Modern Methods in the Study of Nanomaterials Marcel MiGLiERiNi Slovak University of Technology, Bratislava and

Centre for Nanomaterials Research, Olomouc [email protected]

ww.nuc.elf.stuba.sk/bruno

Contents I.

Nanocrystalline Alloys

II.

Structural Characterization

III. Unconventional Methods

Мы обнаружили много чудес. Мы даже привыкли к ним. Мы научились ими пользоваться. Но мы до сих пор не понимаем как они устроены. А. Стругацкий, Б. Стругацкий

Part I. Nanocrystalline Alloys

We have discovered many oddities. We have even get used to them. We know how to use them. But up to now we do not know how are they constituted.

Nanostructured Materials l

at least one dimension below 100nm

H. Gleiter, NanoStructured Materials 6 (1995) 3

Magnetic Properties l

nanocrystalline grains l l

nc-FINEMET

origin of soft magnetic properties thermal stabilization of the structure

NANOPERM Co-am HITPERM

l

1988: FINEMET: FeCuNbSiB l

l

1990: NANOPERM: FeMB l

l

Yoshizawa Y, Oguma A, Yamauchi K J Appl Phys 64 (1988) 6044

Fe-Co ferrites

Si steel

Suzuki K, Kataoka N, Inoue A, et al. Mater Trans JIM 31 (1990) 743

1998: HITPERM: FeCoZrB l

Fe-am

Willard M A, Laughlin D E, McHenry M E, et al. J. Appl. Phys. 84 (1998) 6773

A. Makino, A. Inoue and T. Masumoto Mater Trans JIM 36 (1995) 924

Applications

core ribbons

magnetic shielding

transformer

sensors

Preparation l

rapid quenching (planar flow casting) l amorphous precursors l

l

ribbon-shaped

controlled crystallization

1477 °C liquid metal

melting furnace induction coil

ceramic nozzle

35 m/s air side

casting wheel amorphous ribbon

wheel side

Problems to Solve l

nanocrystalline alloys l l l

perspective materials for practical applications superior to metallic glasses (thermal and time stability) tailoring of required properties

l

structure affects also magnetic properties l structure depends on: l l

composition à constituent elements amount of crystalline grains à way of preparation (annealing conditions)

l

structural features should be understood

Structural Features l

methods of investigation l

macroscopic l l l

l

microscopic (atomic scale) l l l

l

differential scanning calorimetry – DSC X-ray diffraction – XRD diffraction of synchrotron radiation – DSR transmission electron microscopy – TEM, HREM, CSTEM electron diffraction – ED atomic and magnetic force microscopy – AFM, MFM

local probe methods (nuclear scale) l l l

Mössbauer spectrometry – TMS, CEMS nuclear magnetic resonance – NMR positron annihilation spectroscopy – PAS

„Tento způsob léta“, děl vposled odvraceje se od přístroje Celsiova, „zdá se mi poněkud nešťastným.“ V. Vančura

Part II. Structural Characterization

“The mood of this summer” he uttered finally turning away from the instrument of Celsius, “ seems to me a bit distressful.”

Differential Scanning Calorimetry l

Fe76Mo8Cu1B15 structural relaxation

B C D E FG

heat power

A

H

M J K

I

diffusion-like precrystallization effects

L

Tx1

normal grain-growth-like formation of α-Fe nanocrystallites in amorphous matrix diffusion controlled grain-growth of already created α-Fe nanocrystallites

RT

300

400

500 o

temperature ( C)

600

700

diffusion controlled nucleation and growth-like precipitation of γ-Fe(Mo)

X-ray Diffraction l

Fe91-xMo8Cu1Bx x = 12

x = 15

x = 17

o

650 C o

600 C o

550 C o

510 C o

450 C o

410 C a.q. 20

40

60

2Θ (deg)

80

100

20

40

60

2Θ (deg)

80

100

20

40

60

2Θ (deg)

80

100

Diffraction of Synchrotron Radiation l

BESSY KMC-2: 7 keV (1.78 Å) l

linear heating (10K/min) 300 – 1080 K

In situ Crystallization l

Fe79Mo8Cu1B12

M. Miglierini, et al.: Hyp. Int. 183 (2008) 31

air side

wheel side

Surfaces of the Ribbon 60 air-side wheel-side

wheel side

air side

relative area (%)

50 40 30 20

0.64 vol.%/deg 1.1 vol.%/deg

10 0 a.q.

