Contact:	Bob Nelson						For immediate release
		(212) 854-6580					October 7, 1997
		rjn2@columbia.edu



Columbia-IBM Team Develops Method
To Detect Tiny Quantities of Superconductors


	A team of researchers from Columbia's Lamont-Doherty Earth Observatory 
and IBM have developed a technology that can find tiny quantities of 
superconducting materials in a soup of other products.
	By using a combination of high-technology methods, which they call 
"scanning SQUID petrology," the scientists were able to detect superconducting or 
magnetic materials at concentrations of less than 1 part per million in samples 
weighing a fraction of a microgram, or millionth of a gram.  They were also able 
to show that a widely-used method of synthesizing superconductors is likely to be 
contaminated by chlorine, which had been thought to be inert in this reaction.
	The new technology will help researchers more readily identify and extract 
superconductors, extremely efficient electrical conductors that are expected to 
have wide application in transportation, energy and science once they are 
perfected.  "Scanning SQUID petrology can be applied to other materials science 
problems to identify superconducting compounds at low concentrations in 
complex mixtures," said Bruce Scott, manager for chemistry and materials 
science at IBM, adjunct senior research scientist at Lamont and a member of the 
research team.
	The work, reported in the Sept. 18 issue of the British journal Nature, was 
conducted by scientists from Lamont, Palisades, N.Y., and IBM's T.J. Watson 
Research Center, Yorktown Heights, N.Y.  They included John R. Kirtley, IBM's 
research staff member for superconducting science; David Walker, professor
of earth and environmental science at Columbia; Bai-Hao Chen, associate 
research scientist at Lamont; and Columbia graduate student Yanhui Wang.
	The search for new superconducting materials is now commonly 
conducted under high-temperature, high-pressure conditions.  But the products 
of such synthesis often are present in a complex mixture of materials in which 
the superconductors may be a tiny fraction.  Small amounts of superconductor 
are easily missed by traditional detection methods.
	Scientists used scanning SQUID ("superconducting quantum interference 
device") microscopy, in which a barely visible dot of crystal is cooled to near 
absolute zero in the presence of a small magnetic field.  Superconductors show up 
as a reduction in the strength of the magnetic field.  The scanning SQUID 
microscope was invented at IBM; the one used in the present work is one of only 
about a half-dozen in existence.
	After using SQUID techniques to find the superconductors, the research 
team applied techniques of petrology - the branch of geology dealing with the 
composition, structure and classification of rocks - to identify the materials.  
Among those techniques are optical microscopy and electron microprobe 
analysis, in which the sample is bombarded with an electron beam.  The elements 
present then emit x-rays at characteristic wavelengths and can be identified.
	The material isolated by the research team was strontium-copper oxide-
chloride.  It was obtained from a reaction of strontium and copper oxides that had 
been thought to yield superconductors, but often produced erratic results.  The 
reason, the team found, is that the potassium chlorate used to add oxygen to the 
experiment also contaminates the process with chlorine.  That conclusion could
not have been arrived at without the new method, the researchers said.
	The work was supported by the National Science Foundation and the 
Electric Power Institute.  Lamont-Doherty Earth Observatory is a part of the
 Columbia Earth Institute, launched in January of this year to promote wise 
stewardship of our planet.

This document is available at http://www.columbia.edu/cu/pr/.  Working press may receive 
science and technology press releases via e-mail by sending a message to rjn2@columbia.edu.

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