Rare-metal-leanpermanent magnet

The Elements Strategy Initiative Center forMagnetic Materials (ESICMM)GL：Takashi Miyake,CD-FMat, AIST

Backgroundto theresearch

Points of theresearch

Outline of theresearch

1・Growing market for high-performance permanent magnets・Anticipation for novel materials beyond neodymium magnet・Anticipation for novel magnet materials that do not includecritical elements

Outline of theresearch

3・Understanding high saturation magnetization and highmagnetocrystalline anisotropybased on quantum theory・Eﬃcient materials discover y using a combination ofcomputational, data-driven, andtheoretical approaches・High magnetic properties of Fe-rich rare-earth magnetcompound NdFe₁₂N: prediction byﬁrst-principles calculations and visualization

Procedure formaterials design

Materials located around the peakposition in performance are searchedand targeted as candidate materialsafter their structural stabilities areexamined.
Among candidates, those possiblysynthesized are further investigatedtheoretically in detail .
Syntheses of thus predicted materialsand their characterizations are triedout.
Figure３ Saturation magnetic polarization JS of the system plotted against the lattice constant aand atomic number of a ﬁctitious atom Z. The ferromagnetic state is unstable in the region to theleft of the dashed line. Here a bcc structure is assumed, and the electron number corresponds tothe atomic number of ﬁctitious atoms. A dome-like structure appears around a = 2.65 A and Z = 26.4,where JS takes the maximum value of 2.66 T, which is much larger than that of Nd₂Fe₁₄B, is seen.

Main phaseNd2Fe14B

NdFe12N

Outline of theresearch4

Sub phases・Neodymium oxides・Amorphous

Main phase・High saturationmagnetization・High magnetocrystallineanisotropy・High Curie temperature

Sub phases

・Optimized microstructuresfor high coercivity

Ferromagnetism is unstable in theregion to the left of the dashed line.

Several hundreds of data pointsobtained by high-throughputab-initio calculation are visualized.

Requirements forhigh-performance magnet materialsMicrostructure

Search for maximum performance ofmagnets through ab-initio datacatalyst support

Visualization in Mechanismof magnetism

・Visualization of electron spin-density that may aﬀect the magneticproperties.
・Development of 3D-Printing technology that enables us to depictthe crystal structure and electron density in the transparent resin.
This helps us to get better understanding anddeep insights, supporting the creation of new ideas.

Figure１ High-performance permanent magnet materials require a main phase having highsaturation magnetization, high magneto crystallineanisotropy, high Curie temperature, and a subphase that blocks the magnetic coupling among main phases. Coercivity has strong positivecorrelation with the microstructure.

FeN

Outline of theresearch

2TiMechanism of magnetismin rare-earth magnet compounds

Transition metal

Figure 4 Diﬀerence in the electron spin-density is obtained by subtracting that of NdFe₁₁Ti fromthat of NdFe₁₁TiN. The diﬀerence near the N atoms is conspicuous, is seen.

3d electrons：Spin magnetic moment：Orbital magnetic moment

S3dRare earth elementFigure 2 High saturation magnetization and high Curie temperatures inrare-earth magnet compounds comefrom the 3 electrons of transitionmetals, whereas the 4 electrons ofrare-earth elements are the source ofstrong magnetocrystalline anisotropy.
The direction of the orbital magneticmoment of the 4 electrons is aﬀectedby the crystal ﬁeld produced by thesurrounding charge distribution.

S5dS4f

L4f

Nd

4f electrons

5delectrons

RoadmapApplications

・Discovery of novel magnet compounds and optimization ofchemical composition by machine learning / AI・Mechanism elucidation of coerciviry・Electric motors for xEVs(hybrid vehicles, electricvehicles etc.)・Wind turbines

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・Home electric appliances・Industrial robot・drone etc.

The Elements Strategy Initiative Centerfor Magnetic Materialsesicmm-info@ml.nims.go.jp

Elements Strategy Initiative forCatalysts and Batteries (ESICB)

NNovelAutomotive CatalystsUsing Less Noble MetalsU

GL：Tsunehiro Tanaka,

Graduate School of Engineering,Kyoto University

Backgroundto theresearch・Reducing the use of platinum- group metals (PGM) inautomotive catalysts is of practical importance.
・Thermal sintering of metal nanoparticles poses a signiﬁcantproblem to catalyst life.
・Catalytic active sites are thought to be the surface of noblemetal particles.

