Method of making a superconducting ceramic body.

摘要

Disclosed is a broadly applicable method for making an article that comprises a superconductive oxide body, including a thin layer on a substrate, or powder particles. In a preferred embodiment, the method comprises forming a precursor melt and contacting at least a part of the melt with oxygen such that the concentration of oxygen in the part of the melt increases to a critical concentration, resulting in formation of the desired oxide, substantially without drop in temperature. The precursor melt comprises at least one metallic element M, and at least the part of the melt is at a temperature T, with Tm < T < To, where Tm is the freezing temperature of the melt and To is the melting temperature of the superconductive oxide. In an exemplary embodiment the melt consists essentially of Yb, Ba, and Cu in 1:2:3 atomic ratio, T is about 900 DEG C. A layer of superconductive oxide on a SrTiO3 substrate is formed by dipping the hot (900 DEG C) substrate into the melt, exposing the melt-coated substrate to oxygen such that oxygenation and solidification of the coating results, and furnace cooling the coated substrate in oxygen. The thus produced coating has composition YbBa2Cu3O9- delta ( delta SIMILAR 2.1), is essentially single phase, strongly textured, has Tc of about 85K and Jc of about 3x10<4> A/cm<2>. An aspect of the invention is the fact that the precursor melt need not be stoichiometric. For instance, we have formed a layer of composition YbBa2Cu3O7 from a melt of composition Yb2BaCu. The ability to practice the inventive method with non-stoichiometric precursor melts makes it possible to produce Y-containing bodies (e.g., YBa2Cu3O7 films on a copper substrate). The inventive technique can produce compositionally essentially homogeneous material. It is readily adaptable ro produce ceramics (including high Tc superconductors) and other materials (e.g., AlN) in a variety of shaped (including wire, tape, and powders) by a variety of techniques (including continuous processing). The inventive method can also be used to form a superconductive bond between two pre-existing ceramic superconductive bodies.