BY LAURA MILLSAPS

HE HOUSEHOLD REFRIGERATOR, SITTING IN THE
corner of virtually every U.S. kitchen, has been

essentially the same for almost 100 years; air-

conditioning, based on the
same technology, almost 75 years.
But with the traditional vapor-

compression model reaching its limits
for advancement in efficiency, cooling
still eats up as much as one quarter of
U.S. daily energy consumption.

0, what if refrigeration systems
could be even better? What is the
future of cool?

Laboratory,

SE

scientific community, believes it could be

Ames together with
the larg
magnetic cooling, a refrigeration system which exploits
the magnetocaloric effect—a temperature change of a
material caused by exposing it to a changing magnetic
field. Scientists have been attempting for years to push this
promising energy-efficient alternative over the gap between
fundamental research and applied technology.

This April, Ames Laboratory Chief Research Officer
Duane Johnson and scientist Vitalij Pecharsky helped
organize and participated in a workshop, Advancing

14 Inquiry Issue 1 | 2015

Materials for Efficient Cooling 2015, hosted by the
Maryland Nanocenter at the University of Maryland.

There, Pecharsky said, academia, national laboratory
scientists, and representatives from industry met to discuss
the current limitations of all three types of solid state
cooling based on one of three so-called caloric effects

electrocaloric, elastocaloric, and — magnetocalorics,
Pecharsky's area of research interest.

he first big question is whether this technology is still

worth pursuing, and the overwhelming sentiment is ‘yes,
said Pecharsky of the workshop. “The potential gains in
energy efficiency are too significant to ignore.”

Almost 20 years ago, Ames Laboratory scientists Karl A.
Gschneidner, Jr. and Pecharsky announced groundbreaking
progress in magi refrigeration—they discovered a
gadolinium alloy that allowed magnetocaloric cooling to
occur at room temperature, and a prototype refrigeration
system was built in partnership with Astronautics
Corporation of America Ltd.

Since then, research at Ames Laboratory and globally
has progressed, and there are occasionally demonstration
models put forth by industry, but there is still no currently
known commercially available product that uses a magnetic
cooling system



Anderson named 2015 TMS Fellow

Iver Anderson, Ames Laboratory metallurgist, has
been named a 2015 Fellow of The Minerals, Metals
& Materials Society (TMS). Anderson was one of
six Society members who have earned the highest
award bestowed by TMS, which recognizes members
for their outstanding contributions to the practice of
metallurgy, materials science and technology. The 2015
Fellows were recognized at the 144th TMS Annual
Meeting & Exhibition held March 15-19, 2015.
Anderson was specifically recognized for his inventiveness
that led to lead-free solder used in all electronic devices;
for seminal contributions to: (1) gas atomization of
metallic and polymeric materials, (2) powder metallurgy

technology, and (3) rapid solidification processing of

ional

a wide variety of materials; for long-time profi
leadership as a member of the TMS Board of Directors

and chair of numerous TMS technical committee:
for contributions to education, especially for graduate

student advising.

Stephens wins CYtation Award

TMS President Hani Heneim, left, presents Iver Anderson with
his TMS Fellow certificate during the society’ annual meeting.

Ames Laboratory Systems Support Specialist IV Doug
Stephens received a 2015 Iowa State University CYtation
Award which is presented to ISU Professional and Scientific
staff in recognition of individual achievements above and
beyond the calll of duty, and/or extraordinary performance, or
acts in such a way as to make a notable difference in
the institution.

Stephens was cited for his leadership in helping
upgrade Ames Laboratory's network connections from
one gigabit to ten gigabit throughout the four main Ames
Laboratory buildings and to the Internet Service Providers
(ISU and Energy Sciences Network)

In nominating Stephens for the award, Ames I
Information Systems manager Diane DenAdel said
expertise was essential to develop the master plan, implement
new switches, and upgrade or modify existing network
switches. Other Ames Laboratory Information Technology
personnel were involved with various parts of the project,
and Doug coordinated the efforts to ensure the success
of the project. Doug's efforts made a real difference to the
Ames Laboratory and to ISU. It would have been difficult
to complete all of this work without Doug's attention to detail
and dedication to the overall project.”

ISU Senior Vice President and Provost Jonathan
Wickert, left, presents Ames Lab's Doug Stephens
with the CYtation Award.

Inquiry Issue 1 | 2015 5


Magnetism at Nanoscale

S THE DEMAND GROWS FOR EVER SMALLER,

smarter electronics, so does the demand for

understanding materials’ behavior at ever-

smaller scales. Ames Laboratory ph

are building a unique optical magnetometer to probe
magnetism at the nano- and mesoscale.