Outline of theresearch

Reduction of Pd usage by improvinga function of catalyst support

3

Model Reaction for purifying automotive exhaust gas

C3H6 + 4NO + 4CO + 9/2O2

Points of the ・Plasma preparation for Rh nanoﬁlm-coated metal honeycombresearchcatalysts・The catalytic activity of the Rh nanoﬁlm is markedly superior tothat of Rh nanoparticles.
・Improvement in catalytic performance using the function of acatalyst support.

1w

100

80

60

40

1 wtw % Pd/A/ l2O31 wtw % Rh/A/ l2O31 wtw % Pt/t/Al2O3

20

0100

200300400Reaction temperature / °C

NO conversion to N2 (%)

Paradigm shift in catalyst preparationand structure

10.5 wt% Pd/Mn-YbFeO3O3

100NO conversion to N 2 (%)

Outline of theresearch

2N2 + 7CO2 + 3H2O

C3H6: residual component due to gasoline, CO: component formed by incomplete combustion of gasolineNO: component formed under high temperature (> 1000 ºC) in engine

80604020
0100

500

5.0 wtw % Pd/A/ l2O3200300400500Reaction temperature / °C

40 nm

The catalytic activity of 0.5 wt% Pd/Mn-YbFeO3 is comparable to that of 5.0 wt% Pd/Al2O3.

PGM

PGM saltsٔsupportrpowdersrpowdersrgh surfrface arer arous structurerNP

pulsed arc pdepositiondeppos on (Figure３ (Left) NO conversion to N₂ over Pd catalyst supported on Mn-modiﬁed hexagonalYbFeO₃ (Pd/Mn-YbFeO₃).
(Right) TEM image of Pd/Mn-YbFeO₃ having hexagonal plate-like nanoparticles.

eectrode

Outline of theresearchsoluble saltssupportr

4

nanofilm

supportr ed catalystswaterw+binder

Development of novel catalystsupport havingoxygen storage capacity

slurryryslurryrhoneycomb

 Redoxx behavior of Srr3(Fe0.8Ni0.2)2O7-δ

40 μm coating160 μm honeycombceramic honeycomb

psuper ultra high densitythermal/mechanical stabilitytolerance against poisons Efficiency of NO reduction400

CO, C3H6N2 formaon / μmol g-1

coating/calcination

NO, O2Figure １ (Left) Conventional catalyst preparation via wet coating of powder containing metalnanoparticles.
(Right) Novel catalyst preparation via pulsed arc plasma deposition of active metal nanoﬁlms ontometal foil substrates.

300

200

1000Pd/Al2O3 Pd/Sr3Fe2O7-δPd/Sr3(Fe0.8Ni0.2)2O7-δ Mechanism for NO reduction on Sr3(Fe0.8Ni0.2)2O7-δ1/2 N2NONPd

Outline of theresearch

Catalytic performance of Rh nanoﬁlm andRh nanoparticle catalysts

2VOVO

VO

Oxygen vacancy sitePdOVOVOVOVOVO

VOVOOxygen vacancy site

Figure 4 (Upper left) Structural change of Sr₃(Fe₀.₈Ni₀.₂)₂O₇ - during the puriﬁcation of automotive exhaust gas (Upper right) Eﬃcienc y of NO reduc tion at ox ygen vacanc y site inPd/Sr₃(Fe₀.₈Ni₀.₂)₂O₇- (Below) Mechanism for NO reduction in Pd/Sr₃(Fe₀.₈Ni₀.₂)₂O₇- .
δ& 2 1 2 Ѝ& 2   ½1 100

Rh nanofilmmetal foil

1 nm20 μm1 nm

δpowderNOCOdrycoatingg

60

Rh nanoparticleNPRoadmap

Structurewet coating

40200200

300

400

500

100

Temperature / éHigh turnoverfrequency (TOF)

