Scientists Heat Up Search for Superconducting Materials
Scientists have made startling discoveries in separate hot and cold experiments that may revolutionize theories about the flow of electrical current in materials known as superconductors.
When cooled to temperatures far below zero, superconductors lose all resistance to electricity, theoretically becoming capable of carrying power for distances greater than ever before imagined and eliminating the need for substations along the way.
The goal of the worldwide race, however, is to find materials that will superconduct at as close to room temperature as possible, since cooling is an expensive and cumbersome process. But in a series of tests, chemists at the Los Alamos National Laboratory are taking another approach.
They have not just supercooled their experiments, they have plunged them into a deep-freeze--355 degrees below zero--to test the role of oxygen isotopes in the flow of electrical current.
Such experiments in ice may determine how superconductors at higher temperatures will allow magnetic levitation trains to float at supersonic speed cushioned only on a magnetic field.
“Our results are likely to change the physics theory on what causes superconductivity,” said a hopeful Kevin Ott, chief chemist in the frosty research at the New Mexico lab.
He and his team substituted oxygen-16, the type comprising most of Earth’s atmosphere, with oxygen-18, which is heavier by virtue of two more neutrons. The scientists stitched the gas into a lattice of metals to test its superconductivity.
Heavier Isotopes
Ott said his below-zero studies reveal that synthesizing materials with heavier isotopes of oxygen causes them to conduct electricity more efficiently.
Though the Los Alamos experiments illustrate what happens during a drop in superconductivity temperature, the isotope exchange will advance the understanding of superconducting materials hot or cold, Ott explained.
He and his team synthesized a material that consisted of metals used in previous superconducting experiments--yttrium, barium and copper interconnected with oxygen-18 atoms to hold it together.
But scientists at the Carnegie Institution in Washington, who are continually turning up the heat on their experiments, are finding that the higher the temperature, the more significant the part played by copper.
Robert Hazen of Carnegie’s geophysical lab said superconductor theory is still in its infancy. But added that scientists generally believe that oxygen-copper layers “are donating electrons to the superconducting process,” somehow, allowing electricity to flow with no resistance.
“If the theorists could tell just exactly what is causing superconductivity, then we could modify the structure of materials to match the theory,” he said.