The device, called a NV-magnetoscope, makes
use of the unique quantum mechanical properties of
nitrogen-vacancy (NV) centers in diamond. The low-
temperature NV-magnetoscope setup incorporates
a confocal microscope (CFM) and an atomic-force
scanning microscope (AFM).

The NV-magnetoscope will be able to sense the
extremely weak magnetic fields of just a handful
of electrons with the spatial resolution of about 10
nanometers.

“We want to determine magnetic textures more
precisely than ever before, at smaller scales than ever
before,” said Ames Laboratory physicist Ruslan Prozorov.
“Our hope is to understand nano- and mesoscale

magnetism, learn how to control it and, eventually, use
that to create a new generation of technologies.”

Experimental physicists Ruslan Prozorov (left)
and Naufer Nusran (right) and theoretical physicist
Viatcheslav Dobrovitski (center) are collaborating
to bring the preciseness of quantum mechanics to
measuring nanoscale magnetism in Ames Laboratory's
NV-magnetoscope. The development of the NV-
‘magnetoscope is a flagship effort of Ames Laboratory's
“Magnetic Nanosystems: Making, Measuring,
Modeling and Manipulation” research team, led by
Prozorov. Theoretical work is done by Dobrovitski and
hands-on experimental work is done by a dedicated
postdoctoral researcher, Nusran, who has built
the experimental setup, the first NV-centers optical
magnetometer fitted into the low-temperature AFM/CFM
system, first of its kind in the United States acquired from
Germany’ Attocube.

10 Inquiry Issuer | 2015

Green Laser Light Excites the NV Center

“Electrons start at low-energy quantum states. And the green
laser light ‘kicks’ them to a high excited state. The rules of quantum
mechanics say that those electrons must return back to the lower
energy level. If an electron was excited from a non-magnetic level,
it always emits red light. However, if it was excited from one of
the low-energy magnetic levels, it most likely relaxes back without
any emission.

Microwave radiation is used to scramble electrons between
low-energy magnetic and non-magnetic states, reaching maximum
population of the magnetic states when the interlevel energy
difference matches microwave energy. Therefore, by scanning
microwave frequency, red fluorescence will cause double-dip
spectra, corresponding to two magnetic energy levels, split by the
magnetic field (called Zeeman splitting). The distance between the
dips is proportional to the magnetic field at the location of an NV
center,” said Prozorov.

Detector Counts Red Photons

As excited electrons lose energy and return back to the low-
energy state, they emit red light. A detector counts the number of
red photons.

—~
NV Centers “Feel” Sample’s Magnetic Fields

A roughly 100-nanometer-long diamond containing NV centers
is attached to the AFM tip. The confocal microscope focuses on a
single NV center, collecting red photons only from one tiny area while
blocking out outside “noise.” The sample of interest is scanned below
the NV center. The NV center “feels” the variation of magnetic fields
produced by the sample.

“When the sample of interest is brought close enough to an NV
center, the sample's magnetic field is extended to the location of
the NV center and affects the center's quantum energy levels. By
accurately moving the sample in two dimensions close to the NV
center, we can reconstruct the magnetic field intensity map produced
by the sample. This, in turn, gives access to the magnetic properties
of the sample itself,” said Prozorov.

mz


Top: The new Sensitive Instrument Facility sits near the
existing Applied Science II building in the background.
Right: Interior view of one of the o|

Construction of the SIF is wrapping up, however at this
point, only four of the six instrument bays are being finished
and will house the equipment listed earlier. The remaining
space will be allocated based on equipment needs and
compatibility that allows the best utilization of that space. A
multi-stage commissioning process will take place to insure
that the building and its electrical and mechanical systems
perform according to specifications before the Lab takes
ownership.

“Scheduling could be a bit of a dance to make sure that all
of our ISU partners who have funded the equipment get their
appropriate access,” Kramer said. “I anticipate that it will be
in use 24/7. The facility is our space to manage and users will
be brought on as Ames Lab associates with all the requisite
training in terms of safety, policies and procedures, and how
to operate the equipment.”

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“One benefit of the new equipment is that it allows one to
observe the operation of, and even operate, the instruments
remotely,” he continued. “I'm considering setting up a location
on campus where samples could be dropped off. Researchers
would book time on the equipment, their sample would be
loaded and then control of the equipment would be handed
off to them remotely. They could perform their scans without
setting foot in the SIF.”