Low turnoverfrequency (TOF)7034

Rh nanoﬁlm

Rh nanoparcleδporous support

RhnanofilmOverlayer

80

Conversion / %Rh nanoparticle

Total surfacearea/cm2 cm-3Rh loaded/μg cm-3Rh surfacearea/cm2 cm-3

100×104250

Applications

・Elucidation of the reaction mechanisms for nanoﬁlm catalysts・Development of nanoﬁlm catalysts for various chemicalreactions・Development of novel catalyst materials using the crystalstructure of catalyst supports・Automotive catalysts・Microreactors and smart reactors

164

86

TOF@295 °C/min-1 site-1

12924

Activity

164

Contact us hereFigure 2 Catalytic performance of a Rh nanoﬁlm-coated honeycomb catalyst compared with aconventional honeycomb prepared by wet coating. 0.1% NO, 0.1% CO, N₂ balance. GHSV = 1.2×105 h-¹.

Elements Strategy Initiative forCatalysts and Batteries, Kyoto Universityadmin@esicb.kyoto-u.ac.jp

Elements Strategy Initiative forCatalysts and Batteries (ESICB)

Fire-Extinguishing OrganicElectrolytesfor Safe Batteries

・Fire incidents with explosions occurring in lithium-ionbatteries have been problematic.
・The simple addition of ﬂame-retardant solvents signiﬁcantlydegrades the battery cycle.
・How can we produce better batteries with a high level ofsafety?

Backgroundto theresearch

Points of theresearch

GL：Atsuo Yamada,

School of Engineering,The University of Tokyo

Outline of theresearch

3Comparison of ﬂammability

・Highly concentrated ﬁre-extinguishing TMP-based electrolytecan form a very robust passivation ﬁlm on the anode surface.
・This enables an excellent battery life of more than 1,000charge-discharge cycles with negligible degradation.
・Computational analysis using the K computer has revealed theformation mechanisms of stable passivation ﬁlm.

Outline of theresearch

General electrolytes

New highly concentratedelectrolytes

1.0 M NaPF6 /EC:DEC (1:1)

3.3 M NaFSA/TMP

Toward ultimate safetywhile retaining repeated cycle stability

1Commercial electrolyte：

TMP electrolyte：

Highly concentratedTMP electrolyte :× Flammable○ Flaｍe retardant○ Flaｍe retardantFigure 3 Flame tests on conventional 1.0 M NaPF₆/EC:DEC (1:1 by vol) electrolyte (left) andlaboratory-made 3.3 M NaFSA/TMP electrolyte (right)

Outline of theresearchElectronic structures ofhighly concentrated electrolytes

4○ Solvent-derivedSEI ﬁlm

× Interface cannotbe formed○ Salt-derivedSEI ﬁlm

3

3.3 M NaFSA/TMP

Outline of theresearch

PDOS

Figure１ Electrolyte design concept for a safer battery. By ultimately simple strategy of increasing salt-concentration, interfacial character is dramatically modiﬁed to realize very stableoperation, and many of the solvents are functionalized (ﬁre-extinguishing TMP this time).

TMP1Repeated cycle stability ofhard carbon negativeelectrode for Na-ion batteries

22LUMO

FSA-0-202

4

6Hard carbon Na

300

C/51 00

25080200

3.3 M NaFSA/TMP60

150

401005020

1.0 M NaPF6/EC:DEC

000200400

6 00

80 01 000

Efficiency / %Capacity / mAh g−1

Energy / eVFigure 4 Electronic structures and coordination structures (insets) of 3.3 M NaFSA/TMP solutionsobtained with DFT-MD simulations. Na+ cations, FSA− anions and TMP solvents are shown inorange, blue and grey, respectively. The pDOS, projected density of states, shows that LUMO arelocated at FSA and that the FSA is attacked ﬁrst upon reduction to form a passivation ﬁlm.

