Abstract: The present invention improves the stability among the qualities of the electron tube cathodes in which the barium scandate is dispersed and contained in the alkali earth metal oxide layer provided on the surface of the base metal, by making the shape and average particle size of the barium scandate similar to those of the carbonate used to form the alkali earth metal oxide, and it avoids the deterioration of the electron emission property for a long time, by setting the concentration of the barium scandate in the alkali earth metal oxide layer to zero at the position close to the surface of the base metal.

Abstract: An impregnated cathode comprising a cathode obtained by impregnating pore portions of a refractory porous substrate with an electron emissive material containing Ba and formed thereon a plurality of thin films made of a high melting metal and Sc, or a high melting metal and a Sc oxide, or a high melting metal, Sc and a Sc oxide, or a high melting metal and a compound of Sc, W and O, said thin films having the same composition but different densities can maintain good emission characteristics even after the sealing off step of tube production because the thin films formed on the cathode surface are oxidation-resistant.

Abstract: An impregnated cathode comprising a refractory porous body whose pore parts are impregnated with an electron emissive material including barium and a thin film layer comprising tungsten, scandium and/or an oxide of scandium, deposited on the surface of the refractory porous body, characterized in that the thin film layer contains an oxide of tungsten, and/or an oxide of tungsten and scandium, has a distinguished electron emission property and a long life.

Abstract: The present invention relates to an impregnated cathode produced by attaching at least two layered thin films, the thin films comprising an under layer consisting of a high melting point metal thin film composed of, for example, Os, Ru, Rh, Pd, Ir, Pt, Re, Mo, W, Ta, etc., and an over layer consisting of a high melting point metal layer which contains Sc.sub.2 O.sub.3 and which is placed over the layer, on the surface of the impregnated cathode pellet generated by impregnating a refractory porous base body with electron emissive materials. The invention relates also to an electron tube having this cathode. This cathode maintains a low work functional mono-layer stably for a long period of time on its surface.

Abstract: An impregnated cathode comprising a refractory porous body impregnated with an electron emissive material and having an electron emissive surface, and a thin film disposed on the electron emissive surface and composed of a refractory metal and one of Sc, scandium oxide and a mixture thereof. The thin film containing Sc or scandium oxide is generated on the body in subsequent to impregnation of the electron emissive material into the refractory porous body with the result that a mono-atomic layer composed of Ba, Sc and O is maintained on the electron emissive surface over a long period of use.

Abstract: An impregnated cathode comprises a porous refractory substrate of refractory material such as tungsten containing at least one of scandium oxide particles and oxide particles containing scandium such as (Al, Sc).sub.2 O.sub.3, and an electron emissive material impregnated into pores of the substrate, and has an operating temperature lower by about 300.degree. C. than that of the conventional impregnated cathode containing no scandium oxide particles, or scandium.

Abstract: An impregnated cathode having a complex porous body of one-body construction which is mounted in a metal sleeve and in which a partition layer made of a porous material having a porosity less than 17% is arranged in close contact with an impregnated layer made of a porous material containing an electron emissive material. The aforementioned porous partition layer takes the place of the conventional partition plate of refractory metal. The impregnated cathode according to the present invention can not only have its size reduced without any difficulty but also enjoy a high emission current density with a remarkably small dispersion.

Abstract: An electron tube cathode has a composite suppression layer structure interposed between the base metal and the electron-emitting material to suppress an interface layer formed through the reaction of the base metal with the electron emissive material. The composite layer structure includes a thin layer of Pt or Re and a layer of oxide of Zr and/or Hf. As a result, the formation of the interface layer is prevented so that the useful life of the electron tube cathode is prolonged.

Abstract: An electron tube cathode in such a structure comprising a Ni-W-Zr alloy (W content: 20-28 wt. %) having a grain size of 4-10 .mu.m as a base metal, a 1,000-2,000 A-thick Pt film provided on the surface of the base metal, and an electron emitting material layer consisting of alkaline earth metal oxide provided on the Pt film has less emission lowering and less peeling of the electron emitting material layer, even if placed in a long time service. The electron tube cathode can be produced according to a method comprising (i) a step of annealing a base metal of Ni-W-Zr alloy (W content: 20-28 wt. %) at 1,000.degree.-1,200.degree. C., (ii) a step of providing a 1,000-2,000 A thick Pt film on the surface of the base metal, and (iii) a step of providing an electron emitting material layer consisting of alkaline earth metal oxide on the Pt film.

Abstract: A superconductive element comprising a substrate, at least one face of which is composed of alumina, and a layer of a superconductive compound of the Nb-Al, Nb-Ga, Nb-Al-Ge or Nb-Ga-Al system formed on the alumina face, which exhibits an excellent critical current density in either a low magnetic field or a high magnetic field and simultaneously has a high critical temperature, and in which peeling or cracking is not caused, and a method for preparing such superconductive element comprising the step of vaccum depositing the above-noted superconductive compound on an alumina surface of a substrate.