 | Acta Crystallographica Section B Acta Crystallographica Section B STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS |
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![[Figure 5]](wu5006fig5mag.jpg)
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Figure 5
Effect of short-range compositional order on the phonon dispersion relations in KCl0.5Br0.5. Each panel shows the band-unfold SCLD projection ρ(k, ω) for key directions in reciprocal space and for different values of the short-range order parameter α. The W–Δ–W section shown on the right-hand side corresponds to the diffuse scattering cut used to calculate scattering peakwidths; its intersection with the Δ line is indicated by a dashed vertical line. The phonon dispersion relations for KCl and KBr are shown as red and blue lines, respectively. The virtual crystal approximation holds reasonably well for both α = −0.2 and 0: in most cases, the SCLD projection is well localised in both k and ω, and has its maxima at values intermediate to those for the KCl and KBr end-members. By contrast, the α = 0.8 projection shows very complex behaviour, with band-splitting and significant delocalisation in both k and ω. Note in particular the shallowness of the TA branch near ![[[{{1} \over {2}}{{1} \over {2}}0]]](teximages/wu5006fi7.svg) along the W–Δ–W line, which is responsible for the broader diffuse scattering measured experimentally. |
![[Figure 5]](wu5006fig5.jpg)
| STRUCTURAL SCIENCE CRYSTAL ENGINEERING MATERIALS |
ISSN: 2052-5206
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