Washington

Coveted prize: polarized light micrograph of a YBCO high-temperature superconductor. Credit: SHEFFIELD UNIV / SPL

Bell Laboratories, the research arm of New Jersey-based Lucent Technologies, has won a fierce competition for the US patent rights to yttrium barium copper oxide (YBCO). One of the most important high-temperature superconductor materials, this was identified by several rival groups of researchers in early 1987.

After twelve years of deliberation, a panel of four patent judges has ruled that Bell Labs can exercise the patents it filed on 3 March 1987, when at least four research groups in the United States were racing to discover oxide materials that would attain superconductivity at relatively high temperatures.

The race had been set off the previous year when Alex Müller and Georg Bednorz, two researchers at IBM research laboratories at Rüschlikon, Switzerland, discovered a copper oxide ceramic that could conduct electricity without resistance at a temperature of 35 Kelvin. Researchers then urgently looked for ceramics that would show the same property at more than 77 Kelvin — the temperature of liquid nitrogen, a cheap coolant that would allow widespread application of the materials.

Teams at IBM, the Naval Research Laboratory and the University of Houston filed patents for the successful compound soon after Bell Labs, which was then part of AT&T. Under US patent law, they were able to pursue an ‘interference’ procedure to establish which team had actually discovered the compound first, and was therefore entitled to patent it.

The finding of the US Patent and Trademark Office has not yet been publicly announced, but has been welcomed by scientists at Bell Labs. “The process has shown that we were the first to do it,” says Bertram Batlogg, one of the team that made the discovery.

But some of their rivals continue to dispute that, claiming that Bell's rivals were merely unable to prove that they had made the discovery ahead of the filing date. “It was a tie, but they got the patent because they filed first,” says one ex-IBM scientist who has followed the dispute closely.

The scientist also contends that the Bell Labs team “had no data” to prove that it actually had a material that was superconducting above 70 Kelvin throughout 90 per cent of its volume — the criterion the patent office said was needed to prove the value of the discovery. He contends that Bell's X-ray diffraction data, showing the crystalline structure of their material, were insufficient to prove 90 per cent bulk superconductivity.

Batlogg dismisses the distinction. “There's been a misunderstanding about us not having the data,” he says. “The X-ray diffraction data showed that we had a single crystal phase, and the magnetic and transport data showed that we had a superconductor. I'm surprised people are still so worked up about this.”

Lucent has asked BTG, the UK-based technology licensing company, to sell licensing rights to other parties. One such agreement has already been reached with American Superconductor, a corporation based in Westborough, Massachusetts. Patents have also been issued to Bell Labs for YBCO superconductors in Europe since 1996, and in Japan earlier this year, but IBM also has patents in these countries for technology used to fabricate the materials.

It is not clear if IBM will appeal against the patent office's ruling.