“Obviously, we have a lot of details to work out,” Kramer
said, “but this facility will provide a significant boost to the
characterization capabilities at both Ames Laboratory and
Towa State Univers

Inquiry Issue 1 | 2015



J Renal SOA f

EARS OF PLANNING WILL SOON COME TO FRUITION
when the Sensitive Instrument Facility (SIF) opens
its doors later this year. The $10 million state-of-the-
| art building, Ames Laboratory's first new research

> facility in more than 50 years, will house a new
array of electron microscopes that will provide
researchers an unprecedented close-up look at
materials at the atomic level.

“Everything is coming together,” said Matt Kramer,
Materials Sciences and Engineering Division Director at
‘Ames Laboratory. “We've been able to pull together the
necessary funding through partnerships with Iowa State
University and the Department of Energy to equip the SIF
with what we need to take our research capabilities to the
next level

In addition to an existing transmission electron microscope
that will be moved to the new facility and upgraded with
newer software and detectors, three additional pieces of
equipment will be purchased. Using DMSE equipment
funds and an FY14 midyear equipment addition from DOE,
‘Ames Laboratory will purchase a field-emission scanning
electron microscope (FE-SEM) for roughly $800,000.

The other two pieces—a focused ion beam microscope,
known as a FIB ($1.7 million) and an aberration-corrected
scanning transmission electron microscope or STEM ($3.5
million)}—are now funded as well. DOE allocated funds to
help purchase the FIB.A coalition of Iowa State’s Departments
of Materials Science and Engineering, Chemical and
Biological Engineering, Mechanical Engineering, Chemistry,
and Physics, the Deans of Liberal Arts and Sciences and

6 Inquiry Issue 1 | 2015

This facility will provide
a he nt boost to
plik aracterization
silt ies at both

Arne Laboratory and
Iowa State University.

Engineering, the Senior Vice President and Provost, and
the Senior Vice President for Business and Finance all
contributed to the funding of the FIB and the STEM.

“We are reviewing capabilities of the various manufactures

and developing required specifications in preparation for
placing an order,” Kramer said.

Once the order is placed for the three new pieces of
equipment, the work of moving the existing Tecnai TEM
and the supporting sample preparation equipment will
be scheduled so as to minimize the down time for current
microscopy work. Once the new facility is operational, the
other two existing scanning electron microscopes and an
older TEM, now obsolete, will be removed and the lab space
in Wilhelm Hall reclaimed for other purposes.




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Ames Laboratory
rials & Energy Solutions



ion

for Synchrotron Light Source

BY KERRY GIBSON

T'S OFTEN SAID THAT NECESSITY IS THE MOTHER

of invention. Such was the case for Ames Laboratory

physicist Adam Kaminski who took the research

challenge he was facing and tured it into a new
solution that will help advance his research.

‘Two years ago the National Science Foundation closed
the synchrotron in Stoughton, Wisc. More recently,
Brookhaven National Lab closed its synchrotron light
source to make way for a more advanced and powerful
facility. Concerned that this would leave him without the
low-energy light source he needed to study the electronic
properties of new materials, he improvised, and the result
was the development of a new technique that provides a
homegrown, laboratory-based solution.

Kaminski uses a technique called angle-resolved
photoemission spectroscopy (ARPES) in which light energy
(photons) is directed at a sample being studied. The photons

Adam Kaminski stands next to the equipment
he assembled to conduct angle-resolved
photoemission spectroscopy in his lab using
laser light and a potassium beryllium
fluoroborate crystal to excite electrons in
the material being studied.

12 Inquiry Issue 1 | 2015




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|
2

8 Inquiry Issue 1 | 2015



Bakac receives
Distinguished Service Award

Retired Ames Laboratory scientist Andreja Bakac was
recognized for her years of service to the Department of Energy
with The Secretary's Distinguished Service Award. Bakac received
the award certificate and medallion at an informal presentation at
Ames Laboratory on March 6.

The certificate, signed by Secretary of Energy Ernest Moniz,
reads: “In recognition of your outstanding research into the
mechanistic chemistry of small molecule activation with transition
metals and your dedication to the mission of the Department of
Energy and the Ames Laboratory: With sincere gratitude for your
38 years of service and stewardship to the Department of Energy,
Dr. Andreja Bakac is awarded the Secretary's Distinguished
Service Award.”

This distinction is given in recognition of continuous and
distinctive achievements, within or beyond an individual's area of

responsibility, which are of substantial value to the DOE.

