New Material Further Increases Superconductor Temperature
A University of Houston chemist on Monday announced the discovery of a new material that conducts electricity without any losses due to resistance at a temperature of 225 degrees Kelvin (minus 58 degrees Fahrenheit).
That temperature is 70 degrees above the previous record of 155 degrees Kelvin announced last week by scientists at Energy Conversion Devices in Troy, Mich.
But Paul C.W. Chu, the Texas researcher who found the newest material, cautioned that he had not yet been able to reproduce the finding. The possibility thus exists that his observation may have been a fluke. Chu was optimistic, however, that the results would eventually be reproduced.
In recent months, he and other scientists have reported seeing evidence for such “high temperature” superconductivity, but the superconductivity has always disappeared when the materials were warmed to room temperature in order to allow researchers to repeat the procedure. In contrast, Chu’s new material remained superconducting for three weeks even though it was warmed to room temperature repeatedly.
Chu’s optimism that researchers eventually will discover materials that are superconducting near room temperature, about 70 degrees Fahrenheit or 294 degrees Kelvin, was shared by many of the 400-plus scientists assembled here for an international meeting on superconductivity convened by the Lawrence Berkeley Laboratory.
Chu’s new material is a ceramic composed of barium, copper, oxygen and an unspecified rare earth metal.
Scientists have been excited about superconductors since February, when Chu reported the discovery of a new material that became superconducting when cooled to temperatures that can be achieved with liquid nitrogen. Because liquid nitrogen is much cheaper than liquid helium, which is required to cool existing superconductors, scientists predict that the new materials will make many potential applications of superconductivity economically feasible.
Such applications include faster, more compact computers, new ways to generate, transmit, and store electrical energy, and smooth-riding magnetically levitated trains.
If superconductivity can be achieved at room temperature or at temperatures that could be reached with mechanical cooling systems similar to those found in home refrigerators, the cost of such applications could be reduced even more.
But attempts to achieve such high temperatures have proved frustrating. A high superconducting temperature was frequently observed when new samples were first cooled down. When the samples were warmed and then cooled down again, the superconductivity was usually no longer present.
Less than 1% of Chu’s new material was superconducting at 225 degrees Kelvin, and he has “no clues” about the proportions of the various components in the material he made. But scientists are convinced that they will eventually find the high-temperature material.
