Superconductivity in amorphous and microcrystalline transition-metal alloys

Results of x−ray diffraction, electrical resistivity, critical magnetic field, and transport measurements for several bulk amorphous and microcrystalline transition−metal superconductors obtained by liquid quenching are presented and discussed. Simple Jc−Hc2−Tc relations are observed for this class of materials. A linear relation between electronic diffusivity and nearest−neighbors distance is derived from critical field measurements. The relationship between the formation of an amorphous phase by rapid cooling from the liquid state, lattice stability, and the characteristics of phase diagrams are discussed.