'Soft' phonon modes, structured diffuse scattering and the crystal chemistry of Fe-bearing sphalerites
Journal Article
·
· Journal of Solid State Chemistry
- Research School of Chemistry, Australian National University, Canberra, ACT, 0200 (Australia)
- Mineralogy Department, South Australian Museum, Adelaide, South Australia (Australia)
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 {l_brace}110{r_brace}* 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 <110> real space directions of the average structure are suggested to be responsible for these {l_brace}110{r_brace}* 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 <110> real space directions.
- OSTI ID:
- 20725820
- Journal Information:
- Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 3 Vol. 178; ISSN 0022-4596; ISSN JSSCBI
- Country of Publication:
- United States
- Language:
- English
Similar Records
Three-dimensional mapping of diffuse scattering in Pb(Zn{sub 1/3}Nb{sub 2/3})O{sub 3}-xPbTiO{sub 3}
Local crystal chemistry, structured diffuse scattering and the dielectric properties of (Bi{sub 1-} {sub x} Y {sub x} ){sub 2}(M {sup III}Nb{sup V})O{sub 7} (M=Fe{sup 3+}, In{sup 3+}) Bi-pyrochlores
Structured diffuse scattering and polar nano-regions in the Ba(Ti{sub 1-} {sub x} Sn {sub x} )O{sub 3} relaxor ferroelectric system
Journal Article
·
Sun Oct 31 23:00:00 EST 2004
· Physical Review. B, Condensed Matter and Materials Physics
·
OSTI ID:20664942
Local crystal chemistry, structured diffuse scattering and the dielectric properties of (Bi{sub 1-} {sub x} Y {sub x} ){sub 2}(M {sup III}Nb{sup V})O{sub 7} (M=Fe{sup 3+}, In{sup 3+}) Bi-pyrochlores
Journal Article
·
Tue Aug 15 00:00:00 EDT 2006
· Journal of Solid State Chemistry
·
OSTI ID:20905401
Structured diffuse scattering and polar nano-regions in the Ba(Ti{sub 1-} {sub x} Sn {sub x} )O{sub 3} relaxor ferroelectric system
Journal Article
·
Thu Mar 15 00:00:00 EDT 2007
· Journal of Solid State Chemistry
·
OSTI ID:21015722