Length scales

HRTEM, PICO

SEM+EBSD, ESMA

Large Chamber SEM

Length scales

Micro sc opic Details

Å µm

mm

Structur, Defects

Microstructure, Phase Changes, Internal Strain

Full size parts, Technological

Behaviour

ELECTRON MICROSCOPY: SCALE BRIDGING ANALYSIS

Contributions of characterisation experiments

Conclusions on damage mechanisms

Structure/property relationships

Materials

modifications

Degradation, failure

Ion irradiation and energy dissipation

Diffusion and defect agglo- meration

High resolution

microstructure analysis

In situ experiments

Outline

• Degradation analysis of divertor elements

• In situ-TEM observations

• Aberration corrected TEM (Ernst Ruska-Centre)

• Applications to defect analysis

2.46 Å

Plasma facing components in ITER

J. Linke, A. Schmidt, FZ Jülich

?

VISITEC LC – SEM at RWTH Aachen University

• Variable pressure

• Peltier-cooled EDX (Noran)

• EBSD (HKL)

Monoblock

Heat flux up to 20 MW/m²

Flat tile

Heat flux < 5 MW/m²

Flat tile or monoblock

Heat flux < 5 MW/m²

W monoblocks

CFC monoblocks

VT Full-Scale Prototype

Plasma facing components in ITER: the divertor

Electron beam simulation of ITER relevant thermal loads

1 electron beam gun 2 vacuum chamber 3 cooling circuit 4 test component 5. diagnostics

Electron beam test facility JUDITH 2

P = 200 kW (30...60 keV) P/a  10 GWm^-2

fast scanning: 1.4° µs^-1

e-beam

fatigue testing: up to 20 MWm^-2 10 s on / 10 s off

typical beam mode for thermal fatigue test

Plasma facing components under cyclic thermal loads

critical area

flat tile design monoblock

W CFC

Thermal load during ELMS:  2 GWm

, t = 500 µs

 high cycle thermal fatigue

W- tiles

High Cycle Thermal Fatique

3-D carbon fiber composite

PAN-fibers

pitch-fibers needled PAN-fibers

Z

Y

X

high thermal conductivity

CFC-Tiles

W-deposits interlaminar

cracks

Surface Erosion

Contributions of characterisation experiments

Conclusions on damage mechanisms

Structure/property relationships

Materials

modifications

Degradation, failure

Ion irradiation and energy dissipation

Diffusion and defect agglo- meration

High resolution

microstructure analysis

In situ experiments

In situ-experiments (Robin Schäublin)

In situ-Transmission electron microscopy: study of radiation induced damage in real time, direct imaging of induced microstructural features, down to the atomic level.

In addition, TEM in situ irradiation experiments allow to see damage creation dynamically, as in the JANNuS facility in Orsay, France, with dual beam:

IRRADIATION FACILITY FOR IN SITU: JANNUS ORSAY

IRMA

ARAMIS

e^-

• In situ dual beam allows the study of the impact of damage + gases

Irradiation induced damage in Tungsten

Irradiation conditions

JANNuS facility of CSNSM, University Paris Sud, Orsay, France Ion irradiation in situ in a TEM FEI Tecnai G2 200 kV

Ion accelerator used : ARAMIS Energy and ion: 1.2 MeV W⁺ ions

Total dose : 1.8·10¹² ions, corresponding to 0.017 dpa Irradiation time : 10 minutes

Temperature : 700°C

First minute:

(movie, real time)

• Impact from single cascades is visible from the start

• Limited mobility of defects (Contrary to Fe)

R. Schäublin, M. Sidibe, B. Décamps, M.-F. Barthe 2014

Irradiation induced damage in Tungsten

1.2 MeV W⁺ ions, 700°C, 0.017 dpa, using bright field TEM imaging, 200 kV, g{200}

• Irradiation induced damage consists mainly in dislocation loops

• Dislocation loops agglomerate in rafts elongated along <100>

• Scattered individual loops • Difficult to image thick areas for W has high Z ! R. Schäublin, B. Décamps, M.-F. Barthe 2014

