Scientists Explain Limitations of High Temperature Superconductors in High Currents

Since their discovery in late 1980s, superconductors were thought to revolutionize everything that had an electric current flowing, but allowing it to pass through more easily, and with much less heat produced. Ultra-efficient magnetic trains had been envisioned, then, but still haven’t been invented, because high-temperature ceramic superconductor have an issue with big currents.

Peter Hirschfeld, a professor of physics at the University of Florida, helped by five other colleagues, released a paper in which he explains why the atomic-level structural elements of high-temperature ceramic superconductors impede high currents. 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.

Ceramic superconductors are made of rows of atoms arranged slightly askew to each other, with an imperfect vertical and horizontal alignments. Areas of electrical charge build up at the angles where the lines formed by the atoms meet, and act like dams, counteracting with the electronic flow.

The mathematical model Hirschfeld and his colleagues built fits these observations “very nicely”. “We abstracted a very theoretical model of a single boundary” that can be applied to all such boundaries, he said.

The hope of circulating high currents through superconductors is not lost, though, and is far from being a pipe dream. Hirschfeld says that his theory will give a better insight to experimental scientists, who could, over time, develop high temperature superconductors with more permissive grain boundaries.