Strontium calcium

Strontianite is the naturally occurring form of strontium carbonate. It has a theoretical strontium oxide content of 70.2%, but no economically workable deposits are known. There are some naturally occurring strontium—barium and strontium—calcium isomorphs, but none has economic importance. 

Tertiary bismuthines appear to have a number of uses in synthetic organic chemistry (32), eg, they promote the formation of 1,1,2-trisubstituted cyclopropanes by the iateraction of electron-deficient olefins and dialkyl dibromomalonates (100). They have also been employed for the preparation of thin films (qv) of superconducting bismuth strontium calcium copper oxide (101), as cocatalysts for the polymerization of alkynes (102), as inhibitors of the flammabihty of epoxy resins (103), and for a number of other industrial purposes. 

In 1817 Dobereiner found that if certain elements were combined with oxygen in binary compounds, a numerical relationship could be discerned among the equivalent weights of these compounds. Thus when oxides of calcium, strontium, and barium were considered, the equivalent weight of strontium oxide was approximately the mean of those of calcium oxide and barium oxide. The three elements in question, strontium, calcium, and barium were said to form a triad. 

Comar, C.E. 1963 Some over-all aspects of strontium-calcium discrimination. In Wasserman, R.H., ed.. The Transfer of Calcium and Strontium Across Biological Membranes. New York, Academic Press 405 18. 

Comar, C.L., Wasserman, R.H. and Nold, M.M. 1956 Strontium-calcium discrimination factors in the rat. Proceedings of the Society for Experimental Biology 92 859-863. 

Ichikawa, R.A.Y.E. 1963 Strontium-calcium discrimination in rats feeding on rice, milk and commercial diets. Health Physics 9 717-720. 

Lough, S., Rivera, J. and Comar, C.L. 1963 Retention of strontium, calcium, and phosphorus in human infants. Proceedings of the Society of Experimental Biological Medicine 112 613-636. 

Graham, D.D., Bender, M.L., Williams, D.F. and Keigwin, L.D. Jr. (1982) Strontium-calcium ratios in Cenozoic planktonic foraminifera. Geochim. Cosmochim. Acta, 46, 1281-1292. 

Uranium mineral first is digested with hot nitric acid. AH uranium and radium compounds dissolve in the acid. The solution is filtered to separate insoluble residues. The acid extract is then treated with sulfate ions to separate radium sulfate, which is co-precipitated with the sulfates of barium, strontium, calcium, and lead. The precipitate is boiled in an aqueous solution of sodium chloride or sodium hydroxide to form water-soluble salts. The solution is filtered and the residue containing radium is washed with boiling water. This residue also contains sulfates of other alkahne earth metals. The sohd sulfate mixture of radium and other alkahne earth metals is fused with sodium carbonate to convert these metals into carbonates. Treatment with hydrochloric acid converts radium and other carbonates into chlorides, all of which are water-soluble. Radium is separated from this solution as its chloride salt by fractional crystallization. Much of the barium, chemically similar to radium, is removed at this stage. Final separation is carried out by treating radium chloride with hydrobromic acid and isolating the bromide by fractional crystallization. 

Davy isolates barium, strontium, calcium, and magnesium. Gay-Lussac and Thenard isolate boron. Davy isolates it independently. 

The exceptional character o fluorine.—Fluorine has a little more individuality, so to speak, than the other three members of the family (1) There are no compounds of oxygen and fluorine (2) Chlorine, bromine, and iodine or the haloid acids show no signs of the remarkable effect of hydrofluoric acid and of fluorine on silicon (3) The solubilities of the sulphates, nitrates, and chlorides of barium, strontium, calcium, and magnesium decrease with increasing at. wt. of the metal, while the solubilities of the hydroxides increase the solubilities of the iodides, bromides, and chlorides... 

Detection and determination.—The periodates behave towards reducing agents like the iodates. They are usually but slightly soluble in water and readily soluble in dil. nitric acid. When soln. of sodium periodate are added to barium, strontium, calcium, lead, and silver salts, precipitates of dimesoperiodates are obtained, and the mother liquor has an acid reaction—the silver salt is pale yellow, the others white—silver iodate is also white. The silver precipitate becomes dark red when boiled in water the fresh precipitate is very soluble in ammonia, the dark red... 

Electroceramics. Titanates like barium, strontium, calcium and lead titanate prepared from finely divided, high-purity TiOz hydrolysates are used in capacitors, PTC-resistors and piezoelectric materials. The specifications of the Ti02 starting materials with respect to purity, reactivity, and sintering properties are expected to become more stringent. The market is estimated to be several thousand of tonnes a year as TiOz. A strong annual growth is expected. 

The temperature also affects the process of coagulation.8 With the chlorides of potassium, sodium, lithium and ammonium the velocity of flocculation varies inversely as the temperature 9 with the chlorides of barium, strontium, calcium, magnesium and cadmium the velocity varies directly as the temperature with aluminium chloride it is independent of the temperature. Heating thus stabilises the sol towards univalent cations but diminishes the stability towards bivalent ions.10 The... 

Research chemists found that they could modify the conducting properties of solids by doping them, a process commonly used to control the properties of semiconductors (see Section 3.13). In 1986, a record-high Ts of 35 K was observed, surprisingly not for a metal, but for a ceramic material (Section 14.24), a lanthanum-copper oxide doped with barium. Then early in 1987, a new record T, of 93 K was set with yttrium-barium-copper and a series of related oxides. In 1988, two more oxide series of bismuth-strontium-calcium-copper and thallium-barium-calcium-copper exhibited transition temperatures of 110 and 125 K, respectively. These temperatures can be reached by cooling the materials with liquid nitrogen, which costs only about 0.20 per liter. Suddenly, superconducting devices became economically viable. 

Smith S.V., Buddemeier R.W., Redaije R.D. and Houck J.E. (1979) Strontium-calcium thermometry in coral skeletons. Science 204, 404-407. 

Thompson T.G. and Chow T.J. (1955) The strontium calcium atom ratio on carbonate-secreting marine organisms. In Papers in Marine Biology and Oceanography, Deep-Sea Res. Suppl., 3,20-39. 

Using the voltaic battery, Davy showed that the alkaline earths, like the caustic alkalis, were compounds containing oxygen and previously unknown metals. His characterization and naming of the alkaline earth metals followed his discovery of them barium, strontium, calcium, and magnesium are the names he invented for these metals. Like the names sodium and potassium, they are still in use today. 

The one-meter-long conductor, based on a bismuth-strontium-calcium-copper oxide superconductor, carries over 2300 amps of direct current at liquid nitrogen temperatures (77 K). This is more than twice the current-carrying capability of conventional copper cables. 

In February of 1988, however, Chu—and researchers working on their own at the National Institute for Metals at Japan s City of Brains, at Tsukuba—came up with something that finally seemed legitimate. The compounds used by the two groups were very similar, mixtures of bismuth—a crystalline metal used to make alloys, heat-activated safety devices for fire detection and sprinkler systems, and medical and cosmetic preparations—strontium, calcium, copper, and oxygen (Chu s also contained aluminum). The Japanese ceramic had zero resistance at 105° K, Chu s at 114° K. 

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