- To the general disbelief of experts in
the field, a University of Buffalo scientist claimed Thursday to have discovered
a material that conducts electricity with "negative resistance"
at room temperature. Such a miraculous material would be a quantum leap
better than long-sought room temperature superconductors, which would only
carry electricity friction-free, without energy loss. A negative resistance
material would actually create electricity. However, most scientists interviewed
said they were highly skeptical of the report by Buffalo's Deborah Chung.
"Negative resistance means you are generating power," said mechanical
engineer Cetin Cetinkaya of Clarkson University in Potsdam, N.Y., who saw
Chung demonstrate her experiment at the International Conference on Composites
Engineering in Las Vegas, where she presented her findings. "Physically,
that's not possible," Cetinkaya said. "I would love to see that.
It would mean when you're working on your laptop, you would be creating
energy." Cetinkaya and others do believe that Chung may have discovered
an "intriguing" new way to change the direction of electric currents,
with possibly useful applications. "This is very similar to the transistor
concept," Cetinkaya said.
'It's Possible They've Made a Little Battery' Although a news release
from the University of Buffalo announced that Chung had discovered a material
that "superconducts at room temperature," she herself stressed
that the material was not superconducting--a unique zero-resistance state
accompanied by peculiar magnetic effects. "We are not claiming that
we've discovered a new superconductor," she said in an interview.
However, she did say that the negative resistance effect could be used
in an electric circuit to "negate positive resistance . . . and the
totality would be zero."
Other scientists said this was not possible. "Negative resistance
violates the second law of thermodynamics," said UCLA physicist Steve
Kivelson. "It's impossible." Caltech material scientist Brendt
Fultz agreed. "It's hard to believe. I'm sure it's violating one of
the two laws of thermodynamics," he said. "It's possible they've
[inadvertently] made a little battery." If so, the "negative
resistance" effect would be temporary, and not useful in applications,
he said. It would certainly not produce zero resistance for any length
of time, he added. Since no peer-reviewed scientific paper was available--only
a four-page abstract--scientists could not adequately evaluate Chung's
claims. She is a widely published expert in the field of "smart"
materials, which can act as sensitive sensors or electrical components
by their very structure, without any added parts like computer chips or
electrical leads. Chung discovered the effect accidentally while testing
a material made of bundles of carbon fibers at high pressure. She placed
two layers of fibers crosswise to each other, and pressed them together
with epoxy. She then attached electrodes to the top and bottom layer, and
passed a small current through. At the point where fibers from the two
layers met, she says, she measured negative resistance. Like water running
over a waterfall, electric currents normally flow only toward one end of
the circuit--that is, "downhill." (Instead of a difference in
height, electric currents are propelled by a difference in voltage.) As
water flows down the hill, it encounters resistance from obstacles like
rocks. Currents similarly run into resistance from atoms as they flow through
wires. Of course, if the bottom of a waterfall were raised higher than
the top, one would expect the water to reverse its flow. The same is true
of a reversal of voltage; current flows in the opposite direction. However,
Chung's measurements show the current switching direction even when the
voltage remained unchanged, as if water suddenly started flowing up a waterfall,
she said. Although Chung said she was not claiming to have created energy,
she did not have a good explanation for the effect. Current flowing in
the wrong direction for any length of time, and without any additional
input of energy, probably violates fundamental laws of nature, scientists
said. Chung theorized that some new mechanism was at work that "overshadowed"
these laws.
Peers Intrigued by Startling Report Several scientists at the meeting
said they were intrigued by Chung's findings. "The electrons are flowing
in the other direction," said materials scientist Jason Lo of the
Canada Center for Minerals and Energy Technology. "That's not usual,
so something has to be happening at the juncture [of the fibers]. The cause
and effect is not known." If the effect is real, said Lo, then it
could be "quite valuable. . . . Whether it is an infinite source of
energy, that is not known yet." Scientists studying zero-resistance
materials have certainly been surprised before. Before 1986, virtually
no physicists believed that superconductivity could exist much above absolute
zero--minus 450 degrees Fahrenheit. The discovery that year of so-called
"high temperature superconductors"--which carry currents friction-free
at temperatures hundreds of degrees higher, though still quite cold--set
off a frenzy of research into new materials. Since then, the discovery
of room temperature superconductivity has been announced many times, but
never confirmed. Discovery of negative resistance, however, would make
the search for room temperature superconductors moot, Kivelson said. Zero
resistance at room temperature would be "trivial" next to negative
resistance, he said. "Who cares about zero when you can do better
than zero?" Several experts in materials research who read Chung's
abstract declined to comment.
