AC charging/discharging of de-alloyed Si-Al-V alloy ribbons

In anticipation of prompt ac charging/discharging characteristics, the capacitance of de-alloyed Si_1-x(Al_0.5,V _0.5)_x (x = 0.15, 0.2, 0.3, and 0.4) alloy ribbons with resistivities of 0.01-4300 Ωcm was measured as a function of frequency between 1 mHz and 1 MHz, using exponential transient analysis for electric charging/discharging. The capacitance of de-alloyed Si-7.5 at.%.Al-7.5 at.%. V obtained by prompt (100 ms-25 ns) charging/discharging decreased logarithmically from 105 μF to 18 pF as frequency increased from 1 mHz to 10 kHz, and then saturated between 10 kHz and 1 MHz. From the observed electrode distance dependence on capacitance, we deduced that the alloy consisted of a distributed constant equivalent circuit (series with 1.2% parallel), analogous to electric double layer capacitors.