Relaxor ferroelectric-like high effective permittivity in leaky dielectrics/oxide semiconductors induced by electrode effects: A case study of CuO ceramics

By Ming Li, A. Feteira, Derek C. Sinclair. 2009

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The electrical behavior of copper oxide (CuO) ceramics sintered at 920 °C has been characterized by a combination of fixed, radio frequency (rf) capacitance measurements, and impedance spectroscopy (IS). Fixed rf capacitance measurements on ceramics with sputtered Au electrodes revealed a temperature- and frequency-dependent high effective permittivity of ∼104 in the temperature range of 150–320 K. The response is similar to that observed for relaxor-ferroelectrics, however, the magnitude of the effect can be suppressed by thermal annealing of the ceramics with Au electrodes in air at 300 °C or by changing the work function of the electrode material by using In–Ga as opposed to Au. IS data analysis revealed the ceramics to be electrically heterogeneous semiconductors with a room temperature dc resistivity <104 Ω cm, consisting of semiconducting grains with relative permittivity, er, <10 and slightly more resistive grain boundaries with “effective” permittivity, eeff, of ∼110. Samples with Au electrodes ex...

Subfields: Electronic, Optical and Magnetic Materials, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/49baa4149fbd18b8533a730225623ab56f9e2431