When high-temperature superconductors（超导体） were first announced in the late 1980s, it was thought that they would lead to ultra-efficient magnetic（磁性的） trains and other paradigm-shifting technologies. That didn't happen. Now, a University of Florida scientist is among a team of physicists¹ to help explain why.

In a paper set to appear Sunday in the online edition of Nature Physics, Peter Hirschfeld, a UF professor of physics, and five other researchers for the first time describe precisely² how the atomic-level structural³ elements of high-temperature ceramic⁴（陶瓷的） superconductors serve to impede⁵（阻碍，妨碍） electrical current. Their explanation for how "grain boundaries" separating rows of atoms within superconductors impede current is the first to fit a phenomenon that has helped keep the superconductors from reaching their vaunted potential – and puzzled experimental physicists for more than two decades.

"Nobody understood why it was such a strong effect, or why the current was so limited by these grain boundaries," Hirschfeld said. "And that is what we have explained in this paper."

High-temperature superconducting ceramic wires are composed of rows of atoms arranged slightly askew⁶（歪斜的） to each other, as though one piece of graph paper had been melded atop another with the horizontal and vertical⁷ lines at less-than-perfect alignment⁸（精确对准） . Lumps of electrical charge build up at the angles where the lines meet, acting⁹ like dams to interrupt the flow of electricity.

Hirschfeld and his colleagues' contribution was to conceive（构思，认为） and construct a mathematical model that fit these observations "very nicely," he said. "We abstracted a very theoretical model of a single boundary" that can be applied¹⁰ to all such boundaries, he said.

Unfortunately the model does not suggest a way to break down the barriers, although Hirschfeld said it will give researchers a better tool to interpret results of past and future experiments. This gives the team hope that their model could, over time, lead to high-temperature superconductors with less restrictive grain boundaries（晶界） . That would be a step toward helping¹¹ the superconductors, which have found limited applications in areas such as powerful research magnets（磁体） , reach their heralded¹²（先驱，通报） potential.