Irradiation induced damage in Tungsten

• BF STEM imaging, to avoid inelastic electrons blurring the image;

allows thicker areas to be investigated

• Tilt series, from -35 ° to +35 °

3D reconstruction of the dislocation loops distribution

1.2 MeV W⁺  W 700°C 0.017 dpa

W⁺

S. Hasanzadeh, E. Oveisi, C. Hébert, B. Décamps, M.-F. Barthe, R. Schäublin 2015 (movie)

Irradiation induced defects in Fe(Cr) alloys

JANNuS experiment

Single beam Fe 300 KeV, from 0.12 to 1 dpa, RT, on UHP Fe Movie accelerated 50x

TEM observation condition 200 kV WBDF g(4g) g(110)

• ½ a0<111> loops, highly mobile

B. Décamps, O. Kaïtasov, E. Oliviero, C. Baumier, C. Bachelet, CNRS Orsay

Experiments performed on ultra high purity ferritic materials in view of validating modelling of radiation damage

A. Prokhodtseva a, B. Décamps and R. Schäublin, Journal of Nuclear Materials 442 (2013) S786–S789

effect of He on irradiated UHP Fe(Cr) at RT using JANNuS dual beam

0.5 dpa RT 0.5 dpa + 1000 appm He RT

Thickness: 100 nm

Defect density: 2.8·10²² m^-3

Burgers vector: a₀<100> 96%

½ a₀<111> 4%

Thickness: 120 nm

Defect density: 5.0·10²² m^-3

Burgers vector: a₀<100> <1%

½ a₀<111> 99%

g =110 g =110

Irradiation induced defects in Fe(Cr) alloys

• Stat. method allows telling with confidence that black dots are mainly a₀<100> loops

• When He is co-implanted: more black dots, mainly ½ a₀<111> loops ^ He pins loops

• Primary damage is made of ½ a₀<111> loops, a₀<100> come from their interaction

A. Prokhodtseva, B. Décamps and R. Schäublin, Journal of Nuclear Materials 442 (2013) S786–S789

effect of He on irradiated UHP Fe(Cr) at 500°C using JANNuS dual beam

Irradiation induced defects in Fe(Cr) alloys

• a₀<100> dislocation loops, mobile along <100>

• He reduces mobility of <100> loops, nucleation of cavities on dislocation cores

D. Brimbal, E. Meslin, J. Henry, B. Décamps, A. Barbu, Acta Materialia 61 (2013) 4757–4764

Bright field, g=(110) (s>>0), underfoc.:-5,9µm Bright field, g=(110) (s>>0), overfoc.:+5,9µm

Ernst Ruska-Centre for

Microscopy and Spectroscopy

with Electrons

m

mm

nm µm

Å Hair

Light Transistor

Atom

Comparison of

Resolution Limits of Optical Instruments

Electron wavelength pm

100 x

100 x

Spherical Aberration

Magnetic Lens

Gaussian Image Plane Phase-Shift

500 correctors for

spherical aberration

installed worldwide

Chromatic Aberration

two correctors for

chromatic aberration

(HRTEM) installed

worldwide

FEI TITAN 80 – 300 (2006)

PICO (2011)

Cs-corrected protoype

Cs-corrected

Cs/Cc-corr.

