SPECTRUM

Chemical Fact Sheet

Strontium

Chemical Abstract Number (CAS #) 7440-24-6
Analytical Methods 200.7 - 200.8 - 6010 - 6020
Atomic Symbol Sr

Synopsis from the CRC Handbook of Chemistry and Physics 92nd Edition 2011-2013

Strontium (Strontian, town in Scotland), Sr; at. wt. 87.62(1); at. no. 38; m.p. 777 C; b.p. 1382 C; sp. gr. 2.64; valence 2. Isolated by Davey by electrolysis in 1808; however, Adair Crawford in 1790 recognized a new mineral (strontianite) as differing from other barium minerals (baryta). Strontium is found chiefly as celestite (SrSO4) and strontianite (SrCO3). Celestite is found in Mexico, Turkey, Iran, Spain, Algeria, and in the U.K. The U.S. has no active celestite mines. 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 540 C. Strontium is softer than calcium and decomposes water more vigorously. It does not absorb nitrogen below 380 C. It should be kept under mineral oil 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. Thirty-two other unstable isotopes and isomers 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 Auxiliary 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. All color TV and cathode ray tubes sold in the U.S. are required by law to contain strontium in the face plate glass to block X-ray emission. Strontium also improves the brilliance of the glass and the quality of the picture. 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 it is very soft. It does not occur naturally. Strontium metal (99% pure) costs about $220/kg.

Atmosphere

A relatively high concn of strontium in air dust (600 ug/cu m) was reported. Metal fumes generated during welding of steel gave 3 ug strontium/cu m. Metal fumes generated during welding of steel


DISCLAIMER - Please Read






Florida-Spectrum List of Services
Florida-Spectrum Homepage