After the heady optimism over the prospects for superconducting ceramics, the cold douche of reality as researchers seek ways of taking the phenomena out of the labs and fabricating them into materials that could be used for practical applications. The claim from Georgia Tech that superconductivity was observed in a copper oxide ceramic at 227oC (CI No 823) was one of the few really bullish announcements to be made at the conference held by the US Materials Research Society in Boston, where most of the talk was of how difficult the materials are proving to work. AT&T Bell Laboratories did report progress on one key problem – that the ceramics in general cannot carry enough electricity for practical applications – saying that it had come up with a processing technique that creates a superconducting ceramic that can carry up to 1,000 Amps per square centimetre in a moderately strong magnetic field – one unexpected drawback that has emerged is that the ceramics tend to cease to superconduct when they are subjected to a strong magnetic field. According to the Wall Street Journal, the Bell Labs scientists achieved their success by melting the ceramic and cooling it in a precisely controlled environment that caused partial alignment of the crystals: it seems that the junctions between unaligned crystals have been a major source of poor electrical connections. The researchers believe that they can improve current capacities by a factor of 10 by refining further the melting and cooling technique. But still to be solved is a means of drawing the ceramics into wires that are not so rigid and brittle that they are well-nigh impossible to handle in practical applications. This is assumed to require strengthening them with other materials – but contact with almost any other material apart from silver seems to destroy superconductivity of the wires. Nevertheless, while solving the problems highlighted is crucial to high-voltage applications like power transmission and levitating trains, they are less so for microelectronics.
SUPERCONDUCTIVITY: NOW THE DIFFICULT PART GETS UNDER WAY