Catherine Meis

4

Inquiry Issue 1 | 2015

Andreja Bakac

Former SULI student named
Goldwater Scholar

Iowa State University student Catherine
Meis has been named a 2015 Goldwater
Scholar, the nation’s premier undergraduate
scholarship in mathematics, natural
sciences and engineering. Meis, a former
Ames Laboratory Science Undergraduate
Laboratory Internship (SULI) program
participant, is a third-year student, majoring
in materials engineering with a minor in
bioengineering. Meis studied under Reza
Montazami and Nastaran Hashemi, ISU
assistant professors of mechanical

engineering.




THERE'S A LOT GOING ON THESE DAYS AT THE AMES LABORATORY.

ERE IN THE FINAL STAGES OF CONSTRUCTION on our new Sensitive Instrument

Facility, a nearly $10 million building that will house an array of state-of-the

art electron microscopy equipment. It's Ames Laboratory's first new research

facility in more than 50 years. Through a combination of funding sources,

including the Department of Energy and our contractor, Iowa State University, the SIF

will be outfitted with three new pieces of equipment and an existing transmission electron
microscope will be moved and upgraded.

The SIF will significantly enhance our capabil

at the atomic s«

s to characterize materials, particularly
le. By better understanding the electronic, atomic and molecular structure

of new materials, our researchers can draw correlations between those structures and the
materials’ properties, such as magnetic, electronic and photonic. You can learn more about
the SIF and take a virtual tour of the facility on page six.

And although it’s the largest, the SIF isn’t the only new thing at the Ames Laboratory.
Physic
magnetoscope that uses defects in diamond's crystal structure—nitrogen-vacancy centers—to visualize
the magnetic fields produced by magnetic nanostructures. You can find out more about this on page 10.

When another of our physicists, Adam Kaminski, found

‘ist Ruslan Prozorov’s research group has begun collecting data with a new, nitrogen-vacancy

that access to synchrotron beam lines was becoming limited,
he set out to create an alternative method to conduct angle-
resolved photoemission spectroscopy, or ARPES. Using laser
light, Kaminski developed a way to study a material’s electronic
properties right here at the Ames Laboratory, providing both
easier access and higher resolution than previously possible.
Read about his ingenious discovery on page 12.

‘Ames Laboratory has been a major player in the discovery of

giant magnetocaloric materials—compounds that heat up when
subjected to a magnetic field, then cool when the field is removed.
These materials show promise as a possible replacement for traditional gas-compression technology used
in refrigeration and cooling. Our chief research officer, Duane Johnson, and scientist Vitalij Pecharsky
recently headed up an international workshop to discuss the current state of these materials and how to
advance the technology to make it commercially viable. To learn about the outcome of those workshop
discussions, turn to page 14.

Materials discovery, design and synthesis are strengths of the Ames Laboratory and a major reason
why our Division of Materials Sciences and Engineering (DMSE) is our largest program. Theoretical
models help drive experiments to develop new materials, which in turn—through characterization—help
to further refine those theoretical models. Our suce:

in doing this will be evaluated in July as DMSE
undergoes its triennial program review.

Given the advances we're making in the areas I've mentioned here, as well as success on a range
of individual projects, we feel we're in a strong position to continue to be a world leader in creating
materials and energy solutions.

Aol lef

Adam Schwartz, Director

Inquiry Issue 1 | 2015 3


Steve Kary
Kerry Gibs
Brechan Ger
Laura Millsap
Grant Luhman

Ames Laborator
through the e

in the 194(

for atomic energy,

given the Lab intemational cre
actively involved in innovative re
and the quick transfer of such t
Lab stimulates creative thought

educating and training tomorrovl

Future of Cool

/
Si

Copyright 2015 by Ames Laboratory. All rights Editor, Inquiry
reserved. For additional information about Ames

Laboratory or topics covered in this publ
please contact

lated problems
and physies. Established
e high-purity uranium metal

ional concern, Ames Laboratory scientists are
the development of applied technologies

cated within a university environment, the

wviding solutions to complex problems and

ation, 111 TASF

Ames, Iowa 50011-3020

www.ameslab.gov

Inquiryis published biannually by the Ames
Laboratory Office of Public Affairs. Towa
State University operates Ames Laboratory
for the U.S. Department of Energy under
contract DE AC02 07CH11358.

Us. DEPARTMENTOF | Office of

@ ENERG Science





INQUITY-0:;

Ames Laboratory
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