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High Permittivity and Dielectric Response of CaCu₃Ti_3.9(Y_0.5Nb_0.5)_0.1O₁₂ Ceramics

Y. Liu, X. Huang

Journal of Ceramic Science and Technology, Vol. 8, No. 2 (2017), pp. 243-248

DOI: 10.4416/JCST2016-00112

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Abstract

CaCu3Ti3.9(Y0.5Nb0.5)0.1O12 (CCTYNO) ceramics were prepared with the conventional solid-state method. Dielectric properties and electric responses at temperatures from - 80 to 200 °C were investigated in the frequency range of 100 – 1 MHz. A body-centered cubic structure was confirmed by means of X-ray diffraction. High dielectric permittivity (∼ 6000) and low dielectric loss (∼ 0.082) were observed at room temperature. Impedance spectroscopy measurements showed the resistance of the grain boundaries is higher by 2 – 3 orders of magnitude than that of the grains, indicating the different microstructure and electric property. The activation energy for the dc conduction process (0.593 eV) is comparable to that for the relaxation process (0.662 eV), implying that strong interfacial polarization at insulating grain boundaries may be responsible for the dielectric response of CCTYNO ceramic. Polyvalent cations (i.e. Cu+, Cu2+, Ti3+ and Ti4+) may cause changes in the conduction of semiconducting grains at high temperature.

Keywords

Dielectric properties, impedance, co-doping, grain boundary, interfacial polarization

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