Abstract: Oxide materials of (L.sub.x A.sub.1-x).sub.i MO.sub.y, (L.sub.x A.sub.1-x).sub.i M.sub.1-z Cu.sub.z O.sub.y and (L.sub.x A.sub.1-x).sub.i MO.sub.j-.delta. G.sub.k, wherein L is Sc, Y, lanthanides, etc.; A is Ba, Sr. Ca, etc.; M is V, Nb, Ta, T, Zr or Hf; 0<x<1; 0<z<1; i=1, 3/2 or 2; 0<y.ltoreq.4; Gis F, Cl or N; .delta. is oxygen defect, and having a perovskite-like crystal structure, show superconductivity at a temperature higher than the liquid nitrogen temperature.

Abstract: Disclosed is an oxide superconductor, wherein at least the surface layer has a chemical composition represented by the following formula:La.sub.x Sr.sub.y NbO.sub.zwherein0<x<1,0<y<1, and1<z<4,and has a critical temperature (Tc) higher than 100.degree. K.This superconducotr has a high critical temperature and is rendered superconducting by cooling with cheap liquefied nitrogen.This superconductor is prepared by a process comprising carrying out sputtering in an argon atmosphere by using one of NB and an La--Sr--Cu--O oxide as the substrate and the other as the target under such a temperature condition that substitution of Cu by Nb is caused, an quencing the formed film.

Abstract: A superconductive material with a superconducting critical temperature of at least 77.degree. K. comprising 20 at. % Nb, 10 at. % Si, 10 at. % Al and 60 at. % O is provided by simultaneous vapor-phase physical deposition or sputtering of Nb, Si and Al onto a heated sapphire substrate under oxygen-containing atmosphere, followed by a rapid quenching or post-oxidization of Nb-Si-Al ternary system composition having an Nb/Si/Al atomic ratio of 2/1/1. The high critical temperature allows abundantly existing, cheap available liquid nitrogen to be used as a cryogen for developing superconductivity.

Abstract: Oxide materials having the formulae (L.sub.x A.sub.1-x).sub.i MO.sub.y, (L.sub.x A.sub.1-x).sub.i -M.sub.1-z Cu.sub.z O.sub.y and (L.sub.x A.sub.1-x).sub.i MO.sub.j-.delta. G.sub.k, wherein L is Sc, Y, lanthanides, etc.; A is Ba, Sr, Ca, etc.; M is V, Nb, Ta, Ti, Zr or Hf; 0<x<1; 0<z<1; i=1, 3/2 or 2; 0<y.ltoreq.4; G is F, Cl or N; .delta. is oxygen defect, and having a perovskite-like crystal structure, show superconductivity at a temperature higher than the liquid nitrogen temperature these oxide materials can be produced by a substitution diffusion reaction between a substrate and a film or layer deposited on the substrate.