A New Property of Etched Niobium Wet Electrolytic Capacitors

An etched niobium capacitor has been made which shows about a ten to one change in capacitance from zero bias to the rated voltage. The approximate relation between the capacitance and the bias has been found to obey the following equation C= Co (V + gb)~J2' If we assume the eontaet potential V
b
to be 0.80 volts, and (C/Co)
²
is plotted versus 1/V + V
b
, we obtain a straight line, thus showing that we are dealing with a p-n junction either at the oxide-solution interface or at an interfaee within the oxide layer. The large bias-effect suggests the possibility of the use of such a eomponent in eontrol circuits at low frequencies in a manner similar to a varaetor diode at high frequencies. Additional Key Words (for Information Retrieval)--niobium, electrolytic capacitor, variable capacitor, solid-state variable capacitor.