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|Atomic Number:||38||Atomic Symbol:||Sr|
|Atomic Weight:||87.62||Electron Configuration:||2-8-18-8-2|
|Melting Point:||769oC||Boiling Point:||1384oC|
|Uses:||For nuclear batteries in buoys, flares and fireworks for crimson
History(Strontian, town in Scotland). Isolated by Davey by electrolysis
in 1808; however, Adair Crawford in 1790 recognized a new mineral (strontianite)
as differing from other barium minerals.
SourcesStrontium is found chiefly as celestite and strontianite. The
metal can be prepared by electrolysis of the fused chloride mixed with potassium
chloride, or is made by reducing strontium oxide with aluminum in a vacuum at a
temperature at which strontium distills off.
PropertiesThree allotropic forms of the metal exist, with transition
points at 235 and 540C. Strontium is softer than calcium and decomposes water
more vigorously. It does not absorb nitrogen below 380C. It should be kept under
kerosene to prevent oxidation. Freshly cut strontium has a silvery appearance,
but rapidly turns a yellowish color with the formation of the oxide. The finely
divided metal ignites spontaneously in air. Volatile strontium salts impart a
beautiful crimson color to flames, and these salts are used in pyrotechnics and
in the production of flares.
IsotopesNatural strontium is a mixture of four stable isotopes. Sixteen
other unstable isotopes are known to exist. Of greatest importance is 90Sr with
a half-life of 29 years. It is a product of nuclear fallout and presents a
health problem. This isotope is one of the best long-lived high-energy beta
emitters known, and is used in SNAP (Systems for Nuclear Auxilliary Power)
devices. These devices hold promise for use in space vehicles, remote weather
stations, navigational buoys, etc., where a lighweight, long-lived,
nuclear-electric power source is needed.
UsesThe major use for strontium at present is in producing glass for
color television picture tubes. It has also found use in producing ferrite
magnets and in refining zinc. Strontium titanate is an interesting optical
material as it has an extremely high refractive index and an optical dispersion
greater than that of diamond. It has been used as a gemstone, but is very soft.
It does not occur naturally.
CostStrontium metal (98% pure) in January 1990 cost about $5/oz