Effect of DC bias on dielectric properties of nanocrystalline CuAlO₂

Abstract

Grain boundary effect on the room temperature dielectric behavior in mechanically alloyed nanocrystalline CuAlO₂ has been investigated using impedance spectroscopy under the applied DC bias voltages 0 V to 4.8 V in a periodic interval of 0.2 V. Analysis of impedance data confirms the existence of double Schottky potential barrier heights (Φ_b) between two adjacent grains (left and right side) with grain boundary and its influences in dielectric relaxation time (τ), dielectric constant (ε′) and dielectric loss (tan δ) factor. Also, clear evidence on the suppression of (Φ_b was demonstrated in the higher applied bias voltages with the parameter τ. At equilibrium state, τ is 0.63 ms and it was reduced to 0.13 ms after the 3.2 V applied DC bias. These observed DC bias voltage effects are obeying ‘brick layer model’ and also elucidates (Φ_b is playing a crucial role in controlling dielectric properties of nanomaterials.