Nb3Sn Films Research Articles

Fast Rotation Technique for the Formation of a Thin-Film Intermetallic Compound on a Cylindrical Metallic Substrate

A technique has been developed that allows a uniform stoichiometric thin-film compound to be formed on the outer surface of a cylindrical substrate by rapidly rotating the substrate about its longitudinal axis so that the thickness of approximately one lattice constant is deposited per revolution. Niobium and tin were vacuum evaporated simultaneously from separate sources, and bulk quality Nb3Sn films were formed over the complete substrate surface. In addition, samples were prepared of alternate layers of Nb3Sn and a second material with sharp delineation between layers. Some of the technology necessary for this method of film preparation is discussed.

A Liquid Helium Cooled Stage for Electron Microscope and Its Application

Two types of liquid helium cooled stage have been developed, one is for use in HU-11 electron microscope and another in the 1MeV electron microscope. In the former model, liquid helium circulates through a thin copper pipe around the specimen holder. In the second model, the liquid helium is kept in a reservoir, and a pair of flexible bellows are used between the reservoir and the specimen holder for a smooth movement of the holder. The temperature in the both models is measured with an Au+Co−Chromel thermo-element attached to the specimen holder. Observation of magnetic effect in a superconducting film is described. In a defocused image of Nb3Sn film the beam deflection was observed due to the magnetic field pushed out of the film below the transition temperature. The inhomogeneity of the mixed state of a niobium film appeared as a zig-zag edge in the defocused image. The relaxation of the magnetic flux frozed in Nb3Sn film was recorded an a 16 mm cinefilm. Debye-Scherrer rings were observed from nitrogen crystallites condensed on specimen films kept at liquid helium temperature for sufficiently long period.

A Liquid Helium Cooled Stage for an Electron Microscope

A liquid helium cooled stage for an electron microscope has been constructed. Liquid helium flows through a thin copper pipe around the specimen holder. The flexible pipe allows the specimen movement for observation. The holder and pipe are enclosed in a shield case which is kept nearly at liquid nitrogen temperature. The specimen temperature is controlled by the flow of helium, and is measured with an Au+Co-chromel thermo-element attached to the stage. The specimen can be exchanged by means of a usual mechanism without breaking the column vacuum. Observation of magnetic effect in a superconducting film is described. In a defocused image of Nb3Sn film we observed the beam deflection due to the magnetic field pushed out of the film below the transition temperature. The inhomogeneity of the mixed state of a niobium film appeared as a zig-zag edge in the defocused image. The relaxation of the magnetic flux frozen in Nb3Sn film was recorded on a 16 mm cine-film.