300

400

500

600 o

annealing temperature ( C)

l

Fe79Mo8Cu1B12

Transmission Electron Microscopy l

HREM

Fe76Mo8Cu1B15 450oC

470oC

550oC

550oC

650oC

10nm

CS TEM + ED l

air side

Fe79Mo8Cu1B12 l l

layer thickness < 1 µm as-quenched

wheel side

am + bcc Fe (100) – bcc Fe(Mo)

(110) + (100) bcc Fe(Mo) B2Mo2Fe

Atomic Force Microscopy l

Fe79Mo8Cu1B12 l l

zmax = 35 nm

as-quenched alloy scanned area 1 x 1 µm2 zmax = 46 nm

air side

wheel side

Atomic Force Microscopy 470oC

530oC

410oC

650oC 0,00

370oC heat flow (W/g)

-0,05 -0,10 -0,15 -0,20 -0,25 -0,30 100

200

300

400

500

temperature (°C)

600

700

l

Fe79Mo8Cu1B12

Magnetic Force Microscopy l

air side Fe79Mo8Cu1B12

as-quenched AFM

MFM

7 x 7 µm

650 oC/1 hr. AFM

MFM

38 x 38 µm

Magnetic Force Microscopy l

as-quenched (Fe0.5Co0.5)79Mo8Cu1B12 wheel side

air side AFM

MFM

5 x 5 µm

AFM

MFM

3 x 3 µm

Mössbauer Spectrometry l

as-quenched Fe91-xMo8Cu1Bx 1.14

1.2

1.1

1.0

air side

1.12 1.10 1.08 1.06 1.04 1.02

1.08

relative emission

air side

relative emission

relative emission

1.3

wheel side

1.04 1.02

1.08

wheel side

1.12 1.10

1.2

1.06

1.00

1.00 1.14

1.3

air side

wheel side

1.06

1.08 1.04

1.06 1.1

1.04

1.02

1.02

0.9

0.8

x = 12

relative transmission

1.00 1.00

relative transmission

relative transmission

1.0 1.0

0.95

x = 15

1.00 1.00 0.98 0.96 0.94 0.92

x = 17

0.90 -5

0

velocity (mm/s)

5

-5

0

velocity (mm/s)

5

-5

0

velocity (mm/s)

5

CEMS: Onset of Crystallization l M. Miglierini et al. Phys. Met. Met 104 (2007) 335-345

0

velocity (mm/s)

5

wheel side a.q.

air side Tx1 = 410 °C

a.q. o 330o C 370 C o 410o C 430o C 450o C 470o C 490o C 510o C 530 C

0.1%

-5

Fe79Mo8Cu1B12

a.q. o 330o C 370 C o 410o C 430o C 450o C 470o C 490o C 510 C o 530 C

0.1%

-5

0

velocity (mm/s)

5

TMS: Onset of Crystallization l

Fe79Mo8Cu1B12

TMS Tx1 = 430 °C TMS CEMS air CEMS wheel

a.q. o 330o C 370o C 410o C 430 C o 450o C 470o C 490o C 510o C 530 C

10%

-5

0

velocity (mm/s)

5

relative area (%)

60

40

20

0 a.q.

300

400

500

annealing temperature (°C)

600

Nuclear Magnetic Resonance l as-quenched

Fe90Zr7B3 @ 300 K – no NMR signal l 4.2 K: broad signal à amorphous (domains) l

enriched 57Fe: narrow signal à single domain Fe particles (33.93 T) (domains) 57Fe Mössbauer Spectroscopy 57Fe NMR 1.00

80 60 40 20 0

4.2 K

0.2 0.98

P(B)

relative transmission

relative intensity

100

0.1

0.96

0.94

4.2 K 0.0

10

15

20

25

30

hyperfine field (T)

35

40

-10

-5

0

velocity (mm/s)

5

10

0

10

20

B (T)

30

40

NMR: Nanocrystalline Structure l

Fe90Zr7B3 l Ta = 620 oC l 4.2 K

1.5 0.99

P(B)

relative transmission

1.00

0.98

1.0

0.5 0.97 0.0 -5

0

5

0

10

velocity (mm/s)

domains

4 3 2

as-quenched o 510 C/10 min o 620 C/80 min

1 0

15

20

25

30

Bhf (MHz)

35

40

30

40

B (T)

5

(a) intensity (a.u.)

intensity (a.u.)

5

20

walls

(b)

4 3 2 1 0

15

20

25

30

Bhf (MHz)

35

40

Positron Annihilation Spectroscopy l

Fe76Mo8Cu1B15

l

coercive force (A/m)

lifetime (ps)

160

150

140

130

positron lifetime l structural relaxation l free volume 250 200 60 40 20 0

a.q.

