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: High T.sub.c superconducting magnetic shields are provided, together with a method of fabricating such shields, wherein the shields exhibit very high critical applied magnetic field values of at least about 50 Gauss at 77 K. In fabrication procedures, a particulate superconducting ceramic oxide (24) (e.g., thallium 2223) is placed within an uniaxial die assembly (10) and subjected to compression while the die is heated via an external heating jacket (26). After formation of a self-sustaining body (24a), the die (10) is additionally heated via the jacket (26). External heating of the die (10) with the superconducting material therein reduces internal stresses within the shield body.

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).