Gte Laboratories Incorporated

Margaret O'Connor

Scott J Butler

Sophia R Su

A method for producing a superconducting copper oxide based helical resonator coil exhibiting improved quality factor, Q. A copper oxide based superconductor powder is mixed with a binder melt at about 45-65% solids by volume. The binder is an RCOOR' ester wax with R and R' each a long chain hydrocarbon group of at least 6 carbons. The ester wax has a melting point of about 40.degree.-100.degree. C. and a viscosity of about 94-2000 centipoise at its melting point. The binder/powder mixture is extruded and wrapped around a mandrel to form a helical coil. The coil is embedded in a setter powder and heated in an oxidizing atmosphere at up to about 2.degree. C./min to about 450.degree.-650.degree. C., and held for a time sufficient to remove the binder. The coil is then heated in the oxidizing atmosphere at up to about 3.degree. C./min to at least about 920.degree. C., and held at about 920.degree.-990.degree. C. for a time sufficient to achieve a density of at least about 93% of theoretical density. The densified coil is cooled in the oxidizing atmosphere at below about 2.degree. C./min to at or below about 550.degree. C., and annealed at about 450-550.degree. C. in flowing oxygen for a time sufficient to convert the crystal structure of the coil to at least 50 v/o high T.sub.c phase superconducting perovskite crystal. The geometry of the extruded, wrapped helical coil is selected to produce, after subsequent densification, a helical resonator coil about 3-17 mm in inner diameter, of a total length n .lambda./2, wherein n is an integer and .lambda. is the operating wavelength of the helical resonator coil.

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Worcester, MA, United States of America

Margaret O'Connor