A crystal-chemical framework for relaxor versus normal ferroelectric behavior in tetragonal tungsten bronzes
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Tetragonal Tungsten Bronzes (TTBs) - an important class of oxides known to exhibit ferroelectricity - undergo complex distortions, including rotations of oxygen octahedra, which give rise to either incommensurately or commensurately modulated superstructures. Many TTBs display broad, frequency-dependent relaxor dielectric behaviour rather than sharper frequency-independent normal ferroelectric anomalies but the exact reasons that favor a particular type of dielectric response for a given composition remain unclear. In this contribution the influence of incommensurate/commensurate displacive modulations on the onset of relaxor/ferroelectric behaviour in TTBs is assessed in the context of basic crystal-chemical factors, such as positional disorder, ionic radii and polarizabilities, and point defects. We present a predictive crystal-chemical model that rationalizes composition-structure-properties relations for a broad range of TTB systems.
Zhu , X , Fu , M , Stennett , M C , Vilarinho , P M , Levin , I , Randall , C A , Gardner , J , Morrison , F & Reaney , I M 2015 , ' A crystal-chemical framework for relaxor versus normal ferroelectric behavior in tetragonal tungsten bronzes ' Chemistry of Materials , vol 27 , no. 9 , pp. 3250-3261 . DOI: 10.1021/acs.chemmater.5b00072
Chemistry of Materials
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Chemistry of Materials, copyright © 2015 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acs.chemmater.5b00072
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