Rose, Haider, Urban (1998)

Three generations of

aberration corrected HRTEMs

Chromatic Aberration

E 

C dE d _{c c}

2

 1

Biggest impact of Cc-correction expected for:

• large energy spread dE (EFTEM)

• low accelerating voltages (low E)

PICO resolution

Fourier transform of C

and C

correct

Sub-Ångstrøm resolution at 80 kV

Resolution improvement to 0.8 Å due to C

-correction

0.5 nm

L. Houben

Few- layer hexagon

al boron nitride viewed along c-

axis Haider et al, Ultramicroscopy

108 (2008) 167

PICO: atomic resolution at 50 kV

Graphene:Pd

inverted positive phase contrast

2 nm

2.46 Å

Pd

9.37 nm^-1

sample courtesy of U.Bangert, University of Manchester

9.8 nm^-1

Au/C

1 Å

Lothar Houben (ER-C)

Catalytic Rh-Nanoparticles in Ionic Liquid on Graphene

J. Barthel (ER-C), M. Marquardt (Univ. Düsseldorf) Case study

PICO,

U = 80 kV

V or I R

Resistive switching

Metal Insulator Metal

Phase I: 2011––2015 Phase II: 2015––2019

Non-Volatile Memories

DFG - Deutsche Forschungsgemeinschaft

interface substrate

film

a) b)

Overview of the Fe-doped SrTiO ₃ films

SrTi_0.95Fe_0.05O₃ films grown on <001>-oriented 1.0% Nb-doped SrTiO₃ substrates (Crystec. Berlin) by pulsed laser deposition (PLD)

cross-section [100] plan view [001]

BF-TEM by Titan-T@300kV 100nm

Defect Loops: Plan View [001]

1

2 3

a) b)

x O

y

z

( 0k0 ) h 0

0 ) (

t

type 2:

y p t e 1

:

Translation vector t is a/2[011]

Two types of APBs lie on {100}

planes depending whether they parallel t (APB1) or not (APB2)

Type 1 APB a)

anatase

Sr Ti O

APB1

b)

Atomic Structure of APBs

b) a)

Sr Ti O

Type 2 APB Type 3 APB

Du H, Jia C-L, Mayer J, Barthel J, Lenser C, Dittmann R. Adv. Funct.

Mater. 2015, DOI:10.1002/adfm.201500852

Atomically resolved EDX spectrum imaging

a

f c

d e

b

Sr Ti Fe

O Sr+Ti+Fe Sr+Ti+Fe + HAADF

Fe shows enrichment at APBs.

Dislocations at SrTiO

low-angle tilt bicrystals grain boundary

b (Burgers vector)

Frank’s Formula

grain boundary

• Controllable type and density of dislocations.

• Model system for in-depth

study of the relationship

between structure and

property.

Core Structure

a) b)

e) f)

y x Sr Ti O

x z y

c) d)

3 1 2

1 nm HAADF PICO@80 kV

a＝0.42 nm

a＝0.39 nm

FCC TiO

EDX spectrum imaging @200 kV

a)! b)! c)! d)! e)! f)!

1 nm!

Sr Ti Sr+Ti HAADF (51) HAADF+Sr+Ti

Extra Peaks @ tensional strain side

SrTiO

a=0.39nm

TiO

a=0.42nm

Sr Ti O

compression

tension

ε

Energy loss near edge fine structure

δ estimated by the free carrier density (Hall effect) ––––Ref. D. A Muller et al. Nature v430,p657.

Ti L_2,3 (2p–>3d) O K (1s–>2p)

SrTiO_3–δ

δ=0.25 δ=0 Core Bulk t_2g e_g

e_g

t_2g C

A B

Valence/Bonding state mapping

Reduction of Ti-valency state makes dislocation

core electrically active!

Summary: dislocations in SrTiO ₃

• Edge-sharing TiO

octahedra associated with the FCC TiO phase at the tensional side of the dislocation cores.

• Result of strain energy (lattice constant of FCC TiO: 0.42 nm, SrTiO

: 0.39 nm).

• Reduction of Ti-valency state makes dislocation core electrically active.

SrTiO₃ a=0.39nm

FCC TiO a=0.42nm

Sr Ti O

x y

compression

tension ε_xx

H. Du, C.-L. Jia, L. Houben, V. Metlenko, R.A. De Souza, R. Waser, J. Mayer, Acta Materialia. 89 (2015) 344–351. doi:10.1016/j.actamat.2015.02.016.

Ti