Strontium temperature

Breohignao C, Cahuzao P, Kebaili N and Leygnier J 1998 Temperature effeots in the Coulombio fission of strontium olusters Phys. Rev. Lett. 81 4612... 

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. 

Magnesium reacts slowly at lower temperatures to give the amide, as do all active metals this reaction is catalyzed by transition metal ions. Aluminum nitride [24304-00-5] AIN, barium nitride [12047-79-9] Ba2N2, calcium nitride [12013-82-0] Ca2N2, strontium nitride [12033-82-8], Sr2N2, and titanium nitride [25583-20-4], TiN, may be formed by heating the corresponding amides. 

Strontium carbonate is a colorless or white crystalline soHd having a rhombic stmcture below 926°C and a hexagonal stmcture above this temperature. It has a specific gravity of 3.70, a melting point of 1497°C at 6 MPa (60 atm), and it decomposes to the oxide on heating at 1340°C. It is insoluble in water but reacts with acids, and is soluble in solutions of ammonium salts. 

Strontium hydroxide, Sr(OH)2, resembles slaked lime but is more soluble in water (21.83 g per 100 g of water at 100°C). It is a white dehquescent sohd with a specific gravity of 3.62 and a melting point of 375°C. Strontium soaps are made by combining strontium hydroxide with soap stocks, eg, lard, tallow, or peanut oil. The strontium soaps are used to make strontium greases, which are lubricants that adhere to metallic surfaces at high loads and are water-resistant, chemically and physically stable, and resistant to thermal breakdown over a wide temperature range (11). 

At room temperature, sulfur unites readily with copper, silver, and mercury and vigorously with sodium, potassium, calcium, strontium, and barium to form sulfides. Iron, chromium, tungsten, nickel, and cobalt react much less readily. In a finely divided state, zinc, tin, iron, and aluminum react with sulfur on heating (19). 

Other. Insoluble alkaline-earth metal and heavy metal stannates are prepared by the metathetic reaction of a soluble salt of the metal with a soluble alkah—metal stannate. They are used as additives to ceramic dielectric bodies (32). The use of bismuth stannate [12777-45-6] Bi2(Sn02)3 5H20, with barium titanate produces a ceramic capacitor body of uniform dielectric constant over a substantial temperature range (33). Ceramic and dielectric properties of individual stannates are given in Reference 34. Other typical commercially available stannates are barium stannate [12009-18-6] BaSnO calcium stannate [12013 6-6] CaSnO magnesium stannate [12032-29-0], MgSnO and strontium stannate [12143-34-9], SrSnO. ... 

Calcium metal was produced in 1855 by electrolysis of a mixture of calcium, strontium, and ammonium chlorides, but the product was highly contaminated with chlorides (1). By 1904 fairly large quantities of calcium were obtained by the electrolysis of molten calcium chloride held at a temperature above the melting point of the salt but below the melting point of calcium metal. An iron cathode just touched the surface of the bath and was raised slowly as the relatively chloride-free calcium solidified on the end. This process became the basis for commercial production of calcium metal until World War II. 

Historically, materials based on doped barium titanate were used to achieve dielectric constants as high as 2,000 to 10,000. The high dielectric constants result from ionic polarization and the stress enhancement of k associated with the fine-grain size of the material. The specific dielectric properties are obtained through compositional modifications, ie, the inclusion of various additives at different doping levels. For example, additions of strontium titanate to barium titanate shift the Curie point, the temperature at which the ferroelectric to paraelectric phase transition occurs and the maximum dielectric constant is typically observed, to lower temperature as shown in Figure 1 (2). 

The chemical identities of the fission products determine their subsequent redistribution, those elements which are in the gaseous state at the temperature of the operation migrating to the cooler exterior of the fuel rods, and die less voltile elements undergoing incorporation in the fuel rod in solid solution. Thus caesium and iodine migrate to the gas fill which sunounds the fuel rod, and elements such as the rare earths and zirconium are accommodated in solid solution in UO2 without significant migration along the fuel rod radius. Strontium and barium oxidize to form separate islands which can be seen under the microscope. 

