Strontium transport properties

Recently Bednorz and Muller (1) reported possible superconductivity at 30 K in the metallic-oxide La-Ba-Cu-0 system. Subsequent work by Tanaka and co-workers (2) showed that the high temperature superconductivity is due to the solid solution La BaxCuO. y which forms in the K2NiFA-type structure. Making solid solutions with strontium instead of barium, Cava et. al. (3). were able to show bulk superconductivity at 38 K in La2 xSrxCuOA y. While solid solutions of the type La2.xMxCuOA y (M = Sr, Ba) have been known for some time, (4-5) magnetic and electron transport properties of these compounds had not previously been measured at low temperatures (i.e. <120 K). ... 

The system 8a La Cu Q chosen by Bednorz and Muller (1) for their first investigation of superconductivity was connected to the existence of metallic properties of the oxide BaLa CusOis+s recently isolated in Caen (2). However the method used for the synthesis did not lead to the expected oxide but to a mixture of phases. Fortunately, one of these latter phases was found to be at the origin of superconductivity. In fact the concerned oxide is a M liF -type oxide, La2-xBaxCu04-y, isolated and studied for its electron transport properties several years before in Caen (3-4). It was then shown by several authors (5-9) that the strontium isostructural oxide La2-xSrxCu04-y (10-11) and the calcium compound (3-4) were also superconductors with Tc values ranging form 20K to 40K. 

S( )gaard, M., Hendriksen, P.V., and Morgensen, M. (2007) Oxygen nonstoichiometry and transport properties of strontium substituted lanthanium ferrite. J. Solid State Chem., 180,... 

To be effective, there must be a certain minimum concentration of inhibitor at the interface to be protected. Therefore, there must be sufficient inhibitor in the primer, and these inhibitors need to be soluble enough in water to enable transport of inhibitor to the oxide surface as water permeates the adhesive joint. However, too high of a solubility will rapidly deplete the primer layer of inhibitor resulting in a loss of protection. One of the fortuitous properties of zinc and strontium chromates is the limited solubility of these compounds in water (about 1.2 g/1 at 15°C [33]). 

Calcium. Strontium has chemical properties similar to calcium, but is less efficient than calcium in most biological processes. Calcium and strontium appear to compete for the same transporter elements in the intestine (Bianchi et al. 1999 Blumsohn et al. 1994 Milsom et al. 1987 Reid et al. 1986 Sips et al. 

Inorganic pollutants include (a) cationic heavy metals such as lead, cadmium, and nickel, (b) anionic metals and inorganics such as arsenic, chromium, selenium, nitrate and fluoride, and (c) radionuclides such as strontium and uranium. The geochemistry of these pollutants can widely vary and it depends on the specific pollutant type and soil/sediment properties. The speciation and transport of these pollutants also depend on the dynamic changes in the pH and redox potential of the soil that occurs under applied electric potential. The dominant transport process... 

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