AN AC-IMPEDANCE STUDY OF DENDRITIC SILVER 3-DIMENSIONAL ELECTRODEPOSITS

The ac impedance behaviour of electrochemically grown dendritic Ag thr ee-dimensional electrodeposits grown from aqueous Ag+ ion containing s olutions has been studied in the blocking regime covering the 1 less-t han-or-equal-to f less-than-or-equal-to 10(4) Hz frequency range (omeg a = 2pif). These deposits exhibit fractal surface and non fractal mass (volume) characteristics. Impedance data displayed as log Z'' vs. log omega plots show two linear portions with different frequency dispers ion exponents [alpha] = 0.95 +/- 0.03 and [alpha] = 0.67 +/- 0.05, res pectively. The crossover frequency, omega(lambda), as determined from those plots, mainly depends on the electrolyte resistivity and, to a m inor extent, on the Ag+ ion electrodeposition charge. For omega > omeg a(lambda), the surface fractal dimension derived from the reciprocal r elationship, D(s) = (1/alpha) + 1, is D(s) = 2.45 +/- 0.1. This figure agrees with that obtained from the log (area) vs. log (volume) plots.