Ryan Stillwell is a materials scientist who conducts research on quantum materials such as superconductors and topological insulators under extreme conditions. He received his PhD from Florida State University in 2013, studying the Fermi surface reconstruction of chromium at high pressure and magnetic fields. He is currently a postdoctoral researcher at Lawrence Livermore National Laboratory, where he investigates actinide and lanthanide systems using high pressure and magnetic field techniques to explore quantum interactions in these materials.
One of my passion is science imagery. Data has become art. I wrote a book based on that idea and have given a presentation based on that book many times.
One of my passion is science imagery. Data has become art. I wrote a book based on that idea and have given a presentation based on that book many times.
Dielectric and Thermal Characterization of Insulating Organic Varnish Used in...Editor IJCATR
In recent days, a lot of attention was being drawn towards the polymer nanocomposites for use in electrical applications due
to encouraging results obtained for their dielectric properties. Polymer nanocomposites were commonly defined as a combination of
polymer matrix and additives that have at least one dimension in the nanometer range scale. Carbon nanotubes were of a special
interest as the possible organic component in such a composite coating. The carbon atoms were arranged in a hexagonal network and
then rolled up to form a seamless cylinder which measures several nanometers across, but can be thousands of nanometers long. There
were many different types, but the two main categories are single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs),
which are made from multiple layers of graphite. Carbon nanotubes were an example of a nanostructure varying in size from 1-100
nanometers (the scale of atoms and molecules). Nano composites were one of the fastest growing fields in nanotechnology. Extensive
literature survey has been done on the nanocomposites, synthesis and preparation of nano filler. The following objectives were set
based on the literature survey and understanding the technology.
Complete study of Organic varnish and CNT
Chemical properties
Electrical properties
Thermal properties
Mechanical properties
Synthesis and characterization of carbon nanotubes
Preparation of polymer nanocomposites
Study of characteristics of the nanocomposite insulation
Dimensioning an insulation system requires exact knowledge of the type, magnitude and duration of the electric stress while
simultaneously considering the ambient conditions. But, on the other hand, properties of the insulating materials in question must also
be known, so that in addition to the proper material, the optimum, e.g. the most economical design of the insulation system must be
chosen.
Perovskites-based Solar Cells: The challenge of material choice for p-i-n per...Akinola Oyedele
Perovskite-based PV have triggered widespread interest in the scientific community because these materials offer the attractive combinations of low cost and theoretically high efficiency. However, several challenges must be overcome for these relatively new PV materials. Among the many important challenges, one is the choice of materials to be used in thin film PV devices..
Based on fundamental principles of solar photovoltaics, this problem focuses on two aspects of the perovskite system:
1) Based on a planar p-i-n device structure, a potential list of p- and n-type charge collecting layers as well as the conductive contacts that could be used with a promising perovskite absorber material was identified, and a proper justification for the selection of each material in the device was given.
2) Three theoretical p-i-n type solar cells were made with the chosen materials and appropriate conductive contacts.
Dielectric and Thermal Characterization of Insulating Organic Varnish Used in...Editor IJCATR
In recent days, a lot of attention was being drawn towards the polymer nanocomposites for use in electrical applications due
to encouraging results obtained for their dielectric properties. Polymer nanocomposites were commonly defined as a combination of
polymer matrix and additives that have at least one dimension in the nanometer range scale. Carbon nanotubes were of a special
interest as the possible organic component in such a composite coating. The carbon atoms were arranged in a hexagonal network and
then rolled up to form a seamless cylinder which measures several nanometers across, but can be thousands of nanometers long. There
were many different types, but the two main categories are single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs),
which are made from multiple layers of graphite. Carbon nanotubes were an example of a nanostructure varying in size from 1-100
nanometers (the scale of atoms and molecules). Nano composites were one of the fastest growing fields in nanotechnology. Extensive
literature survey has been done on the nanocomposites, synthesis and preparation of nano filler. The following objectives were set
based on the literature survey and understanding the technology.
Complete study of Organic varnish and CNT
Chemical properties
Electrical properties
Thermal properties
Mechanical properties
Synthesis and characterization of carbon nanotubes
Preparation of polymer nanocomposites
Study of characteristics of the nanocomposite insulation
Dimensioning an insulation system requires exact knowledge of the type, magnitude and duration of the electric stress while
simultaneously considering the ambient conditions. But, on the other hand, properties of the insulating materials in question must also
be known, so that in addition to the proper material, the optimum, e.g. the most economical design of the insulation system must be
chosen.
