Interface impedance in gels with fractally grown copper electrode

Abstract

Fractal growth of copper has been effected in a gel medium of the system CuO-SiO₂ by electrodeposition. The impedance of the cell comprising the fractal copper electrode and the gel has been measured over the frequency range 100 to 2000 kHz. The imaginary part of the impedance shows a ω⁻ⁿ variation with n having values in the range 0.78 to 0.97 for samples in which fractal growth of copper was carried out at different voltages. The contribution to constant-phase-angle (CPA) behaviour is believed to arise due to migration of H⁺ ions. The variation of the exponent n as a function of applied voltage for fractal growth is semi-oscillatory in nature. Le Mehaute's relationship between n and the fractal dimension of electrode d_f is obeyed in the present system.