Abstract
A new composite superconducting material in the form of a cellular structure consisting of large Mg grains surrounded by thin MgB2 layers has been prepared. The superconducting properties of such a cellular structure were found to depend on the thickness of the superconducting layer d s. As d s decreases from ∼30 to 1 μm, the critical temperature decreases by more than 10 K. The derivative of the upper critical field with respect to the temperature (dH c2/dT) near T c increases from ∼0.2 T/K at high d s to ∼0.35 T/K at d s ∼6 μm. The critical current density of the cellular samples calculated for the area of the superconductor section is above 105 A/cm2 (T = 4.2 K and H = 1 T).
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Original Russian Text © V.A. Grinenko, E.P. Krasnoperov, B.P. Mikhailov, 2007, published in Fizika Metallov i Metallovedenie, 2007, Vol. 103, No. 6, pp. 594–598.