Perovskites-based Solar Cells: The challenge of material choice for p-i-n per...Akinola Oyedele
Perovskite-based PV have triggered widespread interest in the scientific community because these materials offer the attractive combinations of low cost and theoretically high efficiency. However, several challenges must be overcome for these relatively new PV materials. Among the many important challenges, one is the choice of materials to be used in thin film PV devices..
Based on fundamental principles of solar photovoltaics, this problem focuses on two aspects of the perovskite system:
1) Based on a planar p-i-n device structure, a potential list of p- and n-type charge collecting layers as well as the conductive contacts that could be used with a promising perovskite absorber material was identified, and a proper justification for the selection of each material in the device was given.
2) Three theoretical p-i-n type solar cells were made with the chosen materials and appropriate conductive contacts.
Formation of diamonds in laser-compressed hydrocarbons at planetary interior ...Sérgio Sacani
The effects of hydrocarbon reactions and diamond precipitation
on the internal structure and evolution of icy giant planets
such as Neptune and Uranus have been discussed for more than
three decades1. Inside these celestial bodies, simple hydrocarbons
such as methane, which are highly abundant in the atmospheres2,
are believed to undergo structural transitions3,4 that
release hydrogen from deeper layers and may lead to compact
stratified cores5–7. Indeed, from the surface towards the core,
the isentropes of Uranus and Neptune intersect a temperature–
pressure regime in which methane first transforms into a
mixture of hydrocarbon polymers8, whereas, in deeper layers, a
phase separation into diamond and hydrogen may be possible.
Here we show experimental evidence for this phase separation
process obtained by in situ X-ray diffraction from polystyrene
(C8H8)n samples dynamically compressed to conditions around
150 GPa and 5,000 K; these conditions resemble the environment
around 10,000 km below the surfaces of Neptune and
Uranus9. Our findings demonstrate the necessity of high pressures
for initiating carbon–hydrogen separation3 and imply
that diamond precipitation may require pressures about ten
times as high as previously indicated by static compression
experiments4,8,10. Our results will inform mass–radius relationships
of carbon-bearing exoplanets11, provide constraints for
their internal layer structure and improve evolutionary models
of Uranus and Neptune, in which carbon–hydrogen separation
could influence the convective heat transport7.
Dr. Ali Sayir presents an overview of his program, Aerospace Materials for Extreme Environments, at the AFOSR 2013 Spring Review. At this review, Program Officers from AFOSR Technical Divisions will present briefings that highlight basic research programs beneficial to the Air Force.
1. Ryan Stillwell
Materials Science Division
Lawrence Livermore National Laboratory
Livermore, CA 94550
Phone (cell): 619-729-2263, Phone (work): 925-422-8155
E-mail: stillwell4@llnl.gov
Research Interests
To exploit extreme environments of low temperature, high pressure and high magnetic
fields to explore the quantum interactions of highly correlated materials such as high-
temperature superconductivity, magnetism and topological insulators.
Education
• Doctor of Philosophy in Physics, Florida State University, December 2013
Advisors: Stan Tozer and Pedro Schlottmann, Dissertation: “Fermi surface
reconstruction in chromium at high pressure and high magnetic fields.”
• Master of Science in Physics, Florida State University, May 2009
• Bachelor of Science in Physics, Boston College, June 2006
Experience
v Postdoctoral Research Staff, Lawrence Livermore National Laboratory, July 2014-
present
o Investigate actinide and lanthanide systems under extreme conditions of high
pressure, low temperatures and high magnetic fields using designer diamond anvil
electrical transport and magnetic susceptibility pressure cells.
o X-ray diffraction studies performed at ambient and high pressures.
o High temperature synthesis of single crystals via flux growth techniques.
o Develop LabVIEW data acquisition and control program to perform magnetic
susceptibility and electrical transport measurements in a Montana instruments
closed-cycle helium refrigerator.
o Synthesis and characterization of uranium alloys for development of direct metal
write advanced manufacturing processes.
v Graduate Research Assistant, National High Magnetic Field Laboratory, Florida
State University, October 2006- December 2013
o Conduct research on actinides and related materials under extreme conditions using
diamond anvil and piston cylinder pressure cells. Research in DC magnetic fields to
45 Tesla, temperatures down to 20 millikelvin and pressures to 8 GPa was
performed during the course of my research.
