Colossal dielectric response in erbium iron garnet ceramics
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Colossal dielectric response in erbium iron garnet ceramics Jia Zheng1, Qingshan Fu1, Xinghan Chen1, Chiranjib Chakrabarti1, Pengjian Wang1, Hongxia Yin1, Canglong Li2, Yang Qiu2, and Songliu Yuan1,* 1 2
School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China School of Physics and Electronic Engineering, Xinyang Normal University, Xinyang 464000, People’s Republic of China
Received: 31 July 2020
ABSTRACT
Accepted: 27 October 2020
Polycrystalline Er3Fe5O12 ceramic sample was synthesized by a solid-state reaction technique. The dielectric properties of the sample were experimentally studied. A colossal dielectric constant more than 103 was observed over a wide temperature and frequency range. The dielectric relaxation in the sample was identified by the measurement of permittivity modulus, impedance spectroscopy, and conductivity in detail. At relatively low temperatures (T \ 600 K), the dielectric relaxation under high frequencies (f C 50 kHz) is triggered by the dipolar effect accompanied by the Fe2? and Fe3? charge transitions, while that under low frequencies (f B 50 kHz) is mainly be associated with the Maxwell– Wagner effect. Moreover, a low-frequency dielectric relaxation at high temperatures (T C 600 K) is probably evolving from the contribution of oxygen vacancies and grain boundaries, which is also suggested to be the origin of the colossal dielectric constant.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Dielectric materials have various applications in electronics devices [1–5]. Among this kind of materials, the materials with colossal dielectric constants (CDC) higher than 103, which are also called giant dielectric materials, are considered to play significant roles in many microelectronics devices, for instance, the miniaturization of resonators, memories, and capacitors [6–10]. CaCu3Ti4O12 ceramics and the
Jia Zheng and Qingshan Fu have contributed equally to this work.
Address correspondence to E-mail: [email protected]
https://doi.org/10.1007/s10854-020-04775-9
relevant compounds have attracted increasing attention as giant dielectric materials with extremely large permittivity in the wide frequency and temperature ranges [7, 11, 12]. An internal barrier layer capacitor (IBLC) model was put forward to understand the unusual dielectric response of these materials, which suggests that the materials are composed of semiconductor-type grains and insulator-type grain boundaries [13–16]. It is well known that the rare-earth (Re)-type iron garnets with the general formula of Re3Fe5O12 are
J Mater Sci: Mater Electron
ferromagnetic insulators [17, 18]. Recently, Huang et al. reported that high-temperature dielectric properties of Sm3Fe5O12 ceramics show CDC in broad temperature and frequency ranges [18]. Moreover, Y3Fe5O12, Eu3Fe5O12, and Gd3Fe5O12 also present high dielectric permittivity above room temperature [17, 19, 20]. Although a number of giant dielectric materials have been found, the amount of
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