Structural and electrical properties of Na2Pb2Eu2W2Ti4X4O30 (X = Nb, Ta) ferroelectric ceramics

A new group of tungsten bronze family Na2Pb2Eu2W2Ti4X4O30 (X = Nb, Ta) having all the valence elements (I-VI) were prepared by a high-temperature solid-state reaction technique. The formations of the compounds were confirmed by X-ray diffraction technique with an orthorhombic structure. Surface morphology of the compounds was studied by scanning electron microscope (SEM). Studies of dielectric properties (epsilon(r) and tan delta) of the above compounds at different frequencies in a wide temperature range (300-700 K) with an impedance analyzer exhibit a ferroelectric phase transition at 580 and 394 K for Na2Pb2Eu2W2Ti4Nb4O30 and Na2Pb2Eu2W2Ti4TaO30, respectively. Ferroelectric properties of these compounds were confirmed with polarization (hysteresis) study. (C) 2009 Elsevier Ltd. All rights reserved.