2. o Complementary high pressure work in pulsed magnetic fields at Los Alamos
National Laboratory and HLD Dresden, Germany was undertaken.
o Improve quality of chromium and depleted uranium single crystals using high
temperature furnace annealing techniques in both sealed quartz ampoules and
flowing inert gas environments.
o Characterize sample quality and structure using a Laue back reflection camera and
single crystal X-ray diffractometer and maintenance of same.
o Single crystal flux growth technique
o Glovebox technique
o Mechanical drawings and shop practices
o Test and implement newly developed pressure cells for use in high magnetic fields.
o Sample preparation on submillimeter scale:
- Electrical Discharge Machining (EDM)
- Electropolishing
o Fabrication of submillimeter experimental components:
- Handmade gaskets for 0.6-1.2mm DAC culets using diamond epoxy and Zylon
- Resonant coils, 180µm in diameter, hand wound with 56 AWG Cu wire.
o Operate laser pressure calibration system for in-situ fluorescence spectroscopy over
the range 1.5-300K.
o Responsible for managing and maintaining 16 tesla Quantum Design Physical
Properties Measurement System (PPMS) for internal group use as well as
coordinating time for outside collaborators. This has included solving magnet
quench issues, making all vacuum lines leak tight, replacing circuit boards in the
main systems computer and creating an external interface with the system through
the fabrication of custom probes and electronics.
o Vacuum technology-mechanical, turbo, and leak detection (used, understand, and
repaired.)
o Cryogenic technology-VTI, He-3 and dilution refrigerator (used, repaired, and
understand.)
o Magnetic field environment (used, repaired, and understand.)
o Pressure cells-DACs and PCCs (used, repaired, and understand.)
o Trained on Integrated Safety Management (ISM) protocols.
v Graduate Teaching Assistant, Florida State University, September 2006-April 2007
o Instructor for the undergraduate introductory physics laboratories.
• Responsibilities:
- Give 20 minute introductory lecture on relevant theoretical framework
- Instruct and guide through laboratory exercise
- Grade lab reports.
v Undergraduate Research Assistant, Boston College, September 2005- May 2006
o Rebuilt a thermal vapor deposition machine for depositing thin films on samples.
Studied the heavy fermion system UPt3-xPdx.
3. o Gained experience with high voltage electronics design, high vacuum systems, and
machining and designing parts for fabrication.
Technical Skills:
o Characterization Techniques
• Neutron scattering
• X-ray diffraction
• Tunnel diode oscillator (penetration depth/surface conductivity)
• Torque cantilever (piezoresistive and capacitive)
• Electrical transport
• Hall measurements
• Heat capacity and specific heat
• AC susceptibility (vibrating sample magnetometer, modulation coil, SQUID)
o Cryogenics-Trained in proper use of:
• Dilution refrigerator
• Pumped 3
He/4
He liquid and vapor systems.
• Variable temperature insert (VTI)
• Closed cycle, helium refrigerator
• Liquefied argon, helium and nitrogen as pressure media.
o Materials Synthesis
• Flux growth techniques
• Czochrolski single crystal growth
• Arc furnace
• Quartz glass working
• Chemical processing and refining of samples
• Characterization of materials
• Thin film sputtering and plasma etching
o Fabrication
• Lathe and millwork
• Brazing
• Welding
o Safety Training
• Certified radiation worker level 2.
• Up-to-date training and clean safety record in laser, electrical, high pressure,
cryogenics, machine shop, magnets, chemicals, and crane operations.
• Helped write Integrated Safety Management protocol for diamond anvil cell and
piston cylinder cells.
Computer Skills:
o IGOR data analysis.
4. o AutoDesk three dimensional CAD.
o LabView.
o WinSpec.
o GSAS and EXPGUI refinement programs.
o Crystalmaker and Crystaldiffract.
o CrysAlisPro X-ray diffraction software.
o MultiVu software for Quantum Design PPMS and MPMS systems.
o Microsoft Office package (Word, Excel, Powerpoint).
o PC and Macintosh operating systems.
o Basic LaTeX typesetting.
o Installation and servicing of hardware components including processors and hard
drives.
Outreach:
o Worked with underrepresented scientists to accomplish mission of Open Doors Lab at
the National High Magnetic Field Laboratory in Tallahassee, FL.
o Tour guide at the Magnet Lab to educate general public about the importance of
scientific research.
o Exhibition presenter for the high pressure and pulsed magnet demonstration at the
annual Maglab Open House, which annually draws 3,000 members of the general
public to the lab.
