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‘Soft’ phonon modes,structured diffuse scattering and the crystal chemistry of Fe-bearing sphalerites

Withers, Ray L. and Welberry, T.R. and Pring, Allan and Tenailleau, Christophe and Liu, Yun ‘Soft’ phonon modes,structured diffuse scattering and the crystal chemistry of Fe-bearing sphalerites. (2005) Journal of Solid State Chemistry, 178 (3). 655-660. ISSN 0022-4596

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Official URL: http://dx.doi.org/10.1016/j.jssc.2004.12.011


Electron diffraction has been used to carefully investigate the reciprocal lattices of a range of iron-bearing sphalerites looking for evidence of Fe clustering and/or Fe/Zn ordering in the form of either additional satellite reflections or a structured diffuse intensity distribution accompanying the strong Bragg reflections of the underlying sphalerite-type average structure. While a highly structured diffuse intensity distribution in the form of transverse polarized f110g sheets of diffuse intensity has been detected and found to be characteristic of all compositions,it does not appear to arise from Fe clustering and/or Fe/Zn ordering. Rather inherently low frequency,and therefore strongly thermally excited,phonon modes propagating along reciprocal space directions perpendicular to each of the six /110S real space directions of the average structure are suggested to be responsible for these f110g sheets of diffuse intensity. Monte Carlo simulation (for a range of Zn–S,Zn–Zn and S–S interaction strengths) and subsequent Fourier transformation is used to confirm the existence of these low-frequency phonon modes of distortion as well as to show that they are an intrinsic,predictable property of the corner-connected tetrahedral structure of sphalerite. The low-frequency phonon modes involve coupled (Zn,Fe) and S motion in one-dimensional strings along /110S real space directions.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at Journal of Solid State Chemistry website : http://www.sciencedirect.com/science/journal/00224596
Audience (journal):International peer-reviewed journal
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Institution:Other partners > South Australian Museum (AUSTRALIA)
Other partners > Australian National University - ANU (AUSTRALIA)
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Deposited On:01 Jul 2010 07:07

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