent, and first-principles calculations show that it is largely driven by vibrational modes below similar to 150 cm(-1). CaZrF6 is elastically softmore » with a bulk modulus (K-300K) of 37 GPa and, upon compression, starts to disorder at similar to 400 MPa. The strong NTE of CaZrF6, which remains cubic to <10 K, contrasts with cubic CoZrF6, which only displays modest NTE above its rhombohedral to cubic phase transition at similar to 270 K. CaZrF6 and CaHfF6 belong to a large and compositionally diverse family of materials, A(II)B(IV)F(6), providing for a detailed exploration of the chemical and structural factors controlling NTE and many opportunities for the design of controlled thermal expansion materials.« less
  • No abstract prepared.