Peculiarities of the stability of superheated superconducting grains near Tc

An original method of preparation and sorting out of micron-size tin grains has been elaborated, which makes it possible to prepare colloids with identical by size spherical grains. Just for such colloids the peculiarities of micron-size tin grainsʹ superheated superconducting state stability near Tc has been registered. The observed behavior of the superheated stateʹs stability is apparently a sort of size effect and may be linked with the change of the nature of the phase transition at temperatures near Tc, at which the penetration depth λ and the coherence length ξ become comparable with the grain size. A quantitative method for determination of the penetration depth at zero temperature λ0 of grained superconducting systems has also been developed.