When Nobel dreams are too hot to handle

日期:2018-02-09 07:35:09 作者:茹瘪 阅读:

By Duncan Graham-Rowe ANYONE who discovers a superconductor that works at room temperature may be handing the world a poisoned chalice. Its discoverer would qualify for a Nobel prize, but a British superconductivity researcher suggests that the material might be too toxic to be usable. Peter Edwards of the University of Birmingham has plotted data on the toxicity of top high-temperature superconductors against the maximum temperatures at which they work. He found a strong correlation between the two (see Figure). Extrapolating to a hypothetical superconductor that keeps its zero resistance up to room temperature results in a compound that is 10 times as toxic as cyanide. The LD50 for this compound—the dose that would kill half of a group of lab rodents—is just 0.4 milligrams per kilogram of body weight. “If this extrapolation is true, there’s no question that these materials would be dangerous to handle,” says Edwards. “Are we going to find ourselves with a superconductor which it is not possible to utilise?” He hopes not. Materials scientists working for IBM in Zürich have provided a ray of hope. They increased the temperature at which one superconductor conducts electricity with zero resistance by squeezing its atoms closer together (This Week, 1 August, p 4). This technique might allow scientists to boost the top temperature for superconductivity while minimising toxicity. But Edwards’s main hope is a recently discovered class of compounds called carbocuprate superconductors, which unlike most high-temperature superconductors do not contain heavy metals such as thallium or mercury. The toxicity of carbocuprates doesn’t seem to correlate with their maximum working temperature. Unfortunately,