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- ItemMeasuring conditions for second order X-ray Bragg-spectrometry(Bristol : Institute of Physics Publishing, 2014) Dellith, J.; Scheffel, A.; Wendt, M.The KL2,3 (α)1,2-lines of 19K, the L3M4,5 (α)1,2-lines of 48Cd, and the M5N6,7 (α)1,2-lines of 92U are lines of comparable energy in the region of approximately 3 keV. In none of these cases were we able to resolve the three doublets when recording the spectra in first order Bragg spectrometry using a PET crystal as the dispersing element. For the purpose of enhancing the resolving power of the spectrometer, the three α spectra were recorded in second order reflection, thereby transferring the lines into another spectral region dominated by X-ray quanta of half the energy. In order to achieve high net peak intensities as well as a high peak-to-background ratio and, consequently, a high level of detection capability, the discriminator settings should be optimized quite carefully. In this manner, we were able to resolve the three α doublets and estimate α2/α1 intensity ratios. Inexplicably, current monographs, e.g., by Goldstein et al, do not contain any indications about the rational use of high order spectrometry. Only a few rather old monographs contain some hints in this regard.
- ItemSuperconductivity in multi-phase Mg-B-O compounds(Amsterdam [u.a.] : Elsevier, 2012) Prikhna, T.; Gawalek, W.; Eisterer, M.; Weber, H.W.; Noudem, J.; Sokolovsky, V.; Chaud, X.; Moshchil, V.; Karpets, M.; Kovylaev, V.; Borimskiy, A.; Tkach, V.; Kozyrev, A.; Kuznietsov, R.; Dellith, J.; Shmidt, C.; Basyuk, T.; Litzkendorf, D.; Karau, F.; Dittrich, U.; Tomsic, M.Structures of MgB2-based materials manufactured under pressure (up to 2 GPa) by different methods having high superconducting performance and connectivity are multiphase and contain different Mg-B-O compounds. Some oxygen can be incorporated into MgB2 and boron into MgO structures, MgBx (X=4-20) inclusions contain practically no oxygen. Regulating manufacturing temperature, pressure, introducing additions one can influence oxygen and boron distribution in the materials and thus, affect the formation, amount and sizes of Mg-B-O and MgBx inclusions and changing type of pinning, pinning force and so affect critical current density jc. The boron concentration increase in initial Mg and B mixture allows obtaining sample containing 88.5 wt% of MgB12 with Tc of 37.4 K (estimated magnetically).