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- __________________________
-
- From Richard J. Harvey <rjh1006@multipro.com
-
- ABSTACT
-
- Carbon Fiber Metal-Matrix Composite Superconductor
Sandwich
-
- D.D.L Chung Patent No: 5,059,582 State
Univ of New York at Buffalo ERIP 520
-
- This process involves sandwiching of
a superconducting material between two layers of a carbon fiber metal-matrix
composite. The resulting structure increases tensile and compressive strengths,
resistance to thermal cycling, and increases environmental stability.
-
- Introduction
-
- Current methods for the manufacture of
bulk High-Temperature Superconductors (HTS) result in products which have
very low tensile strength and low compressive strength, thereby lessening
their effectiveness and reliability in applications in power transmission,
coils for magnetic energy storage, magnetic levitation, motors, etc.
-
- Other deficiencies of current production
techniques are the are poor durability after repeated thermal cycling,
which is necessitated by usage at temperatures of 77K or below and instability
in air.
-
- Concept Description
-
- This process involves the sandwiching
of YBa2Cu3O7-ë by two layers of continuous copper-coated carbon fiber
Sn-Pb matrix composite. The resulting structure increases tensile and compressive
strengths, resistance to thermal cycling, and increases stability.
-
- Testing Results
-
- Tensile and compressive strengths of
the sandwich composite were found to be much higher than plain superconductor
strengths due to the effectiveness of load transfer to the composite fibers
and good adhesion of the layers in the sandwich.
-
- Chemical properties were enhanced and
resulted in an increased stability in air for a 15 day period. While the
plain superconductor lost all superconducting properties, the sandwich
structure remained superconducting.
-
- Economic and Market Potential
-
- In microelectronics applications, the
ultimate performance levels of superconductors - high speed, high sensitivity,
high accuracy, and low power consumption are unmatched by devices made
of other materials. Superconducting devices are considered one of the critical
future technologies in defense and commercial applications.
-
- In FY 92, federal procurement of superconductive
devices was $116 M. Applications include devices for electronic packaging,
power transmission, transportation,communications (i.e. satellites) avionics,
motors, and magnetic resonance.
-
- At the 1993 International Superconducting
Summit meeting in Japan, industry experts stated "that while additional
R&D and manufacturing scale-up activities are required to achieve full
commercialization of HTS technology, it is also clear that commercialization
will occur in the near term... Companies that invest aggressively in HTS
technology development will enjoy the benefits of participating in a major
new industrial sector by the turn of the century."
-
- Magnetic Resonance Imaging (MRI) could
be enhanced for ophthalmological applications if resolution and signal-to-noise
ratio (SNR) characteristics could be improved. Current MRI technology
measures matter's response to electromagnetic fields by using radio-frequency
receivers with specialized copper coils. HTS coils could improve the resolution
and SNR of MRI devices.
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- Current Status
-
- The inventor of this process has demonstrated
the benefits of this methodology in a university laboratory environment.
Detailed material property test reports are available on request.
-
- Future Development Needs
-
- The inventor seeks to license this process
to a superconductor manufacturer to incorporate into production capabilities.
-
- This technology has been evaluated and
endorsed by the National Institute of Standards and Technology (NIST) and
its development sponsored in part by the Department of Energy as part
of the Energy-Related Inventions Program.
-
- This information is provided through
the NIST Manufacturing Extension Partnership network, other manufacturing
resources, and directly to selected manufacturers to promote American
economic growth and competitiveness through the deployment of Federally-
sponsored technology.
-
- For Additional Information, contact:
D.D.L. Chung Department of Mechanical & Aerospace Engineering State
University of New York at Buffalo Buffalo, NY 14260-4400 (716) 645-2520
(716) 645-3875 (fax)
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