Browsing by Subject "Synthesis procedure"

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    Homogeneity range of ternary 11-type chalcogenides Fe1 + yTe1−xSex
    (Springer, 2017) Koz, C.; Rößler, S.; Wirth, S.; Schwarz, U.
    The 11-type Fe-chalcogenides belong to the family of Fe-based superconductors. In these compounds, the interstitial Fe is known to strongly influence the magnetic and superconducting properties. Here, we present the chemical homogeneity range of ternary compounds Fe1 + yTe1−xSex based on powder x-ray diffraction, energy dispersive x-ray analysis, and magnetization measurements. Our investigations show that the maximum amount of excess Fe in homogeneous Fe1 + yTe1−xSex decreases with increase in Se substitution for Te. Using our synthesis procedure, single-phase Fe1 + yTe1−xSex, with 0.5 ≤ x < 1 could not be formed for any amount of excess Fe. Further, the superconducting volume fraction in the material is found to be strongly suppressed by excess Fe.
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    Low order controller design for systems with time delays
    (2011-12) Gündeş, A. N.; Özbay, Hitay
    Finite-dimensional controller synthesis methods are developed for some classes of linear, time-invariant, single-input single-output, or multi-input multi-output systems, which are subject to time delays. The proposed synthesis procedures give low-order stabilizing controllers that also achieve integral-action so that constant reference inputs are tracked asymptotically with zero steady-state error. © 2011 IEEE.