Tantalum capacitors are a subtype of electrolytic capacitors. They are made of tantalum metal which acts as an anode, covered by a layer of oxide which acts as the dielectric, surrounded by a conductive cathode.The use of tantalum allows for a very thin dielectric layer.antalum capacitor definition. Tantalum capacitors are electrolytic capacitors which use tantalum metal for the anode. They are polarized capacitors with superior frequency and stability characteristics.