Scholarly Contributions
Peer-reviewed Publications
1. “Superconducting Bi2Te: pressure-induced universality in the (Bi2)m(Bi2Te3)n series.”
Ryan L. Stillwell, Zsolt Jenei, Samuel T. Weir, Yogesh K. Vohra, Jason. R. Jeffries.
Physical Review B, under review, arXiv: 1511.02944 (2015).
2. “Strongly coupled electronic, magnetic and lattice degrees of freedom in LaCo5 under
pressure.” Ryan. L. Stillwell, Jason. R. Jeffries, Scott. K. McCall, Jonathon R. I. Lee,
Samuel T. Weir, Yogesh K. Vohra. Physical Review B, 92, 174421 (2015).
3. “Pressure-driven Fermi surface reconstruction of chromium.” R. L. Stillwell, D. E.
Graf, W. A. Coniglio, T. P. Murphy, E. C. Palm, J. H. Park, D. VanGennep, P.
Schlottmann, S. W. Tozer. Physical Review B, 88, 125119 (2013).
4. “A new oxytelluride: Perovskite and CsCl intergrowth in Ba3Yb2O5Te.” J. B. Whalen,
T. Besara, R. Vasquez, F. Herrera, J. Sun, D. Ramirez, R. L. Stillwell, S. W. Tozer, T.
5. D. Tokumoto, S. A. McGill, J. Allen, M. Davidson, T. Siegrist. Journal of Solid State
Chemistry, 203, 204 (2013).
5. “Using Voronoi tessellations to assess nanoparticle-nanoparticle interactions and
ordering in monolayer films formed through electrophoretic deposition.” A. J. Krejci,
C.G.W. Thomas, J. Mandal, I. Gonzalo-Juan, W.D. He, R.L. Stillwell, J.H. Park, D.
Prasai, V. Volkov, K.I. Bolotin, J.H. Dickerson. Journal of Physical Chemistry B 117,
1664 (2013).
6. “Transport spectroscopy of symmetry-broken insulating states in bilayer graphene.” J.
Velasco, L. Jing, W. Bao, Y. Lee, P. Kratz, V. Aji, M. Bockrath, C.N. Lau, C. Varma,
R. Stillwell, D. Smirnov, F. Zhang, J. Jung, A.H. MacDonald. Nature Nanotechnology
7, 156 (2012).
7. “Pressure dependence of the BaFe2As2 Fermi surface within the spin density wave
state.” D. Graf, R. Stillwell, T. P. Murphy, J. H. Park, E. C. Palm, P. Schlottmann, R.
D. McDonald, J. G. Analytis, I. R. Fisher, S. W. Tozer. Physical Review B 85, 8 (2012).
8. “A tale of two metals: New cerium iron borocarbide intermetallics grown from rare-
earth/transition metal eutectic fluxes.” P. C. Tucker, J. Nyffeler, B. H. Chen, A.
Ozarowski, R. Stillwell, S. E. Latturner. Journal of the American Chemical Society
134, 12138 (2012).
9. “Structural and magnetic analysis of nanocrystalline lead europium sulfide (PbxEuyS).”
S. Somarajan, M. A. Harrison, D. S. Koktysh, W. D. He, S. A. Hasan, J. H. Park, R. L.
Stillwell, E. A. Payzant, J. H. Dickerson. Materials Chemistry and Physics 134, 1
(2012).
10. “Nonmetallic gasket and miniature plastic turnbuckle diamond anvil cell for pulsed
magnetic field studies at cryogenic temperatures.” D. E. Graf, R. L. Stillwell, K. M.
Purcell, S. W. Tozer. High Pressure Research 31, 533 (2011).
11. “Metamagnetic transition in single-crystal Bi4Cu3V2O14.” H. D. Zhou, E. S. Choi, Y. J.
Jo, L. Balicas, J. Lu, L. L. Lumata, R. R. Urbano, P. L. Kuhns, A. P. Reyes, J. S.
Brooks, R. Stillwell, S. W. Tozer, C. R. Wiebe, J. Whalen, T. Siegrist. Physical
Review B. 82, 5 (2010).
12. “Metal to Semimetal Transition in CaMgSi Crystals Grown from Mg-Al Flux.” J. B.
Whalen, J. V. Zaikina, R. Achey, R. Stillwell, H. D. Zhou, C. R. Wiebe, S. E.
Latturner. Chemistry of Materials. 22(5): p. 1846-1853 (2010).
13. “Fermi surface of alpha -uranium at ambient pressure.” D. Graf, R. L. Stillwell, T. P.
