{ syn. }

{ syn. }

{ syn. }

{ syn. }

100 %

{ syn. }

{ syn. }

{ syn. }

{ syn. }



Praseodymium is a chemical element with the element symbol Pr and atomic number 59 in the periodic table it is in the group of lanthanides and also making it one of the metals of the rare earths. From the green color of its compounds is also the name: the Greek word Prasinos means " green ", didymos "double" or " twin".

  • 7.1 oxides
  • 7.2 halides
  • 7.3 Other compounds


1841 Carl Gustav Mosander extracted the rare earth Didym of lanthanum oxide. Per Teodor Cleve in 1874 remarked that it was all about two elements in Didym. In 1879 Lecoq de Boisbaudran samarium isolated from Didym, which he won from the mineral Samarskite. In 1885, Carl Auer von Welsbach, to separate Didym in praseodymium and neodymium, both of which form salts with different colors.


Praseodymium occurs naturally only in chemical compounds associated with other lanthanides, preferably minerals,:

  • Cerit
  • Monazite
  • Bastnäsit
  • Mixed metal containing 3-5% praseodymium.

The world's reserves are estimated at 4 million tonnes.

Extraction and production

As with all lanthanides ores are first concentrated by flotation, subsequently converted into the corresponding halides of the metals and are separated by fractional crystallization, ion exchange or extraction.

The metal is obtained by electrolysis or reduction with calcium.


Physical Properties

Praseodymium is a soft, white silver paramagnetic metal, which is one of the lanthanides, and rare earth metals. There is something in the air corrosion resistant than europium, lanthanum or cerium, but readily forms from a green oxide layer, which peels off in air. At 798 ° C the hexagonal α -Pr converts in the body-centered cubic β -Pr.

Chemical Properties

At high temperatures burns to praseodymium sesquioxide Pr2O3. It reacts with water to form hydrogen to the Praseodymhydroxid (Pr (OH ) 3). Praseodymium occurs in its compounds on three - and tetravalent, the trivalent oxidation state is the more common. Pr ( III ) ions are yellow-green, Pr ( IV) ions colorless. In specific reductive conditions and divalent praseodymium can be realized, for example, in the praseodymium (II, III ) iodide ( Pr2I5 ).


Natural praseodymium consists only of the stable isotope of 141Pr. 38 other radioactive isotopes are known, 143Pr and 142Pr with a half-life of 13.57 days or 19.12 hours are the longest lasting. All other isotopes have half-lives of less than 6 hours, and most of them less than 33 seconds. There are also 6 metastable states, 138mPr (t ½ 2.12 hours ), 142mPr (t ½ 14.6 minutes ) and 134mPr (t ½ 11 minutes) are the most stable.

The isotopes move an atom mass range of 120.955 ( 121Pr ) to 158.955 ( 159Pr ).


  • Praseodymium is used in alloy with magnesium for the production of high strength metal for aircraft engines.
  • Alloys with cobalt and iron are strong permanent magnets.
  • Praseodymium are used to color glass and enamel (for example in green colored headlight glass in lighting ).
  • The compounds also enhance the UV absorption, and used for eye protection in welding glass.



  • Green praseodymium (III ) oxide ( Pr2O3 )
  • Brown - black praseodymium (III, IV ) oxide ( Pr6O11 )
  • Almost black praseodymium (IV ) oxide ( Pro2 ), CAS 12165-01-4


Are known by all oxidation states more halides, for example, praseodymium (III ) fluoride ( PrF3 ), praseodymium (IV ) fluoride ( pRF4 ), praseodymium (III ) chloride ( PrCl3 ), praseodymium (III ) bromide ( PrBr3 ), praseodymium ( III ) iodide ( PRI3 ), praseodymium (II, III ) iodide ( Pr2I5 ). The trivalent halides form various hydrates.

Moreover, it forms a plurality of Fluoridokomplexe such as K2 [ pRF6 ] tetravalent Pr

Other compounds

Binary compounds are, for example, praseodymium (III ) sulfide ( Pr2S3 ) Praseodymnitrid (PRN ) Praseodymphosphid (PRP).

Besides being praseodymium in various salts, such as the hygroscopic praseodymium (III ) nitrate (Pr ( NO3) 3 · xH2O ), the beautifully crystallized praseodymium (III ) sulfate (Pr2 (SO4) 3 · 8 H2O) and other represented.

Praseodymium (III ) chloride heptahydrate