四角乌青铜结构的Sr4CaSmTi3Nb7O30陶瓷的介电与铁电性研究(1).doc


Dielectric and ferroelectric properties of
Sr4CaSmTi3Nb7O30 with tetragonal tungsten bronze
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Gong Gaoshang, Fang Yujiao, Huang Shuai, Yin Chongyang, Yuan Songliu, Wang
Liguang**
(School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, People’s
Republic of China)
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Abstract:
Sr4CaSmTi3Nb7O30 ceramics were synthesized and indexed as tetragonal tungsten
bronze structure. The dielectric behavior and ferroelectric nature were investigated. Three dielectric
anomalies were observed. The phase transition is a displacive phase transition with some diffusive
characteristic, which indicates positional variations within the materials in the microscopic
scale. The weak distortion disappears on cooling process for differential scanning calorimetry
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measurement and the large depression of Curie-Weiss temperature T0 indicate the difficulty in forming
of macroferroelectric domain. The ferroelectric nature in these filled tungsten bronze niobates
originates from the off-center displacement of B-site cations, but they primarily dominated by A site
cations occupation. Both the radius and the valence of A1 site cations play important roles on
ferroelectric properties of the filled tungsten pounds. Existence of spontaneous polarization
with Pr = and Ec = confirms the room temperature ferroelectric