Praseodymium
Name: Praseodymium
Symbol: Pr
Atomic Number: 59
Mass fraction of the earth’s shell: 5,2 ppm
Melting Point: 931 °C
Boiling Point: 3.520 °C
Electrical Conductivity: 1,43 · 106 A·V−1·m−1
Praseodymium is one of the lanthanides in the periodic table.
Name: Praseodymium
Symbol: Pr
Atomic Number: 59
Mass fraction of the earth’s shell: 5,2 ppm
Melting Point: 931 °C
Boiling Point: 3.520 °C
Electrical Conductivity: 1,43 · 106 A·V−1·m−1
Praseodymium is one of the lanthanides in the periodic table.
HISTORY
Carl Freiherr Auer von Welsbach
The discovery of praseodymium coincided with the discovery of neodymium. In 1885, the Austrian Carl Freiherr Auer von Welsbach was able to separate didymium into praseodymium and neodymium. Didym, Greek for “twin”, had already been extracted from cerite in 1840 by Carl Gustav Mosander and so named because of its strong similarity to lanthanum, which is also found in cerite. The twin then became another pair of twins.
Praseodymium – the name is derived from the Greek prásinos (green) and didymos (double) – was named the green twin by von Welsbach because of the green colouring of its crystals and compounds. Neodymium, from neos for “new”, was called a new twin.
CHARACTERISTICS & EXTRACTION
Praseodymium is a soft, white, hammerable paramagnetic metal that is very similar to neodymium. It oxidises very quickly and should therefore be stored in an inert gas or in petroleum. The oxide itself is greenish in colour, which is also the usual commercial form.
Analogous to neodymium, praseodymium is mainly used for the production of permanent magnets.
Praseodymium occurs in the rocks cerite, monazite, and bastnäsite. Like all rare earths, it only occurs in compounds and must be separated in a complex process. Pure praseodymium must be separated from its accompanying lanthanides. To do this, the ore is first enriched and fluorinated. The praseodymium fluoride is separated by means of crystallisation, ion exchange, or extraction. With the help of calcium, it is reduced to metallic praseodymium. The praseodymium is purified by remelting in a vacuum.
