Hello Jörg,

Tantal is called tantalum in English.

Tantalum capacitors are in fact electrolytic caps as well. The difference is that they use a solid electrolyte, instead of the liquid that is used in aluminium caps (you know, the stuff that smells like rotten fish when things go horribly wrong ;o) ).

Compared to aluminium capacitors, tantalum devices have a larger capacitance to volume ratio, so they will be smaller for a given capacitance and working voltage. They also have a lower ESR, making them more efficient at higher frequencies. This makes them a good choice for bypass/decoupling capacitor.
The downside is of course that they are much more expensive.

Have a great weekend,
Rob.