300

400

500

600

700

o

annealing temperature ( C) M. Miglierini, et al.: J. Magn. Magn. Mat. 304 (2006) e666

a.q.

300

400

500

600

700

o

annealing temperature ( C) M. Miglierini et al., Czech. J. Phys. 54 (2004) D73

Summary scanning depth

surface < 200nm

technique

AFM, MFM CEMS

1 - 10μm

XRD, DSR

entire bulk

PAS, TMS, NMR

information derived

morphology and sizes, magnetic features structural arrangement, hyperfine interactions structural arrangement, in situ evolution of structure structural arrangement hyperfine interactions

Bhagavadgítá, ch.4, ver.5

Part III. Unconventional Methods Śri Bhagaván said:

Arjuna, you and I have passed through many births. I know them all, while you do not, O chastiser of foes.

“Modern” Trends

l

Utamaro Kitagawa (1753-1806) lThree Modern Beauties (∼1792-1793)

Hyperfine Splitting of Nuclear Levels 57Fe

Ehf ≈ 100 neV Γ ≈ 5 neV

Eγ ≈ 14.4 keV

Ehf ≈ 100 neV l

excitation by synchrotron radiation l l

All transitions are excited at the same time. The resultant time response is a coherent sum of the indivitual transitions (the amplitudes are added).

Mössbauer Spectrometry with SR

57Fe

14.4 keV

energy domain

time domain

Nuclear Resonant Scattering storage ring sample beam undulator

∆t

IC

HRM

NFS NIS

bunch clock measured data

NFS ∆t

fast electronics

∆t

E∆ = 0

NIS ∆t

E∆ = 0

∆t

E∆ < 0 time

time

E∆ > 0

relative energy

temperature of annealing

Nuclear Forward Scattering

l

Fe79Mo8Cu1B12 l

-5

0

velocity (mm/s)

5

ID22N, ESRF 40

60

80

100

time (ns)

120

140

NFS: Composition x=0.00

x (rel. Co content)

relative transmission

l

(Fe1-xCox)79Mo8Cu1B12

x=0.10

x=0.14

x=0.20

x=0.33

x=0.50

-5

0

velocity (mm/s)

5

50

100

time (ns)

150

Nuclear Inelastic Scattering l

Mössbauer spectrometry in ~km/s range Energy (meV) -80

0

40

80

0.0

0.8

1.6

6

Absorption (a.u.)

10

2.0

amorphous

1.5

(intercrystalline)

crystalline

1.0

5

10

4

10

3

10

2

0

10

5

mm/s â km/s

velocity (mm/s)

-1.6

-0.8

Velocity (km/s) 0.08 -1

-5

DOS (meV )

relative emission

2.5

-40

Density of vibrational states:

0.06 0.04 0.02 0.00 0

10

20 30 Energy (meV)

40

complete characterization of elastic properties, dynamics, and thermodynamics

Nuclear Inelastic Scattering Stankov S., Yue Y. Z., Miglierini M., Sepiol B., Sergueev I., Chumakov A. I., Hu L., Švec P. and Rüffer R.: Phys. Rev. Let. 100 (2008) 235503

Fe90Zr7B3

0.05

-1

)

0.06

g(E) (meV

l

0.04

α - Fe foil

bulk α-Fe D C B A as quenched

D - 893K / 80 min C - 783K / 30 min B - 783K / 10 min

0.03

A - 753K / 10 min

0.02

as-quenched

0.01 0.00

10

20

30

Energy (meV)

40

50

Instead of Conclusions à Outlook 1.

effect of temperature and external magnetic field l l

2.

surface analyses à modifications l l

3.

amorphous residual phase nanocrystals conversion electron Mössbauer spectrometry atomic force microscopy (magnetic force microscopy)

synchrotron radiation l l l

diffraction of synchrotron radiation nuclear forward scattering nuclear inelastic scattering

Acknowledgement l

Bratislava: l Milan Pavúk l Peter Švec l Dušan Janičkovič

l

Berlin: l Gerhard Schumacher l Ivo Zizak

l

Grenoble: l Marcin Zajac l Rudolf Rüffer

l

Olomouc: l Miroslav Mašláň l Radek Zbořil l Milan Vůjtek l Klára Šafářová

l

Brno: l Yvonna Jirásková

l

Prague: l Jaroslav Kohout l Adriana Lančok

Support from grants: VEGA 1/4011/07, VEGA 2/0157/08, APVV-0413-06, KAN 400100653, VZ 0021620834, MSM6198959218, RII 3-CT-2004-506008