Low energy phonons in the NTE compounds Zn (CN)2 and ZnPt (CN)6

Karena W. Chapman; Mark Hagen; Cameron J. Kepert; Pascal Manuel

doi:10.1016/j.physb.2006.05.102

Low energy phonons in the NTE compounds Zn (CN)₂ and ZnPt (CN)₆

Karena W. Chapman
, Mark Hagen
, Cameron J. Kepert
, Pascal Manuel

Chemistry

Australian Nuclear Science and Technology Organisation
The University of Sydney
Harwell Campus

Research output: Contribution to journal › Article › peer-review

34 Scopus citations

Abstract

The compounds Zn (CN)₂ and ZnPt (CN)₆ both display negative thermal expansion (NTE) properties, that is to say they undergo a volume contraction with increasing temperature. In the case of Zn (CN)₂ this volume contraction occurs over a temperature range from 25 to 375 K with a coefficient of thermal expansion α = - 16.9 (2) × 10^{- 6} K^{- 1} [A.L. Goodwin, C.J. Kepert, Phys. Rev. B 71 (2005) 14030]. This phenomenon is believed to be related to the presence of low energy rigid unit modes (RUMS) in the phonon dispersion relations of Zn (CN)₂ [A.L. Goodwin, C.J. Kepert, Phys. Rev. B 71 (2005) 14030]. We have examined the low energy part of the phonon density of states in Zn (CN)₂ and ZnPt (CN)₆ using time of flight inelastic neutron scattering from powder samples. In Zn (CN)₂ there is a strong peak in the density of states at 2 meV whose temperature dependence can be correlated with that of α. There is a similar peak in the density of states of ZnPt (CN)₆ at 7.5 meV, which correlates with the smaller NTE effect in this compound.

Original language	English
Pages (from-to)	60-62
Number of pages	3
Journal	Physica B: Condensed Matter
Volume	385-386 I
DOIs	https://doi.org/10.1016/j.physb.2006.05.102
State	Published - Nov 27 2006

Keywords

Inelastic neutron scattering
Negative thermal expansion
Rigid unit modes

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title = "Low energy phonons in the NTE compounds Zn (CN)2 and ZnPt (CN)6",

abstract = "The compounds Zn (CN)2 and ZnPt (CN)6 both display negative thermal expansion (NTE) properties, that is to say they undergo a volume contraction with increasing temperature. In the case of Zn (CN)2 this volume contraction occurs over a temperature range from 25 to 375 K with a coefficient of thermal expansion α = - 16.9 (2) × 10- 6 K- 1 [A.L. Goodwin, C.J. Kepert, Phys. Rev. B 71 (2005) 14030]. This phenomenon is believed to be related to the presence of low energy rigid unit modes (RUMS) in the phonon dispersion relations of Zn (CN)2 [A.L. Goodwin, C.J. Kepert, Phys. Rev. B 71 (2005) 14030]. We have examined the low energy part of the phonon density of states in Zn (CN)2 and ZnPt (CN)6 using time of flight inelastic neutron scattering from powder samples. In Zn (CN)2 there is a strong peak in the density of states at 2 meV whose temperature dependence can be correlated with that of α. There is a similar peak in the density of states of ZnPt (CN)6 at 7.5 meV, which correlates with the smaller NTE effect in this compound.",

keywords = "Inelastic neutron scattering, Negative thermal expansion, Rigid unit modes",

author = "Chapman, \{Karena W.\} and Mark Hagen and Kepert, \{Cameron J.\} and Pascal Manuel",

year = "2006",

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doi = "10.1016/j.physb.2006.05.102",

language = "English",

volume = "385-386 I",

pages = "60--62",

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T1 - Low energy phonons in the NTE compounds Zn (CN)2 and ZnPt (CN)6

AU - Chapman, Karena W.

AU - Hagen, Mark

AU - Kepert, Cameron J.

AU - Manuel, Pascal

PY - 2006/11/27

Y1 - 2006/11/27

N2 - The compounds Zn (CN)2 and ZnPt (CN)6 both display negative thermal expansion (NTE) properties, that is to say they undergo a volume contraction with increasing temperature. In the case of Zn (CN)2 this volume contraction occurs over a temperature range from 25 to 375 K with a coefficient of thermal expansion α = - 16.9 (2) × 10- 6 K- 1 [A.L. Goodwin, C.J. Kepert, Phys. Rev. B 71 (2005) 14030]. This phenomenon is believed to be related to the presence of low energy rigid unit modes (RUMS) in the phonon dispersion relations of Zn (CN)2 [A.L. Goodwin, C.J. Kepert, Phys. Rev. B 71 (2005) 14030]. We have examined the low energy part of the phonon density of states in Zn (CN)2 and ZnPt (CN)6 using time of flight inelastic neutron scattering from powder samples. In Zn (CN)2 there is a strong peak in the density of states at 2 meV whose temperature dependence can be correlated with that of α. There is a similar peak in the density of states of ZnPt (CN)6 at 7.5 meV, which correlates with the smaller NTE effect in this compound.

AB - The compounds Zn (CN)2 and ZnPt (CN)6 both display negative thermal expansion (NTE) properties, that is to say they undergo a volume contraction with increasing temperature. In the case of Zn (CN)2 this volume contraction occurs over a temperature range from 25 to 375 K with a coefficient of thermal expansion α = - 16.9 (2) × 10- 6 K- 1 [A.L. Goodwin, C.J. Kepert, Phys. Rev. B 71 (2005) 14030]. This phenomenon is believed to be related to the presence of low energy rigid unit modes (RUMS) in the phonon dispersion relations of Zn (CN)2 [A.L. Goodwin, C.J. Kepert, Phys. Rev. B 71 (2005) 14030]. We have examined the low energy part of the phonon density of states in Zn (CN)2 and ZnPt (CN)6 using time of flight inelastic neutron scattering from powder samples. In Zn (CN)2 there is a strong peak in the density of states at 2 meV whose temperature dependence can be correlated with that of α. There is a similar peak in the density of states of ZnPt (CN)6 at 7.5 meV, which correlates with the smaller NTE effect in this compound.

KW - Inelastic neutron scattering

KW - Negative thermal expansion

KW - Rigid unit modes

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DO - 10.1016/j.physb.2006.05.102

M3 - Article

AN - SCOPUS:33751333502

SN - 0921-4526

VL - 385-386 I

SP - 60

EP - 62

JO - Physica B: Condensed Matter

JF - Physica B: Condensed Matter

ER -

Low energy phonons in the NTE compounds Zn (CN)₂ and ZnPt (CN)₆

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