Reprinting

Interview 01Vol.

Super High Resolution Electron Microscopes
Stimulate Progress in Materials Science

Yuichi Ikuhara
Professor, Institute of Engineering Innovation, School of Engineering,
The University of Tokyo
Director, Nano-Engineering Research Center

“The rational methods through calculation andobservation to artificially control the structureof lattice defects will certainly accelerate
future advances in materials science.”

Yuichi Ikuhara
Professor, Institute of Engineering Innovation, School of Engineering,
The University of Tokyo
Director, Nano-Engineering Research Center

Yuichi Ikuhara : Graduate of Kyushu University.
After working in Japan Fine Ceramics Centera n d C a s e We s t e r n R e s e r v e U n i v e r s i t y(USA), joined the University of Tokyo as an
associate professor in 1996. Assumed his
current position in 2003. In 2010 received theHumboldt Research Award (Germany) for his
work on the physical properties and hyperfine
structures of material interfaces. Concurrently
serves as a professor at the Advanced Institutefor Materials Research, Tohoku University, andas Principal Researcher at the Nanostructures
Research Laboratory of the Japan Fine
Ceramics Center. American Ceramic Society
Fellow and a member of the World Academyof Ceramics.

Super High Resolution Electron Microscopes
Stimulate Progress in Materials Science
Shifting from production based on experienceand intuition to rational manufacturing based on theory and evidence.
JEOL Super High Resolution Electron Microscopes support great strides
in materials science.
Exploring grain boundaries

have a significant impact on industry,

Industrial materials like metals andmaterials with new functions.”

contributing to the development ofceramics have a polycrystalline structure
consisting of many tiny crystallite grains.

So says Professor Yuichi Ikuhara ofThe interface between crystallites is calledInstitute of Engineering Innovation, Schoola grain boundary. Grain boundaries playof Engineering, the University of Tokyo.

a role in determining the properties of theHe has been working on grain boundaries

material, and have become an area ofat atomic level since he was a graduate

great interest in recent years.

student, and continues his researchwith a heavy emphasis on observations“Non-periodic structure , such as thea n d m e a s u re m e n t s u s i n g e l e c t ro n

crystal surface, interfaces, dislocations,microscopes.

and atomic vacancies, have their own
specific electronic structure. These aresources of functions that are not foundin perfect crystals. If we can clarify

Paradigm shift
in materials engineering

the atomic and electronic structure

The advent of spherical aberrationof the grain boundaries as well as thecorrection for scanning transmission

mechanisms of the functions, this wille l e c t ro n m i c ro s c o p e s ( S T E M ) w a s

a major breakthrough in this area ofresearch. Due to the nature of roundelectron lens, there is an unavoidable
blurring (spherical aberration) from theelectron lens. However, by utilizing nonaxial-symmetric magnetic fields generated
by multipole lens, it is possible to largely
eliminate this blurring, enabling direct,
super-high resolution observation ofobjects at the Angstrom level. The theory
behind this method has been known forsome time, but practical implementation
has been difficult. Since the late 90’s, thetechnologies to achieve this have beenrealized, and welcomed with delight by

HAADF-STEM image (left) and ABF-STEM image (right) of titanium oxide crystal with [110] orientation

the research community.

(Obtained with GRAND ARM).

Professor Ikuhara was one of those

It is possible to observe separately the adjacent oxygen atom columns in the ABF-STEM image

researchers.
“Figuring out why a material has a certain
functionality can now be explained at theAtomic structure model

atomic level. This is probably one of theAccelerating voltage 300kV
Super High Resolution Electron
Microscope image (Filtered)most significant paradigm shifts in thehistory of materials science.”
For example, it was known that adding

Atomic structure of siliconsmall amounts of the rare earth yttrium toalumina (aluminum oxide) greatly increases
the strength, but it was never fully explained

aberration correction has been harnessed

progressing on the defect structures

why this occurs. Professor Ikuhara

for a range as a steady succession ofand dislocations that form ceramic

introduced one of the first Japan madediscoveries.

crystal interfaces. Super-computerscommercial STEM systems incorporating

Professor Ikuhara continued to announce

are used to perform the theoreticalspherical aberration correction. Using thisimportant results of his analyses ofcalculations to design ceramics withinstrument, he observed and comparedgrain boundaries at the atomic level,

defect structures that are not found in

the alumina interfaces both before andmainly through publications in journals

existing materials. By observing theseafter the addition of yttrium. In this way,

like Nature and Science. In 2010, his

defect structures using the STEM

he confirmed that the yttrium atoms areachievements were recognized as thewith spherical aberration correction,

located periodically at specific sites of

Humboldt Research Award (Germany); in

it is possible to confirm whether

the alumina grain boundaries, and that2013 he was awarded a Commendation

the structures match the theoretical

the alumina ionic bonds were changedfor Science and Technology from thepredictions.

to covalent bonds. This discovery was

Minister of Education, Culture, Sports,

Professor Ikuhara’s eyes sparkle as hepublished in the journal Science in 2006.

Science and Technology.

remarks, “This is exactly opposite toSince then, the power of spherical

In recent years, research has been

the traditional approach of developingmaterials based on intuition and trial

Developing the instruments from theand error. The rational methods throughuser perspective is what gives rise to thecalculation and observation to artificiallyexcellent usability.”

control the structure of lattice defects willcertainly accelerate future advances inmaterials science.”

Innovation through IndustryAcademia Collaboration

Ultra high resolution observationof hydrogen atoms

Behind this advancement is a moreefficient research and development
system achieved through collaboration

Professor Ikuhara’s lab includes thebetween industry and academia.

world’s first ultra-high resolution electronSince 2005, The University of Tokyo andmicroscope GRAND ARM manufactured

JEOL have been operating a Business-by JEOL. Equipped with a cold cathode

Academia Cooperation Office. There aref i e l d e m i s s i o n e l e c t ro n g u n i n t h emore than ten JEOL electron microscopes,

standard configuration, with a maximum

including the GRAND ARM, installed ataccelerating voltage of 300 kV andUniversity of Tokyo facilities, supporting

incorporating the latest version of JEOL’s

the research of Institute of Engineering

own spherical aberration correctors,

Innovation, School of Engineering, theGRAND ARM is capable of STEM

University of Tokyo. Feedback fromresolution of 45 pm*.

the materials scientists who use these

Professor Ikuhara voices his approval.

instruments is quickly incorporated into
product design, contributing to the rapid“Even light elements like hydrogen andevolution over the past several years.

lithium can be observed in detail, evenwhen they are in close proximity. We can“There are many visitors from abroad

perhaps even say that the resolution iscoming to see in the Business-Academia

now sufficient.”

C o o p e r a t i o n O ff i c e G R A N D A R M ,focusing a lot of attention on its impact.

He is also appreciative of the usability

Disseminating the observation methodsof the human interface and the large

and obtained results throughout the world

specimen tilt angle.

may even lead to dramatic changes inevery area of manufacturing.”“There are a number of engineers in
the electron microscope group at JEOL

There are still more advances ahead in

whohave studied materials science.
本社・昭島製作所

the evolution of STEM.

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