Both carbonates decompose to their oxides with the evolution of carbon dioxide. The decomposition temperature for calcium carbonate is in the temperature range 650-850 °C, whilst strontium carbonate decomposes between 950 and 1150°C. Hence the amount of calcium and strontium present in a mixture may be calculated from the weight losses due to the evolution of carbon dioxide at the lower and higher temperature ranges respectively. This method could be extended to the analysis of a three-component mixture, as barium carbonate is reported to decompose at an even higher temperature ( 1300 °C) than strontium carbonate. 

Slag modifiers raise the fusion point or sintering temperature of the ash and directly neutralize any S03 formed. They are based on alkaline-earth metals such as magnesium, calcium, and strontium, or rare-earth metals such as cerium they are available as oxides, salts, or soaps. 

A long time passed between the first discovery of AE3(BN2)2 phases [17] (AE = Ca, Sr) and their structural characterizations [18, 19]. Two distinct phases are known to exist for both calcium and strontium nitridoborate, denoted as low-temperature y9-AE3(BN2)2 and high-temperature a-AE3(BN2)2 [20]. Their phase transitions have been studied by temperature-dependent XRD, thermo-... 

The low-temperature (/1-)AE3(BN2)2 phases exhibit two distinct structures for AE = Ca and Sr that can be derived from the cation disordering in their respective high-temperature phases. For / -Ca3(BN2)2 an orthorhombic (Cmca) superstructure of the cubic cell with fi-a bo a, Cq ly l a was obtained, in which the former 8f sites are occupied by seven calcium ions in an ordered fashion. In contrast, the structure of / -Sr3(BN2)2 is simply the result of a transition from a cubic body-centered (Im3m) into a primitive structure (Pm3m), in which the former 2 a position (0, 0, 0 1/2, 1/2, 1/2) is split into two independent positions, of which only one is occupied by strontium (Fig. 8.6). 

Among the high-temperature superconductors one finds various cuprates (i.e., ternary oxides of copper and barium) having a layered structure of the perovskite type, as well as more complicated oxides on the basis of copper oxide which also include oxides of yttrium, calcium, strontium, bismuth, thallium, and/or other metals. Today, all these oxide systems are studied closely by a variety of specialists, including physicists, chemists, physical chemists, and theoreticians attempting to elucidate the essence of this phenomenon. Studies of electrochemical aspects contribute markedly to progress in HTSCs. 

Figure 1.49. Change of the strontium content and Sr/ Sr ratio of Kuroko anhydrite during the deposition and dissolution due to the mixing of hot ascending solution and cold solution (normal seawater) (Shikazono et al., 1983). R mixing ratio (in weight) = S.W./(S.W.+H.S.) in which S.W. and H.S. are seawater and hydrothermal solution, respectively. Open triangle Fukazawa deposits. Solid triangle Hanawa deposits. Open square Wanibuchi deposits. Solid square Shakanai deposits. Concentration of Ca, Sr " " and SO of H.S. are assumed to be 1,(XX) ppm, 1 ppm, and 10 mol/kg H2O, respectively. Concentrations of Ca, Sr " and SO of S.W. are taken to be 412 ppm, 8 ppm, and 2,712 ppm. Temperatures of H.S. and S.W. are assumed to be 350°C and 5°C (Shikazono et al., 1983).

Calcium, strontium and barium azides are not shock-sensitive, but explode on heating at about 150, 170 and 225 (or 152)°C, respectively. In sealed tubes, the explosion temperatures are higher [1], Although calcium azide is rather mildly endothermic (AH°f (s) +46 kJ/mol, 0.37 kJ/g), it can decompose much more exothermally to the nitride (189.9 kJ/mol, 1.53 kJ/g) than to the elements [2],... 

Monorubidium acetylide ignites in molten sulfur barium carbide ignites in sulfur vapour at 150°C and incandesces while calcium, strontium, barium and uranium carbides need a temperature around 500°C to ignite. 

Metal acetylides incandesce on heating in selenium vapour barium acetylide at 150°C, calcium acetylide and strontium acetylide at 500°C and thorium carbide at an unstated temperature. 

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