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For nuclear batteries in buoys.
(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
Strontium 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. Three allotropic forms of the metal exist, with transition points at 235 and 540oC.
Strontium is softer than calcium and decomposes in water more vigorously. It does not
absorb nitrogen below 380oC.
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. Natural 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 lightweight,
long-lived, nuclear-electric power source is needed.
The 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.
Strontium metal (98% pure) in January 1990 cost about $5/oz.
Sources: CRC Handbook of Chemistry
and Physics and the American Chemical Society.