Si Sr Research Articles

Electron spectroscopy study of Si/Bi 2Sr 2CaCu 2O 8+x(001) interface formation

The process of interface formation during Si deposition onto the surface of singlecrystalline Bi 2Sr 2CaCu 2O 2+x has been investigated. Its reactive character manifesting in appearance of the complicated oxide phase SiSrO has been shown. It is formed as a result of displacing of Bi atoms from the upper crystal layer into the bulk by deposited Si atoms, their interaction with SrO layer and partial oxygen withdrawal from CuO 2 layers. The pure Si phase grows on the intermediate oxide layer in form of islands. The process can be prevented by electron bombardment under low rates of silicon deposition. Electron irradiation of the formed structure with silicon film drives to electron-stimulated dissolution of Si layers in the substrate.

The trace and major element composition of the leaves of some deciduous trees

The contents of 21 trace and major constitutents in the leaves or leaf blades of three species of deciduous trees, sycamore, horse-chestnut and beech, have been studied at regular intervals throughout the season. The various elements can be grouped into three categories: (A) Co, Ni, Fe, V, Ti, Cr, Pb and Al, (B) Mn, B, Si, Ca, Sr, Ba, and Mg, and (C) Cu, Mo, Zn, P, K, and Na. The Group-A elements, including most of those whose essentiality has not been established, together with Fe, show a fall in concentration in the leaf early in the season, probably as a result of dilution due to increase in dry weight as the absolute amount per leaf rises slightly, followed by steady rise until senescence, when a further fall occurs. In Group B, in which Si Sr, and Ba are considered non-essential, there is a continual rise both in concentration and absolute content until late in the season. In Group C, all the elements of which, except possibly Na, are essential, there is generally a gradual fall followed by a period when the content remains relatively constant, although Na and Zn, together with Pb from Group A, show an unexpected increase at senescence.