New Gadolinium Based Ferroelectric Phases Derived from the Tetragonal Tungsten Bronze (TTB)
Substitution of Pb with Gd in the Pb2KNb5O15 phases leads to a new composition of solid solution with chemical composition Pb2(1 − x)GdxK1 + xNb5O15 (0 ≤ x ≤ 1) which crystallizes with TTB type structure. Powders are pressed and heated into ceramics and their compaction is about 90%. Thermal evolution of the real part of the dielectric permittivity presents different behavior according to the composition. The dielectric permittivity of compounds with Gd composition above x = 0.30 shows two anomalies. The first one appears at TC and is associated to the ferroelectric-paraelectric phase transition. The origin of the last one at which occurs at T1 is up to now unknown. Domain structure should exhibit strong changes both with temperature and composition.
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Document Type: Research Article
Faculty of Sciences, University Cadi Ayyad, Laboratory of Mineral Solid State Chemistry, Bd. My Abdallah, B.P. 2390, Marrakech (Morocco)
Faculty of Sciences and Technics, University Cadi Ayyad, B.P. 549, Marrakech (Morocco)
University of Toulon and Var, L2MP(UMR CNRS 6137), 83957 La Garde, France
Publication date: January 1, 2003