Roadmap

12 00

Cycle number3.03.03.3 M NaFSA/TMP

1.0 M NaPF6/EC:DEC170th

2.57th140thVoltage / V1

Voltage / V

2.5・Paradigm shift of electrolyte concept・Cost-cutting and industrial development・Optimization for mass production

2.01.51.01200th

7th2.0Applications

1.51.00.50.5・Consumer batteries・Batteries for vehicles・Stationary batteries

0.00.005010015020020Capacity/ mAh g−1250050100150200250

Capacity / mAh g−1

Figure 2 Capacity retention during repeated cycling of a hard-carbon anode for an Na-ionbattery; the organic electrolyte developed in this study (3.3M NaFSA/TMP) achieved stablecharging/discharging for more than 1,200 cycles (over a year and a half)Contact us hereElements Strategy Initiative for Catalystsand Batteries, Kyoto Universityadmin@esicb.kyoto-u.ac.jp

CConcurrentenhancement of strengthand ductility in bulk nanostructured
ahexagonal metalshBackgroundto theresearch・Concurrent enhancement of strength and ductilit y instructural materials is essential for guaranteeing a safe andsecure society.
・Applications for strong, light-weight titanium and magnesiumalloys have been limited by poor ductility owing to theirhexagonal crystal structures.
・Creation of innovative hexagonal metals through bulknanostructuring rather than the addition of critical alloyingelements is targeted.

Points of theresearch・Fully recrystallized titanium and magnesium alloys withvarious average grain sizes down to the sub-micrometer scalewere successfully fabricated.
・Concurrent enhancement of strength and ductility wassuccessfully achieved in bulk nanostructured titanium andmagnesium alloys.
・Atomistic mechanisms of the superior mechanical propertiesin bulk nanostructured materials were clariﬁed throughstate-of-the-art experiments, such as transmission electronmicroscopy and neutron diﬀraction, as well as theoreticalcalculations.

Outline of theresearch

1

Fully recrystallized magnesium alloys withvarious average grain sizes

Outline of theresearch

3Elements Strategy Initiative forStructural Materials（ESISM）GL：Nobuhiro Tsuji,

Graduate School of Engineering,Kyoto University

Mechanism of enhanced ductility inbulk nanostructured materials

Figure３ Transmission electron micrographs of ultraﬁne grained magnesium alloy sample withaverage grain sizes of =0.98 μm after tensile deformation to a strain of 0.095. (a) Bright-ﬁeldimage observed along [10-10] zone axis. (b) Bright-ﬁeld and (c) corresponding dark-ﬁeld imagesobserved under two-beam condition with diﬀraction vector = (0002). (d) Weak-beam dark-ﬁeldimage of the rectangular area in (b) at a higher magniﬁcation. Highly dense, unusual dislocationswith c-component can be observed. Such dislocations are presumed to be nucleated at grainboundaries when the stress level increases.

Outline of theresearch

4Comprehensive understanding ofductility enhancement in bulknanostructured metalsunder the new concept ofFigure １ Magnesium-alloy samples having various average crystal grain sizes fabricated by high-pressure torsion (HPT)followed by recrystallization annealing treatments at the given temperatures and durations. (Top) Inverse pole ﬁgure (IPF)maps by electron backscatter diﬀraction (EBSD). Colors correspond to crystallographic orientations of grains. (Bottom) Grainboundar y (GB) maps in which the blue and green lines correspond to high angle and low angle grain boundaries,respectively.

Outline of theresearch

2

Concurrent enhancement ofstrength and ductilityin bulk nanostructured materials

Figure 4 Unique plastic deformation mechanisms diﬀerent from primary dislocation glide, suchas non-primary dislocation glide, deformation twinning, and martensitic transformation, havebeen experimentally found to take place in bulk nanostructured materials. These mechanisms canbe comprehensively explained under the new concept of. When a large enough stress isapplied, collective atomic motion occurs at lattice imperfections such as surfaces and grainboundaries, which eventually leads to the nucleation of plastic deformation. Similar phenomenaare thought to take place at the front of the plastic deformation.

RoadmapApplications

・Concurrent enhancement of strength and ductility in bulknanostructured steels based on the new concept of.
・Fundamental understanding ofin other materialshaving a variety of chemical bonds in order to overcome theirbrittleness.
・Vehicles and aircrafts・Structures・Biomaterials

Contact us hereFigure 2 Comparison of stress-strain curves for Mg-alloy specimens having four diﬀerentaverage grain sizes .

Elements Strategy Initiative forStructural Materials,Kyoto Universityadmin@esism.kyoto-u.ac.jp