Helping Out a High-Temperature Superconductor

September 14, 2005

Researchers at the U.S. Department of Energy’s Brookhaven National Laboratory have discovered a way to significantly increase the amount of electric current carried by a high-temperature superconductor, a material that conducts electricity with no resistance. This is an important step in the drive to create superconductor-based electric and power-delivery devices, such as power transmission lines, motors, and generators. The results are explained in the September 12, 2005, online edition of Applied Physics Letters.

“In theory, superconducting materials can conduct an enormous amount of electric current. But when incorporated into actual devices, certain factors tend to limit the current,” said Brookhaven materials scientist Qiang Li, a co-author on the paper. “We studied these factors and found that one, which we call ‘substrate roughness,’ can actually significantly increase the current-carrying capacity.”

The superconducting material studied here consists of the elements yttrium, barium, copper, and oxygen. Dubbed YBCO, it is a member of a class of copper- and oxygen-containing superconductors called “cuprates.” Cuprates are “high-temperature” superconductors because they superconduct at temperatures much “warmer” than conventional superconductors (although still very cold) — for example, -300°F rather than -440°F. This difference, while not huge, is enough to make cuprates more viable for practical applications than materials that must be kept much colder.

In many of these applications, YBCO films are deposited onto a ‘normal’ metal surface (the “substrate”), forming components known as coated conductors. One of the factors widely thought to degrade the performance of coated conductors is the roughness of the metal surface.

To verify this, Li and his colleagues set out to study and measure how the roughness of the substrate affects the current-carrying capacity of YBCO.

The researchers deposited a YBCO layer onto a substrate prepared with two distinct areas: a rough, corrugated region with nanometer sized ridges and grooves, and a smooth region. This configuration allowed the group to directly compare the behavior of the YBCO film on both surface types. They were able to do this using electrical-transport measurement techniques, which track the amount of supercurrent passing through the material, and “magneto-optical” imaging, a technique used to study superconductors by following their magnetic behavior.

“What we found is remarkable and surprising,” said lead author Zuxin Ye, a graduate student under Li’s supervision. “Rather than limiting the current, the nanoscaled corrugated surface produces more than a 30 percent increase in the supercurrent carried by the YBCO films. This suggests that metal substrates with some degree of roughness at the nanoscale might help improve the performance of high-temperature superconductors.”

The work is the result of a collaboration between scientists in Brookhaven Lab’s Materials Science Department, the Condensed Matter Physics group within the Physics Department, and the Lab’s Center for Functional Nanomaterials. It was supported by the Office of Basic Energy Sciences within the U.S. Department of Energy’s Office of Science.

Source: BNL

Explore further: Researchers use new approach to overcome key hurdle for next-generation superconductors

Related Stories

Why Calcium Improves a High-Temperature Superconductor

June 8, 2004

UPTON, NY - Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have found evidence to prove why adding a small amount of calcium to a common high-temperature superconductor significantly increases ...

Pushing the Boundaries of High-Temperature Superconductors

May 26, 2005

A collaboration led by scientists at the U.S. Department of Energy’s Brookhaven National Laboratory has revealed a new mechanism that explains why adding calcium to a high-temperature superconductor increases its current-carrying ...

Researcher modernizes US power grid

March 30, 2010

Although the U.S. electric power industry is one of the greatest engineering marvels of the 20th century, aging technology and an increase in demand create problems for the electricity infrastructure that need to be fixed. ...

Recommended for you

The Swiss army knife of smoke screens

March 18, 2018

Setting off smoke bombs is more than good fun on the Fourth of July. The military uses smoke grenades in dangerous situations to provide cover for people and tanks on the move. But the smoke arms race is on. Increasingly, ...

World's biggest battery in Australia to trump Musk's

March 16, 2018

British billionaire businessman Sanjeev Gupta will built the world's biggest battery in South Australia, officials said Friday, overtaking US star entrepreneur Elon Musk's project in the same state last year.

Plasmons triggered in nanotube quantum wells

March 16, 2018

A novel quantum effect observed in a carbon nanotube film could lead to the development of unique lasers and other optoelectronic devices, according to scientists at Rice University and Tokyo Metropolitan University.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.