In our analysis of High-Temperature
Superconductor research published over the past decade, the
work of Dr. Amit Goyal ranks at #1 by total citations and
at #4 by number of papers, based on 138 papers cited a
total of 1,738 times. The majority of his work can be found
in the field of Materials Science in
Essential Science IndicatorsSMfromThomson
Reuters.
Our analysis reflects only a small portion of Dr.
Goyal's research. The
Web of Science® reports that he has
well over 200 papers cited over 5,000 times. He also holds
more than 50 patents.
Dr. Goyal is a UT-Battelle/ORNL Corporate
Fellow1 and a Battelle Distinguished Inventor
at Oak Ridge National Laboratories in Tennessee. He is also a Fellow of
AAAS, APS, ASM, ACERS, WIF, and IOP. He presently serves on the editorial
board of the Journal of Materials Research, Journal of the American
Ceramic Society, and the advisory boards of NASA's NanoTech
Briefs, the Journal of the Korean Institute of Applied
Superconductivity, and the journal Recent Patents on Materials
Science.
Below, ScienceWatch.com talks
with Dr. Goyal about his highly cited
research.
Would you tell us a bit about your
educational background and research experiences?
I received a Ph.D. in Materials Science & Engineering from the
University of Rochester, NY, in 1991, a MS in Mechanical & Aerospace
Engineering from the University of Rochester in 1988, and a Bachelor of
Technology in Metallurgical Engineering from the Indian Institute of
Technology, Kharagpur, India, in 1986.
"I expect to see materials
engineering increase the performance of HTS
wires significantly, while at the same time I
expect the costs for fabricating the wires to
reduce substantially due to process
optimization and economies of
scale."
I am presently a UT-Battelle/ORNL CORPORATE FELLOW and a Battelle
Distinguished Inventor at Oak Ridge National Laboratory. I have worked at
the Oak Ridge National Laboratory since 1991. My broad research
contributions have been in the area of large-area, low-cost,
high-performance "flexible electronic" devices, including superconducting
devices, photovoltaics, etc., as well as in 3D self-assembly of nanodots of
complex materials within another complex material for device applications.
What influenced your focus on
superconductors?
High-temperature superconductors were discovered in 1986 by two IBM
scientists, Bednorz and Müller. They received a Nobel Prize for their
discovery in 1987. Typically, Nobel prizes are given for discoveries many
years after the discovery occurs (10, 20 years later). In this case, the
two IBM scientists received the Nobel Prize just one year after the
discovery because of the immense potential applications of high-temperature
superconductors (the theory or mechanism of high-temperature
superconductors is still unknown). Every newspaper and magazine carried
articles of how these novel materials would change the world we live in!
In 1987, I was completing my master’s at Rochester (I received the
degree formally in a graduation ceremony in 1988) and was actually all set
to go to business school as I had always had a business mindset. However,
after the awarding of the Nobel Prize and after reading many articles in
newspapers and magazines back in 1987 which speculated on how the world we
live in would change due to these materials, I found myself at a unique
place or stage in the development of the HTS field. It could be compared to
the stage when transistors were discovered in 1947, in the developmental
timeline of the field of microelectronics. Of course, we all know that
within a few decades, the world was completely transformed by
microelectronics. So, I decided that I could always get to business school
later and decided to focus my background in Materials Science &
Engineering to enable the development of "practical or useful"
high-temperature superconductors. Ever since then, this has been the
primary focus of my research work!
In the list of the top 20 authors worldwide with
the highest number of papers during this period, you have the highest
number of papers of anyone in the US or outside of Japan. Only three
other people from the US figure in this list and two of them are from
your institution. Can you comment?
There are many co-authored papers between myself and the other two people
from my institution in your list of top 20 authors worldwide with the
highest number of papers. This might explain why three out of the four
people from the US in this list are from the same institution.
One of your most-cited papers in our analysis is
the 2005 Supercond. Sci. Tech. paper, "Irradiation-free,
columnar defects comprised of self-assembled nanodots and nanorods
resulting in strongly enhanced flux-pinning in
YBa2Cu3O7-dfilms." Would you walk our readers through this paper and its
significance to the field?
Based on prior experiments done by others in the early nineties, it was
common knowledge in the HTS field that columnar defects comprised of
amorphous damage tracks are generated by irradiating high-temperature
superconducting single crystals with heavy ions. It was also shown that the
critical current density is dramatically enhanced when the applied magnetic
field is aligned parallel to columnar damage tracks. Hence, for over a
decade, scientists worldwide have sought the means to produce such columnar
defects in HTS materials without the expense and complexity of ionizing
radiation.
In this paper, we demonstrated that long, parallel, columnar defects
similar to those mentioned above can be obtained using a simple process
without using ionizing radiation.
