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Dielectric abnormity of Sr4Nd2Ti4Nb6O30 tungsten bronze ceramics over a broad temperature range

Published online by Cambridge University Press:  31 January 2011

X.L. Zhu
Affiliation:
Department of Material Science and Engineering, Zhejiang University, Hangzhou 310027, CHINA
X.M. Chen*
Affiliation:
Department of Material Science and Engineering, Zhejiang University, Hangzhou 310027, CHINA
X.Q. Liu
Affiliation:
Department of Material Science and Engineering, Zhejiang University, Hangzhou 310027, CHINA
*
a)Address all correspondence to this author. e-mail: [email protected].
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Abstract

In the present paper, Sr4Nd2Ti4Nb6O30 ceramics with filled tungsten bronze structure were prepared, and the dielectric characteristics over a broad temperature range (123 to 623 K) were investigated. Two dielectric abnormities were observed in the entire frequency range (100 Hz to 1 MHz). One is at higher temperature corresponding to a diffuse ferroelectric transition (P4/mbmP4bm), and the other at lower temperature shows relaxor characteristics in both ϵ′ and tan δ curves. An activation energy and freezing temperature of 0.1659 eV and 148.05 K, respectively, were obtained by analyzing the frequency dependence of the dielectric maximum temperature using the Vogel–Fulcher relationship. The relaxor behavior is attributed to a polar-glassy system with thermally activated polarization fluctuations above the freezing temperature. In addition, the dielectric constant was almost stable with both temperature and frequency in the temperature range of 300 to 430 K (between the two dielectric abnormities).

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Articles
Copyright
Copyright © Materials Research Society 2007

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