Murphy, J. H. Park, M. Kano, E. C. Palm, P. Schlottmann, J. Bourg, K. N. Collar, J. C.
Cooley, J. C. Lashley, J. Willit, S. W. Tozer. Physical Review B, 80(24): p. 241101
(2009).
6. Conference Proceedings
♦ “Design and construction of a top loading dilution refrigerator probe for a
superconducting quantum interference device DC magnetometer.” J. H. Park, R. L.
Stillwell, T. P. Murphy, S. W. Tozer, E. C. Palm. in 25th International Conference on
Low Temperature Physics, edited by P. Kes and R. Jochemsen (IOP Publishing Ltd,
Bristol, 2009), Vol. 150.
♦ “Cerium doped bismuth antimony.” K. C. Lukas, H. Zhao, R. L. Stillwell, Z. Ren, C.
P. Opeil. MRS Proceedings, 1456, mrss 12-1456-jj01-04 (2012).
Conference Presentation
♦ “Discovery of superconductivity in Bi2Te: Evidence of universal behavior in an
infinitely adaptive series under compression.” International Conference on Magnetism,
Barcelona, Spain (2015)
♦ “Discovery of superconductivity in Bi2Te: Evidence of universal behavior in an
infinitely adaptive series under compression.” American Physical Society March
Meeting, San Antonio, TX (2015)
♦ “Evolution of the Fermi surface of chromium at high pressure and high magnetic
fields.” Research at High Pressure, Gordon Research Seminar, Biddeford, ME, (2012)
(invited)
♦ “Evolution of the Fermi surface of chromium at high pressure and high magnetic
fields.” Southeast Section of the American Physical Society, Tallahassee, FL. (2012)
Oral Presentations
♦ “Superconducting Bi2Te: pressure-induced universality in the (Bi2)m(Bi2Te3)n series.”
Postdoctoral seminar, Lawrence Livermore National Laboratory, Livermore, CA.
(2015)
♦ “Study of the Electronic Structure of α-uranium at High Pressure, High Magnetic
Fields and Low Temperatures.” UK/USA NSF Molecular Magnetism, EPR and High
Pressure Collaboration Conference. Edinburgh, Scotland, UK. (2010)
♦ “International Megagauss Science Laboratory, Institute for Solid State Physics, The
University of Tokyo, Kashiwa.” Post-doctoral and Graduate Student Presentations:
International Magnet Labs, National High Magnetic Field Laboratory, Tallahassee, FL.
(2009)
Poster Presentations
♦ “Discovery of superconductivity in Bi2Te: Evidence of universal behavior in an
infinitely adaptive series under compression.” Institutional Postdoctoral poster
presentation, Lawrence Livermore National Laboratory, Livermore, CA (2015).
♦ “Evolution of the Fermi surface of chromium at high pressure and high magnetic
fields.” Research at High Pressure, Gordon Research Conference, Biddeford, ME,
(2012)
♦ “Pressure-Driven Fermi Surface Reconstruction at the Spin-Flip Transition in
7. Chromium.” R. L. Stillwell, E. C. Palm, T. P. Murphy, J. H. Park, D. E. Graf, W. A.
Coniglio, D. VanGennep, M. Bernstein, M. E. Woods, P. Schlottmann, L. M. Riner, S.
W. Tozer. 24th
Joint AIRAPT and APS-SCCM International Conference on High
Pressure Science and Technology, Seattle, USA (2013).
♦ “Understanding the Actinides via a Multi-faceted Approach.” R. L. Stillwell, E. C.
Palm, T. P. Murphy, J. H. Park, D. E. Graf, W. A. Coniglio, D. VanGennep, M.
Bernstein, M. E. Woods, P. Schlottmann, L. M. Riner, J. –X. Zhu, S. P. Rudin, J. M.
Wills, S. W. Tozer. 2013 Stewardship Science Academic Programs Annual Review
Symposium, Albuquerque, NM, (2013).
Teaching
♦ Co-instructor “PPMS Magnetization” Lab Practical, 2011 Maglab Summer School,
National High Magnetic Field Laboratory, (2011).
Committees
♦ Low Voltage Safety Subcommittee, National High Magnetic Field Laboratory, (2013).
♦ Member of the Advisory Committee for the American Physical Society’s Topical Group
on Energy Research (2008).
Awards and Honors
♦ International Travel Award, Institute for Complex Adaptive Matter (ICAM), 2010
♦ Dean’s List, Boston College, 2005