We demonstrated that nearly continuous columnar defects or vortex pins
along the c-axis in YBa2Cu3O7–8
(YBCO), in the form of self-assembled stacks of BaZrO3 (BZO)
nanodots and nanorods can be formed (See Fig. 1). When the applied magnetic
field was aligned parallel to these defects, a massive improvement in
critical current density of the superconductor was obtained. The work
reported in this paper was first presented publically at the US-DOE Annual
Peer Review in July, 2004 in Washington, DC in a talk titled "RABiTS Based
Strategic Research" (view). This was the first report of the formation of
columnar defects in coated conductors without the use of ionizing
radiation.
Shortly thereafter we reported very high critical currents in 3 µm
thick films in a paper published in Science in 2006 (See Fig. 2;
Kang S, et al., "High-performance high-T-c superconducting wires,"
311[5769]: 1911-14, 31 March 2006). This work has now been extended to more
scalable deposition processes such as MOCVD as presented for the first time
at the ORNL-SuperPower CRADA presentation in the US-DOE Annual Peer Review
in July, 2008 in Washington, DC, in a talk titled "ORNL/SuperPower CRADA:
Development of MOCVD-based, IBAD-2G wire"
(refer to).
Researchers worldwide are now finding a range of materials that can be
incorporated in a similar manner into REBCO-type coated conductors to form
such nanoscale columnar defects to obtain massive improvements in the
superconducting properties, especially in high applied magnetic fields. HTS
wires with such defects may eventually enable applications by meeting the
price/performance requirements for large-scale applications of HTS.
Another paper garnering citation attention is the
2000 Applied Physics Letters (APL) article, "Low angle grain
boundary transport in Yba2Cu3O7-delta films." Would you tell us about
this paper, its goals and findings?
Let me discuss this paper together with two additional papers – (1)
"The RABiTS approach: Using rolling-assisted biaxially textured substrates
for high-performance YBCO superconductors" (Goyal A, et al.,
MRS Bulletin 29[8]: 552-61, August 2004) and (2) "Texture
formation and grain boundary networks in rolling assisted biaxially
textured substrates and in epitaxial YBCO films on such substrates" (Goyal
A, et al., Micron 30[5]: 463-78, October 1999).
These three papers discuss the effect of grain boundaries and texture on
superconducting properties of HTS wires. The MRS Bulletin paper
provides a summary of the RABiTS process for making single-crystal-like HTS
wires, which are being scaled-up in manufacturing by companies such as
American Superconductor Corporation and Sumitomo Electric Corporation. The
Micron paper discusses the grain boundary networks present in
RABiTS-based conductors, characterized using the technique of Electron
Backscatter Kikuchi Diffraction. The APL paper discusses the
effect of grain boundary angle and grain boundary networks in RABiTS as
well as the IBAD-type, polycrystalline, biaxially textured HTS wires on the
superconducting performance. This paper pointed out an exponential decrease
of the critical current density occurs when grain boundaries greater than 4
are present.
The area continues to be of great research interest, and significant
advances have recently been made in this area. New results indicate that
different grain boundary types have a different effect on the
superconducting properties. Results in this general area will continue to
guide research towards the development of HTS wires with better
performance.
What sorts of applications are possible for
superconductors—are there any in common use now (or close to
it)?
Many applications are possible for HTS materials. In just the area of
electrical power there are several large-scale application areas such as
underground transmission cables, transformers, generators, and
fault-current limiters. Motors and magnets are some other big application
areas.
In what directions do you see this field going in
the next decade?
I expect to see materials engineering increase the performance of HTS wires
significantly, while at the same time I expect the costs for fabricating
the wires to reduce substantially due to process optimization and economies
of scale. This should eventually enable massive, large-scale applications
of these materials, thereby finally fulfilling the prophecies of the late
1990’s when the fever of HTS materials took the world by storm!
What would you like the "take-away lesson" about
your research to be?
For a given material with certain "intrinsic" physical properties, there is
generally a lot of room for improvement in the materials performance via
optimization of the "extrinsic" properties. Understanding the reasons why a
certain material does perform to a certain level, or understanding what are
the extrinsic factors that limit the performance of a material, is very
important. Once an understanding is obtained, materials engineering can be
effectively used to result in massive improvements in the
performance!
Dr. Amit Goyal
UT-Battelle/ORNL Corporate Fellow
Battelle Distinguished Inventor
Fellow AAAS, APS, ASM, ACERS, WIF, IOP
Oak Ridge National Laboratory
Oak Ridge; TN, USA
1 Corporate Fellow is the highest
recognition and designation for scientists at DOE’s national
laboratories. Corporate fellowships characterize innovation,
dedication, and significance of extraordinary contributions to
research and development. These contributions have been acknowledged
throughout the United States as well as other nations.
^
Goyal A, et al., "Irradiation-free, columnar
defects comprised of self-assembled nanodots and nanorods
resulting in strongly enhanced flux-pinning in
YBa2Cu3O7-delta films," Superconduct. Sci.
Technol. 18(11): 1533-8, November 2005. Source:
Essential Science Indicators from
Thomson
Reuters.