depending on the experimental reservoir
temperature. Between 150 and 200 mg of pure Ce (99.9% Alfa
AESAR, Karlsruhe, Germany, and smart-elements, Vienna, Austria)
were weighed into each Ta crucible with an accuracy of 70.1 mg.
The assembled apparatus was brought outside the glove box
securely closed using a glass stopper. It was connected to the
vacuum pump, evacuated and sealed under a dynamic vacuum of
better than 103 mbar.