The Disordered Crystal Structures of Zn(CN)2and Ga(CN)3

Williams, D. J.; Partin, D.E.; Lincoln, Francis; Kouvetakis, John; O’Keeffe, Michael

doi:10.1006/jssc.1997.7571

Cited by 104 publications

(147 citation statements)

References 13 publications

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“…To this end, strong covalent bonds are not indispensable. This point is exemplified by a series of cyanide-bridged compounds [24][25][26][27]. This class of materials exhibits the largest NTE in this category, i.e.…”

Section: Cyanidesmentioning

confidence: 99%

Negative thermal expansion materials: technological key for control of thermal expansion

Takenaka

2012

Science and Technology of Advanced Materials

489

311

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Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE) materials have enormous industrial merit because they can control the thermal expansion of materials. Recent progress in materials research enables us to obtain materials exhibiting negative coefficients of linear thermal expansion over −30 ppm K −1 . Such giant NTE is opening a new phase of control of thermal expansion in composites. Specifically examining practical aspects, this review briefly summarizes materials and mechanisms of NTE as well as composites containing NTE materials, based mainly on activities of the last decade.

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Section: Cyanidesmentioning

confidence: 99%

Negative thermal expansion materials: technological key for control of thermal expansion

Takenaka

2012

Science and Technology of Advanced Materials

489

311

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“…This type of bonding allows large transverse thermally excited motions of the bridging C/N atoms to occur in (M-CN-M) bridges within metal-cyanide frameworks. Structural studies [9] of Zn(CN) 2 show that two different models having cubic symmetry with space group Pn3m (disordered model) and P43m (ordered model), give equally good account of the diffraction data. The ordered structure ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Relationship between phonons and thermal expansion in Zn(CN)2and Ni(CN)2from inelastic neutron scattering andab initiocalculations

et al. 2011

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). We have measured the temperature dependence of phonon spectra in these compounds and analyzed them using ab-initio calculations. The spectra of the two compounds show large differences that cannot be explained by simple mass renormalization of the modes involving Zn (65.38 amu) and Ni (58.69 amu) atoms. This reflects the fact that the structure and bonding are quite different in the two compounds. The calculated pressure dependence of the phonon modes and of the thermal expansion coefficient, α V , are used to understand the anomalous behavior in these compounds. Our ab-initio calculations indicate that it is the low-energy rotational modes in Zn(CN) 2 , which are shifted to higher energies in Ni(CN) 2 , that are responsible for the large negative thermal expansion. The measured temperature dependence of the phonon spectra has been used to estimate the total anharmonicity of both compounds. For Zn(CN) 2 , the temperature-dependent measurements (total anharmonicity), along with our previously reported pressure dependence of the phonon spectra (quasiharmonic), is used to separate the explicit temperature effect at constant volume (intrinsic anharmonicity).

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“…The prototypical NTE ceramic is zirconium tungstate (ZrW 2 O 8 ) which displays a large, isotropic NTE of −9 p.p.m./K over a wide temperature range of 0.3-1050 K. 8 Since the discovery of NTE in ZrW 2 O 8 , a small number of NTE materials have been identified, such as LiAlSiO 4 , 9 (Zn,Cd)(CN) 2 , [10][11][12] and Mn 3 (Co(CN) 6 ) 2 , 13 which all possess flexible network structures. 14 In many of these materials, NTE has been explained using the theory of rigid unit modes (RUMs) 15 whereby the contraction of the material is driven by soft vibrations of approximately rigid polyhedral units.…”

Section: Introductionmentioning

confidence: 99%

The origin of uniaxial negative thermal expansion in layered perovskites

et al. 2017

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Why is it that ABO 3 perovskites generally do not exhibit negative thermal expansion (NTE) over a wide temperature range, whereas layered perovskites of the same chemical family often do? It is generally accepted that there are two key ingredients that determine the extent of NTE: the presence of soft phonon modes that drive contraction (have negative Grüneisen parameters); and anisotropic elastic compliance that predisposes the material to the deformations required for NTE along a specific axis. This difference in thermal expansion properties is surprising since both ABO 3 and layered perovskites often possess these ingredients in equal measure in their high-symmetry phases. Using first principles calculations and symmetry analysis, we show that in layered perovskites there is a significant enhancement of elastic anisotropy due to symmetry breaking that results from the combined effect of layering and condensed rotations of oxygen octahedra. This feature, unique to layered perovskites of certain symmetry, is what allows uniaxial NTE to persist over a large temperature range. This fundamental insight means that symmetry and the elastic tensor can be used as descriptors in high-throughput screening and to direct materials design.

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The Disordered Crystal Structures of Zn(CN)2and Ga(CN)3

Cited by 104 publications

References 13 publications

Negative thermal expansion materials: technological key for control of thermal expansion

Negative thermal expansion materials: technological key for control of thermal expansion

Relationship between phonons and thermal expansion in Zn(CN)2and Ni(CN)2from inelastic neutron scattering andab initiocalculations

The origin of uniaxial negative thermal expansion in layered perovskites

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