Controlling microstructure and significantly increased dielectric permittivity with largely reduced dielectric loss in C
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Controlling microstructure and significantly increased dielectric permittivity with largely reduced dielectric loss in CaCu3−xGexTi4O12 ceramics Jakkree Boonlakhorn1 · Narong Chanlek2 · Pornjuk Srepusharawoot3 · Prasit Thongbai1,3 Received: 15 June 2020 / Accepted: 12 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Microstructure, dielectric, and electrical properties of CaCu3−xGexTi4O12 ceramics with x = 0–0.10 prepared by a conventional solid-state reaction method are investigated. Single-phase of CaCu3Ti4O12 was detected in all sintered ceramics. u2+ sites results in the grain size of C aCu3−xGexTi4O12 ceramics to decrease, compared to The substitution of G e4+ into C CaCu3Ti4O12 ceramic. Unusually, although grain sizes of CaCu3−xGexTi4O12 ceramics decrease, their dielectric permittivity is increased by doping. Enhanced dielectric permittivity ~ 35,000–42,000 with reduced loss tangent ~ 0.037–0.053 was achieved in x = 0.025–0.10. Improved dielectric properties with reduced loss tangent might be originated by enhanced grain boundary response, especially the largely increased grain boundary resistance. The result obtained from an impedance spectroscopy technique indicates the formation of an internal barrier layer capacitor model in all sintered ceramics. The giant dielectric permittivity of CaCu3−xGexTi4O12 ceramics might be caused by intrinsically compensating mechanisms of charge carriers. Keywords CaCu3Ti4O12 · Giant/colossal dielectric properties · Impedance spectroscopy · IBLC · XPS
1 Introduction Due to the extensive development of electronic devices, lots of electronic materials have been widely studied and reported over the past decade [1–18]. CaCu3Ti4O12 (CCTO) perovskite ceramic is also chosen to study and improve its dielectric and electrical properties for use in electronic and energy storage applications [1–5, 8–12]. The attracting points of CCTO ceramic for researchers are its high dielectric permittivity (ε′) ~ 103–105 without the influence of ferroelectric behavior owing to phase transition [18]. Besides, nonlinear electrical properties could also be detected in this * Prasit Thongbai [email protected] 1
Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand
2
Synchrotron Light Research Institute (Public Organization), 111 University Avenue, Muang District, Nakhon Ratchasima 30000, Thailand
3
Institute of Nanomaterials Research and Innovation for Energy (IN‑RIE), NANOTEC ‑KKU RNN On Nanomaterials Research and Innovation for Energy, Khon Kaen University, Khon Kaen 40002, Thailand
ceramic [14]. Hence, many research clusters have investigated its properties for use in electronic applications, especially capacitors and varistors [1–5]. Even though the origin of the giant dielectric response observed in CCTO ceramic is not formed by the ferroelectric actions, the possible origin has been unclear. The widely accepted model for describing a huge dielectric response in CCTO ceramic is an internal barrie
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