An ac magnetization technique was used to study superconductivity in tin loaded nanoporous silica matrices, opal matrix and two porous glasses. The behavior of type-II superconductors with a sharp transition at zero bias field was observed. Regular increase in the superconducting temperature up to 4.2 K and in a critical field up to Hc2(0) ≅ 54 kOe with decreasing pore size was found. A crossover from the upturn to the common downturn curvature in the Hc2(T) line was seen for all nanocomposites; the upturn curvature was more pronounced for the matrix with the finest pores.
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