Praseodymium (Pr) Sputtering Targets

Praseodymium is the third member of the lanthanide series. In the periodic table, it appears between the lanthanides cerium to its left and neodymium to its right, and above the actinide protactinium. It is a ductile metal with a hardness comparable to that of silver. Its 59 electrons are arranged in the configuration [Xe]4f36s2; theoretically, all five outer electrons can act as valence electrons, but the use of all five requires extreme conditions and normally, praseodymium only gives up three or sometimes four electrons in its compounds. Praseodymium is the first of the lanthanides to have an electron configuration conforming to the Aufbau principle, which predicts the 4f orbitals to have a lower energy level than the 5d orbitals; this does not hold for lanthanum and cerium, because the sudden contraction of the 4f orbitals does not happen until after lanthanum, and is not strong enough at cerium to avoid occupying the 5d subshell. Nevertheless, solid praseodymium takes on the [Xe]4f25d16s2 configuration, with one electron in the 5d subshell like all the other trivalent lanthanides (all but europium and ytterbium, which are divalent in the metallic state).