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arXiv · 1508.05909

Design of crystal-like aperiodic solids with selective disorder--phonon coupling

Alistair R. Overy·Andrew B. Cairns·Matthew J. Cliffe·Matthew G. Tucker·Andrew L. Goodwin
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Abstract

Functional materials design normally focuses on structurally-ordered systems because disorder is considered detrimental to many important physical properties. Here we challenge this paradigm by showing that particular types of strongly-correlated disorder can give rise to useful characteristics that are inaccessible to ordered states. A judicious combination of low-symmetry building unit and high-symmetry topological template leads to aperiodic "procrystalline" solids that harbour this type of topological disorder. We identify key classes of procrystalline states together with their characteristic diffraction behaviour, and establish a variety of mappings onto known and target materials. Crucially, the strongly-correlated disorder we consider is associated with specific sets of modulation periodicities distributed throughout the Brillouin zone. Lattice dynamical calculations reveal selective disorder-phonon coupling to lattice vibrations characterised by these same periodicities. The principal effect on the phonon spectrum is to bring about dispersion in energy rather than wave-vector, as in the poorly-understood "waterfall" effect observed in relaxor ferroelectrics. This property of procrystalline solids suggests a mechanism by which strongly-correlated topological disorder might allow new and useful functionalities, including independently-optimised thermal and electronic transport behaviour as required for high-performance thermoelectrics.

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Alistair R. Overy, Andrew B. Cairns, Matthew J. Cliffe, Matthew G. Tucker, Andrew L. Goodwin. 2015-08-24. Design of crystal-like aperiodic solids with selective disorder--phonon coupling. https://doi.org/10.1038/ncomms10445

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