Role of doping and CuO segregation in improving the giant permittivity of CaCu3Ti4O12
| Autor: | Vincenzo Massarotti, Marcella Bini, G Chiodelli, MC Mozzatic, Carlo B. Azzoni, Doretta Capsoni |
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| Rok vydání: | 2004 |
| Předmět: |
Permittivity
Materials science Condensed matter physics Dopant Doping Mineralogy Activation energy Dielectric Condensed Matter Physics Electronic Optical and Magnetic Materials Dielectric spectroscopy Inorganic Chemistry Electrical resistivity and conductivity Materials Chemistry Ceramics and Composites Grain boundary Physical and Theoretical Chemistry |
| Zdroj: | Journal of Solid State Chemistry. 177:4494-4500 |
| ISSN: | 0022-4596 |
| DOI: | 10.1016/j.jssc.2004.09.009 |
| Popis: | The dopant role on the electric and dielectric properties of the perovskite-type CaCu3Ti4O12 (CCTO) compound is evidenced. Impedance spectroscopy measurements show that the relevant permittivity value attributed to sintered CCTO is due to grain boundary (g.b.) effects. The g.b. permittivity value of the pure CCTO can be increased of 1–2 orders of magnitude by cation substitution on Ti site and/or segregation of CuO phase, while the bulk permittivity keeps values 90 e r 180 . Bulk and g.b. conductivity contributions are discussed: electrons are responsible for the charge transport and a mean bulk activation energy of 0.07 eV is obtained at room temperature for all the examined samples. The g.b. activation energy ranges between 0.54 and 0.76 eV. Defect models related to the transport properties are proposed, supported by electron paramagnetic resonance measurements. |
| Databáze: | OpenAIRE |
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