Dramatically enhanced non-Ohmic properties and maximum stored energy density in ceramic-metal nanocomposites: CaCu3Ti4O12/Au nanoparticles

Nanoscale Research Letters (Impact Factor: 2.78). 11/2013; 8(1):494. DOI: 10.1186/1556-276X-8-494
Source: PubMed


Non-Ohmic and dielectric properties of a novel CaCu3Ti4O12/Au nanocomposite were investigated. Introduction of 2.5 vol.% Au nanoparticles in CaCu3Ti4O12 ceramics significantly reduced the loss tangent while its dielectric permittivity remained unchanged. The non-Ohmic properties of CaCu3Ti4O12/Au (2.5 vol.%) were dramatically improved. A nonlinear coefficient of [almost equal to] 17.7 and breakdown electric field strength of 1.25 x 104 V/m were observed. The maximum stored energy density was found to be 25.8 kJ/m3, which is higher than that of pure CaCu3Ti4O12 by a factor of 8. Au addition at higher concentrations resulted in degradation of dielectric and non-Ohmic properties, which is described well by percolation theory.

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    ABSTRACT: We observe the large enhancement in the dielectric permittivity near the percolation threshold in a composite nanoparticle system consisting of metallic RuO2 grains embedded into CaCu3Ti4O12 (CCTO) matrix and annealed at 1100 °C. To understand the nature of the dielectric response, we prepared CCTO by using standard solid state and sol-gel processes, with the relative permittivity found to be on the order of 103–104 at 10 kHz. For RuO2/CCTO composites, an increase in the real part of the dielectric permittivity by approximately an order of magnitude is observed in the vicinity of the percolation threshold, with moderate losses at room temperature. The critical exponent of dielectric permittivity and conductivity of these composites are lower than universal value (0.8–1). In these composite systems, both Maxwell-Wagner and percolation effects have been found responsible for the enhancement of dielectric permittivity.
    Applied Physics Letters 08/2014; 105(7):072901-072901-4. DOI:10.1063/1.4893009 · 3.30 Impact Factor

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