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For ceramic coloring. | Atomic Number: | 59 | Atomic Symbol: | Pr | | Atomic Weight: | 140.9077 | Electron Configuration: | 2-8-21-8-2 | | Shells: | 2,8,18,21,8,2 | Filling Orbital: | 4f3 | | Melting Point: | 935oC | Boiling Point: | 3127oC | | Description: | Rare earth metal. | | Uses: | Used for coloring glass and ceramic glazes |
History(Gr. prasios, green, and didymos, twin) In 1841 Mosander
extracted the rare earth didymia from lanthana; in 1879, Lecoq de Boisbaudran
isolated a new earth, samaria, from didymia obtained from the mineral
samarskite. Six years later, in 1885, von Welsbach separated didymia into two
others, praseodymia and neodymia, which gave salts of different colors. As with
other rare earths, compounds of these elements in solution have distinctive
sharp spectral absorption bands or lines, some of which are only a few Angstroms
wide.
OccurenceThe element occurs along with other rare-earth elements in a
variety of minerals. Monazite and bastnasite are the two principal commercial
sources of the rare-earth metals. Ion-exchange and solvent extraction techniques
have led to much easier isolation of the rare earths and the cost has dropped
greatly in the past few years.
Properties- Praseodymium can be prepared by several methods, such as by calcium
reduction of the anhydrous chloride of fluoride.
- Misch metal, used in making cigarette lighters, contains abou 5%
praseodymium metal.
- Praseodymium is soft, silvery, malleable, and ductile.
- It was prepared in relatively pure form in 1931.
- It is somewhat more resistant to corrosion in air than europium, lanthanum,
cerium, or neodymium, but it does develop a green oxide coating that spalls off
when exposed to air.
- As with other rare-earth metals, it should be kept under a light mineral oil
or sealed in plastic.
- The rare-earth oxides, including Pr2O3 are among the most refractory
substances known.
Uses- Along with other rare earths, it is widely used as a core material for
carbon arcs used by the motion picture industry for studio lighting and
projection.
- Salts of praseodymium are used to color glasses and enamels; when mixed with
certain other materials, praseodymium produces an intense and unusually clean
yellow color in glass.
- Didymium glass, of which praseodymium is a component, is a colorant for
welder's goggles.
CostsThe metal (99%+ pure) is priced at about $70/oz.
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