Subject: [Homestead] Nanotech Super Superconductors
Date: Mon, 13 Sep 2004 17:30:33 -0700
Still need to operate at liquid nitrogen temperatures, so not useful in
small-scale devices---still, the Super Superconductor offers large
economy in operation in a large device.
Nanotechnology Leads To Discovery Of Super Superconductors
LOS ALAMOS, N.M., Sept. 9, 2004 -- University of California scientists
working at Los Alamos National Laboratory with a researcher from the
University of Cambridge have demonstrated a simple and industrially
scaleable method for improving the current densities of superconducting
coated conductors in magnetic field environments. The discovery has the
potential to increase the already impressive carrying capacity of
superconducting wires and tapes by as much as 200 to 500 percent in
certain uses, like motors and generators, where high magnetic fields
diminish current densities.
In research reported in the journal Nature Materials, University of
Cambridge scientist Judith Macmanus-Driscoll and her Los Alamos
colleagues discovered that when the compound barium zirconate is
deposited simultaneously with the yttrium-barium-copper-oxide
superconductor it naturally forms nanoscale particles embedded in
superconductor films. The result was a two to five fold increase in the
current densities of coated conductors in high magnetic fields operating
at liquid nitrogen temperatures.
Superconducting wires and tapes carry hundreds of times more electrical
current than conventional copper wires with little or no electrical
resistance. Superconducting technology is poised to bring substantial
energy efficiencies to electrical power transmission systems in the
United States. Much of the excitement caused by this discovery is due to
the fact that the process can be easily and economically incorporated
into commercial processing of the superconductors. The advance is
important for the development of powerful, energy efficient
superconducting electric motors and generators for civilian and military
applications. The Laboratory conducts research and development of
high-temperature superconducting tapes under the auspices of Los Alamos
Superconductivity Technology Center (STC).
Dean Peterson, leader of the STC, said, "This is a significant technical
advancement because it means we are now beginning to understand how to
control defects in these superconducting materials and use them to our
advantage. This was the first time we have been able to control the
structural defects and in doing so, better engineer the material's
structure to optimize performance."
Contrary to what one might think, the presence of certain types of
defects in the superconducting film is not a problem, but a necessity.
Early high temperature superconductivity research had the goal of
eliminating large-scale defects, which effectively blocked the flow of
electrical currents through the material. This required an ordering of
superconducting grains, much like the bricks in a smooth road, allowing
the unimpeded flow of high-density electrical currents. Scientists later
discovered that small, nanoscale defects are required to maintain high
current densities in superconductors, particularly in the presence of
high magnetic fields. Nanoscale refers to defect sizes roughly 50-100
atoms across.
Because magnetic fields create small swirls of current in a
superconductor called vortices, much like tornadoes in the air, that
move through the material under the influence of electrical currents
causing resistance to the flow of the current, the nanoscale defects
immobilize or "pin" the vortices allowing the current to flow without
resistance. These nanoscale defects can come in various forms ranging
from small particles to flat plates and long string-like objects.
Previous attempts to produce dense arrays of these types of small-scale
defects, such as irradiation by fast heavy ions, were impractical for
commercial production or difficult to control in a reproducible manner.
In addition to Macmanus-Driscoll and Peterson, other members of the team
included Stephen Foltyn, Quanxi Jia, Haiyan Wang, Adriana Serquis,
Leonardo Civale, Boris Maiorov, Marilyn Hawley and Martin Maley, all of
Los Alamos. The research was conducted under the auspices of the Los
Alamos Superconductivity Technology Center and was funded by the DOE's
Office of Electric Transmission and Distribution.
###
Los Alamos National Laboratory is operated by the University of
California for the National Nuclear Security Administration (NNSA) of
the U.S. Department of Energy and works in partnership with NNSA's
Sandia and Lawrence Livermore national laboratories to support NNSA in
its mission.
Los Alamos enhances global security by ensuring the safety and
reliability of the U.S. nuclear deterrent, developing technologies to
reduce threats from weapons of mass destruction, and solving problems
related to defense, energy, environment, infrastructure, health and
national security concerns.