Synthesis and ferroelectric properties of rare earth compounds with tungsten bronze-type structure

• Published in: Materials chemistry and physics 2011-10, Vol.129 (3), p.673-677
• Main Authors: Bouziane, M., Taibi, M., Boukhari, A.
• Format: Article
• Language: English
• Subjects: A. Ceramics; B. Heat treatment; BRONZES; C. DSC; C. X-ray scattering; CURIE TEMPERATURE; D. Dielectric properties; Diffraction; ELECTRICAL PROPERTIES; Ferroelectric materials; Ferroelectricity; Hysteresis; MECHANICAL HYSTERESIS; Rare earth compounds; RARE EARTHS; Tungsten; X RAYS
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2011.06.009

• Polycrystalline materials with the tungsten bronze-type structure have been synthesized and characterized. • Effect of the incorporation of rare earth ions and paramagnetic cations (Fe 3+) into a matrix ferroelectrically active was studied. • Ferroelectric transition is pronounced by a large thermal hysteresis during the heating and cooling cycles. • Phase transitions around T c were confirmed by differential scanning calorimetry (DSC) measurements. Polycrystalline materials with a general formula Pb 2Na 0.8R 0.2Nb 4.8Fe 0.2O 15 (R = Dy, Eu, Sm, Nd, La) have been synthesized, in air by a high temperature solid state reaction method. X-ray diffraction study, at room temperature, revealed that they crystallize in the tungsten bronze-type structure. Dielectric properties were performed, in the temperature range 25–500 °C, at three different frequencies 10, 100 and 1000 kHz. The ferroelectric transition is pronounced by a large thermal hysteresis during the heating and cooling cycles. The determined Curie temperature values T c were discussed as a function of rare earth size. Phase transitions around T c for the investigated compounds were confirmed by differential scanning calorimetry (DSC) measurements.