Dielectric and ferroelectric properties of Sr4CaSmTi3Nb7O30 with tetragonal tungsten bronze structure

• Published in: 中国物理B：英文版 no. 9; pp. 451 - 454
• Main Author: 龚高尚 方玉娇 黄帅 尹重阳 袁松柳 王丽光
• Format: Journal Article
• Language: English
• Published: 01.09.2014
• Subjects: 介电性能; 冷却过程; 差示扫描量热法; 微观尺度; 成分变化; 钨青铜结构; 铁电性质; 阳离子
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/23/9/097701

Sr4CaSmTi3Nb7O30 ceramics are synthesized and indexed as tetragonal tungsten bronze structure. The dielectric behavior and ferroelectric nature are investigated. Three dielectric anomalies are observed. The phase transition is a displacive phase transition with some diffusive characteristics, which indicates possible compositional variations within the materials on the microscopic scale. The weak distortion disappears in cooling process for differential scanning calorimetry measurement, and the large depression of Curie-Weiss temperature TO indicates the difficulty in forming macroferroelectric domain. The ferroelectric nature in these filled tungsten bronze niobates originates from the off-center displacement of B-site cations, but they are primarily dominated by A-site cation occupation. Both the radius and the valence of A1-site cations play an important role on ferroelectric properties of the filled tungsten bronze compounds. Existence of spontaneous polarization with a remanent polarization of 0.16 μC/cm^2 a coercive field of Ec = 11.74 kV/cm confirms the room-temperature ferroelectric nature of Sr4CaSmTi3Nb7O30 ceramics.