中国物理B ›› 2019, Vol. 28 ›› Issue (9): 98202-098202.doi: 10.1088/1674-1056/ab37f1

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

Structural and dielectric properties of giant dielectric Na1/2Sm1/2Cu3Ti4O12 ceramics prepared by reactive sintering methods

H Mahfoz Kotb   

  1. 1 Department of Physics, College of Science, King Faisal University, Al-Hassa 31982, Saudi Arabia;
    2 Department of Physics, Faculty of Science, Assiut University, Assiut 71516, Egypt
  • 收稿日期:2019-03-12 修回日期:2019-07-17 出版日期:2019-09-05 发布日期:2019-09-05
  • 通讯作者: H Mahfoz Kotb E-mail:hkotb@kfu.edu.sa

Structural and dielectric properties of giant dielectric Na1/2Sm1/2Cu3Ti4O12 ceramics prepared by reactive sintering methods

H Mahfoz Kotb1,2   

  1. 1 Department of Physics, College of Science, King Faisal University, Al-Hassa 31982, Saudi Arabia;
    2 Department of Physics, Faculty of Science, Assiut University, Assiut 71516, Egypt
  • Received:2019-03-12 Revised:2019-07-17 Online:2019-09-05 Published:2019-09-05
  • Contact: H Mahfoz Kotb E-mail:hkotb@kfu.edu.sa

摘要:

Na0.5Sm0.5Cu3Ti4O12 (NSCTO) ceramics have been prepared by reactive sintering of amorphous powder. Spark plasma sintering (SPS) for 10 min at 1025℃ and conventional sintering (CS) for 10 h at 1090℃ have been employed. X-ray diffraction measurements confirmed the pure CCTO-like phase for SPS and CS NSCTO ceramics. The SPS ceramic showed an average grain size of 500 nm, which is much smaller than that of the CS (~5 μm) sample. The impedance spectroscopy measurements revealed an electrically inhomogeneous structure in the prepared ceramics. While the resistivities of grains of both ceramic samples were in the same order of magnitude, the resistivity of grain-boundaries of the CS ceramic was three orders of magnitude greater than that of the SPS ceramic. Both of the samples showed giant dielectric constant (>103) over wide ranges of temperatures and frequencies. Nevertheless, the room-temperature dielectric loss of the SPS NSCTO (3.2 at 1.1 kHz) ceramic sample was higher than that of the CS NSCTO (0.08 at 1.1 kHz) ceramic sample due to the reduced grain-boundary resistivity of the former. Two dielectric relaxations were detected for each sample and attributed to the relaxations in grains and grain-boundaries. The dielectric behavior of the SPS and CS NSCTO ceramics could be interpreted in terms of the internal barrier layer capacitor (IBLC) model.

关键词: ceramics, sintering, dielectric loss and relaxation

Abstract:

Na0.5Sm0.5Cu3Ti4O12 (NSCTO) ceramics have been prepared by reactive sintering of amorphous powder. Spark plasma sintering (SPS) for 10 min at 1025℃ and conventional sintering (CS) for 10 h at 1090℃ have been employed. X-ray diffraction measurements confirmed the pure CCTO-like phase for SPS and CS NSCTO ceramics. The SPS ceramic showed an average grain size of 500 nm, which is much smaller than that of the CS (~5 μm) sample. The impedance spectroscopy measurements revealed an electrically inhomogeneous structure in the prepared ceramics. While the resistivities of grains of both ceramic samples were in the same order of magnitude, the resistivity of grain-boundaries of the CS ceramic was three orders of magnitude greater than that of the SPS ceramic. Both of the samples showed giant dielectric constant (>103) over wide ranges of temperatures and frequencies. Nevertheless, the room-temperature dielectric loss of the SPS NSCTO (3.2 at 1.1 kHz) ceramic sample was higher than that of the CS NSCTO (0.08 at 1.1 kHz) ceramic sample due to the reduced grain-boundary resistivity of the former. Two dielectric relaxations were detected for each sample and attributed to the relaxations in grains and grain-boundaries. The dielectric behavior of the SPS and CS NSCTO ceramics could be interpreted in terms of the internal barrier layer capacitor (IBLC) model.

Key words: ceramics, sintering, dielectric loss and relaxation

中图分类号:  (Ceramics in electrochemistry)

  • 82.45.Xy
81.20.Ev (Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation) 77.22.Gm (Dielectric loss and relaxation) 84.37.+q (Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.))