Abstract: Improved superconducting thin films are provided having very high T.sub.c (zero) and J.sub.c values, on the order of greater than or equal to 120K and 10.sup.5 A/cm.sup.2 or greater, respectively. The films of the invention are adapted for deposit and support on a compatible substrate, and include a superconductive material, most preferably Tl.sub.2 Ba.sub.2 Ca.sub.2 Cu.sub.3 O.sub.10, with up to about 10% elemental gold admixed with the superconductive material. The preferred method for fabricating the thin film superconductors comprises first forming a non-superconducting precursor film on a compatible substrate which is placed in contact with an unsintered bulk body containing thallium; the substrate with precursor film are sintered with the bulk body to form the desired superconductor material.

Abstract: Improved superconducting oxides are provided having the general formula (Hg.sub.1-x Tl.sub.x)Ba.sub.2 Ca.sub.n-1 Cu.sub.n O.sub.2n+2+.alpha. where x is from about 0.05-0.5 and n is 1, 2, 3 or 4, and .alpha. is an oxygen enrichment factor. The Tl-doped oxides exhibit very high T.sub.c and J.sub.c values.

Abstract: Composite bulk superconducting materials having desirable physical, measured transport current density and high T.sub.c superconducting characteristics are provided which comprise a first matrix of superconducting ceramic oxide crystalline grains with a second matrix of elemental metal (gold, silver, palladium and tin) situated within the interstices between the crystalline grains. Preferably, each matrix is a continuous phase within the composite material, with the ceramic oxide preferably being present at a level of at least about 80% by weight, whereas the elemental metal is present at a level of up to about 20% by weight. In fabrication procedures, a precursor superconducting ceramic oxide is first prepared and reduced to a fine powder size; this is mixed with powdered elemental metal, and the mixture is compressed using high compaction pressures on the order of 14 tons/cm.sup.2 or greater to form a body, which is then sintered to yield the composite.

Abstract: An improved technique for the fabrication of thallium-based superconducting oxides, and particularly Tl:Ba:Ca:Cu:O 2223 oxides, is described which allows production of very pure superconductors (>95% 2223 phase) having excellent structural characteristics. The method of the invention involves first forming a self-sustaining body of starting oxides and subjecting this body to a sintering technique wherein the temperature of the body is gradually raised to a maximum level of about 850.degree.-930.degree. C., followed by maintaining the body at this temperature for a period of about 48 hours. The body is then slowly cooled to avoid distortion and loss of superconducting character. Most preferably, the sintering is a two-stage operation, wherein the body is first heated a relatively low rate (e.g., 1.degree.-10.degree. C./min.) to a temperature of about 650.degree.-750.degree. C., followed by faster heating at a higher rate to achieve the maximum sintering temperature.

Abstract: A selectively controllable, direction-, amplitude- and/or frequency-specific superconducting shield (10) is provided which includes a multiply-connected superconducting shield (12) adapted to shield a zone (13) from external magnetic, electric and/or electromagnetic fields and signals. Controlled gating of the shield (12) is provided by means (16) serving to selectively lower the critical shielding current density of a portion (26) of the shield (12) to a level permitting entrance of external fields through the portion (26), while leaving the critical shielding current densities of other portions of the shield (12) at higher, field-shielding levels. The means (16) preferably includes respective, selectively energizable coil pairs (CP.sub.1, CP.sub.2 . . . CP.sub.n) disposed about the shield (12). A highly sensitive magnetic detector (30) would include the shielding device (10) as well as a SQUID assembly (18) situated within the zone (13) defined by shield (12).