›› 2014, Vol. 23 ›› Issue (12): 128701-128701.doi: 10.1088/1674-1056/23/12/128701

• INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY • 上一篇    下一篇

Effects of A1 site occupation on dielectric and ferroelectric properties of Sr4CaRTi3Nb7O30 (R=Ce, Eu) tungsten bronze ceramics

方玉娇, 龚高尚, Gebru Zerihun, 袁松柳   

  1. School of Physics, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
  • 收稿日期:2014-05-22 修回日期:2014-06-25 出版日期:2014-12-15 发布日期:2014-12-15
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 11174092) and the Key Project of Henan Provincial Educational Committee, China (Grant No. 14A140019).

Effects of A1 site occupation on dielectric and ferroelectric properties of Sr4CaRTi3Nb7O30 (R=Ce, Eu) tungsten bronze ceramics

Fang Yu-Jiao (方玉娇), Gong Gao-Shang (龚高尚), Gebru Zerihun, Yuan Song-Liu (袁松柳)   

  1. School of Physics, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
  • Received:2014-05-22 Revised:2014-06-25 Online:2014-12-15 Published:2014-12-15
  • Contact: Yuan Song-Liu E-mail:yuansl@hust.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 11174092) and the Key Project of Henan Provincial Educational Committee, China (Grant No. 14A140019).

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摘要： Sr4CaRTi3Nb7O30 (R=Ce, Eu) tungsten bronze ceramics are prepared by a standard solid state reaction method. The effects of A1 site occupation on the dielectric and ferroelectric properties of Sr4CaRTi3Nb7O30 (R=Ce, Eu) tetragonal tungsten bronzes are investigated. The Sr4CaCeTi3Nb7O30 shows a normal transition behavior due to the closer size ion occupation in A1 sites, which could suppress the distortion of B2 octahedra effectively. Sr4CaEuTi3Nb7O30 ceramic exhibits two dielectric anomalies, which might be related to the fact that the large radius difference between Ca2+ and Eu3+ could lead to the uneven distribution of Ca2+ and Eu3+ in A1 sites and form two slightly different kinds of compositions with different transition temperatures in the structure. Our results indicate that the ionic radius difference in A1 sites plays an important role in determining the dielectric and ferroelectric natures of the filled tungsten bronze ceramics. Polarization–electric field (P–E) curves are evaluated at room temperature and both of them show hysteresis loops. Sr4CaCeTi3Nb7O30 shows a fat hysteresis loop, indicating the long-range ferroelectric order in the ceramic. The current density–electric field (J–E) curves are measured at room temperature with a largest leakage current density of ～ 10-6 A/cm2, indicating that their leakage currents are rather low.

关键词: dielectric anomaly, relaxation, ferroelectricity

Abstract: Sr4CaRTi3Nb7O30 (R=Ce, Eu) tungsten bronze ceramics are prepared by a standard solid state reaction method. The effects of A1 site occupation on the dielectric and ferroelectric properties of Sr4CaRTi3Nb7O30 (R=Ce, Eu) tetragonal tungsten bronzes are investigated. The Sr4CaCeTi3Nb7O30 shows a normal transition behavior due to the closer size ion occupation in A1 sites, which could suppress the distortion of B2 octahedra effectively. Sr4CaEuTi3Nb7O30 ceramic exhibits two dielectric anomalies, which might be related to the fact that the large radius difference between Ca2+ and Eu3+ could lead to the uneven distribution of Ca2+ and Eu3+ in A1 sites and form two slightly different kinds of compositions with different transition temperatures in the structure. Our results indicate that the ionic radius difference in A1 sites plays an important role in determining the dielectric and ferroelectric natures of the filled tungsten bronze ceramics. Polarization–electric field (P–E) curves are evaluated at room temperature and both of them show hysteresis loops. Sr4CaCeTi3Nb7O30 shows a fat hysteresis loop, indicating the long-range ferroelectric order in the ceramic. The current density–electric field (J–E) curves are measured at room temperature with a largest leakage current density of ～ 10-6 A/cm2, indicating that their leakage currents are rather low.

Key words: dielectric anomaly, relaxation, ferroelectricity

中图分类号:  (Dielectric properties)

  • 87.19.rf
31.70.Hq (Time-dependent phenomena: excitation and relaxation processes, and reaction rates) 77.84.-s (Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials)