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Non-stoichiometry in "CaCu_(3)Ti_(4)O_(12)" (CCTO) ceramics

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Schmidt, Rainer and Pandey, Shubhra and Fiorenza, Patrick and Sinclair, Darek C. (2013) Non-stoichiometry in "CaCu_(3)Ti_(4)O_(12)" (CCTO) ceramics. RSC Advances, 3 (34). pp. 14580-14589. ISSN 2046-2069

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Official URL: http://dx.doi.org/10.1039/c3ra41319e


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Abstract

A combined powder X-ray lattice parameter and ceramic impedance spectroscopy study is presented on materials within the CaO–CuO–TiO_(2) ternary phase diagram. Several compositions containing CaCu_(3)Ti_(4)O_(12) (CCTO) and small amounts of secondary phases such as TiO_(2), CaTiO_(3) and CuO are analysed and two different defect mechanisms are identified as the cause of the non-stoichiometry in CCTO. The first mechanism involves a variation in the Cu content, which explains the large differences in the intrinsic bulk and extrinsic grain boundary (GB) resistance, and the formation of the ceramic internal barrier layer capacitor (IBLC) structure. The second mechanism is associated with Ca–Cu anti-site disorder causing an unusually high intrinsic bulk permittivity above that predicted from Clausius–Mossotti calculations.


Item Type:Article
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© The Royal Society of Chemistry. The authors acknowledge funding from the European Union under the NUOTO project and grant agreement no. 226716 (FP7/2007-2013). DCS thanks the EPSRC (UK) for funding (EP/ G005001/11). RS acknowledges a Ramón y Cajal fellowship from the MINECO (Spain).

Uncontrolled Keywords:Giant dielectric-constant; Barrier layer capacitor; Effective ionic-radii; Copper-titanate; Oxide; Perovskites; Conduction; Fluorides.
Subjects:Sciences > Physics > Electricity
Sciences > Physics > Electronics
ID Code:32542
Deposited On:28 Jul 2015 09:55
Last Modified:10 Dec 2018 14:58

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