resumo
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 dieletric behavior 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 dispiacive modulations on the onset of relaxor/ferroelectric behavior 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.
palavras-chave
LEAD BARIUM NIOBATE; PBN SINGLE-CRYSTALS; DIELECTRIC-PROPERTIES; INCOMMENSURATE SUPERSTRUCTURES; PYROELECTRIC PROPERTIES; ELECTRICAL-PROPERTIES; PHASE-TRANSITION; RARE-EARTH; CERAMICS; SYSTEM
categoria
Chemistry; Materials Science
autores
Zhu, X; Fu, M; Stennett, MC; Vilarinho, PM; Levin, I; Randall, CA; Gardner, J; Morrison, FD; Reaney, IM
nossos autores
Paula Maria Lousada Silveirinha Vilarinho
Vice-Diretoragradecimentos
Ian M. Reaney acknowledges the support of the National Institute of Standards and Technology Visiting Scientist program.