SEWG Meeting Mixed Materials 2007 First results from beryllium on carbon Florian Kost Christian...

SEWG Meeting Mixed Materials 2007

First results fromberyllium on carbon

Florian KostChristian Linsmeier

SEWG Meeting Mixed Materials 2007

The binary system C/Be

First results on Be/C

Future plans

Introduction • XPS system• preparation• analysis

Overview

• coverage variation experiments• annealing experiments• results

• annealing experiments• results

SEWG Meeting Mixed Materials 2007

The binary system

Aim: Understandig of the interaction beryllium – carbon – tungsten (ITER)

Understanding of binary systems

Understanding ofternary systems

Approach: „bottom-up“

SEWG Meeting Mixed Materials 2007

CBe

The binary system

+

C substrate Be substrate

not yet investigated

SEWG Meeting Mixed Materials 2007

XPS apparatus

SEWG Meeting Mixed Materials 2007

substrate

evaporation

Preparation

crucible

C

Be

SEWG Meeting Mixed Materials 2007

Ccarbide formationduring evaporation

Be

Preparation

SEWG Meeting Mixed Materials 2007

CBe

970 K

Preparation

SEWG Meeting Mixed Materials 2007

hkinE

ABkin EhE

E1s

EVak

EF

Ekin

h

S

XPS principle

1486 eV

SEWG Meeting Mixed Materials 2007

Be1s

Analysing XPS spectra

SEWG Meeting Mixed Materials 2007

alloyBe1s

Analysing XPS spectra

SEWG Meeting Mixed Materials 2007

alloy

metal

Be1s

Analysing XPS spectra

SEWG Meeting Mixed Materials 2007

alloy

metaloxide

Be1s

Analysing XPS spectra

SEWG Meeting Mixed Materials 2007

XPS information

• quantities of components surface composition

• chemical states (elements, oxides, carbides, alloys)

• sputter depth profiles

XPS depth of information: ML…nm

XPS measurements

SEWG Meeting Mixed Materials 2007

The binary system C – Be

C/Be(P. Goldstraß)

SEWG Meeting Mixed Materials 2007

Be

C

Be

C

…

XPS

C/Be: coverage variation experiments

SEWG Meeting Mixed Materials 2007

C/Au

SEWG Meeting Mixed Materials 2007

C/Be: coverage variation experiments

SEWG Meeting Mixed Materials 2007

C/Be: coverage variation experiments

SEWG Meeting Mixed Materials 2007

C/Be: coverage variation experiments

SEWG Meeting Mixed Materials 2007

C/Be: coverage variation experiments

SEWG Meeting Mixed Materials 2007

C/Be: coverage variation experiments

SEWG Meeting Mixed Materials 2007

C/Be: coverage variation experiments

SEWG Meeting Mixed Materials 2007

C/Be: coverage variation experiments

SEWG Meeting Mixed Materials 2007

C/Be: binding energy shift

SEWG Meeting Mixed Materials 2007

Be

C …XPS

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

C/Be: sample composition

SEWG Meeting Mixed Materials 2007

Two possible reactions:

Transition disordered graphite

Transition disordered carbide

C/Be: sample composition

SEWG Meeting Mixed Materials 2007

-215cm104~ -216cm105~ C amount:

C/Be: sample composition

SEWG Meeting Mixed Materials 2007

C/Be: SummaryInterface• thin Be2C ( ) layer at RT, island structure?• RT: Be2C limited to interface, additional C elementary

Reaction • first additional Be2C after 473K, lower than literature

• full Be2C formation: (673-) 773K, coverage dependent• indications against layer growth (Be visible!)• graphitic/disordered carbon:

disordered Be2C or disordered graphitic Be2C

ML6cmC106 215

SEWG Meeting Mixed Materials 2007

The binary system C – Be

Be/C

SEWG Meeting Mixed Materials 2007

Be 1smetallic

-216cm105~ C amount:

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

Be 1smetallic

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

Be 1smetallic

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

Be 1smetalliccarbidic

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

Be 1smetalliccarbidic

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

Be 1smetalliccarbidic

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

Be 1smetalliccarbidic

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

Be 1smetalliccarbidic

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

Be 1smetalliccarbidic

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

Be 1s C 1smetallic graphitic

carbidic

carbidicdisordered

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

Be 1s C 1smetallic graphitic

carbidic

carbidicdisordered

Increasing intensity Cgraph

► Substrate visible► Hint to island growth

C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007

C 1s binding energies C 1s elemental composition

Be/C: Results

770 K

SEWG Meeting Mixed Materials 2007

-216cm105~ C amount:

200 400 600 800 1000 1200 14000

10

20

30

40

50

60

70

80

90

100

C 1

s co

mp

osi

tio

n [

%]

temperature [K]

Be2C

Cgraph

Cdiss

ratio

Cgraph / Cdis

const.

Be/C: Results

SEWG Meeting Mixed Materials 2007

Possible reasons for BE-Shift:

• Growth/Shrinking of islands

970 K CC

Be/C: binding energy shift

SEWG Meeting Mixed Materials 2007

Possible reasons for BE-Shift:

• Island charge effects

isolatingBe2C islands

++

C

Be/C: binding energy shift

SEWG Meeting Mixed Materials 2007

Possible reasons for BE-Shift:

• Influence of oxygen: Be – O – C compound

970 K

+ O

Be/C: binding energy shift

SEWG Meeting Mixed Materials 2007

1070 K

Possible reasons for BE-Shift:

• Two different peaks

1170 K

Be/C: binding energy shift

SEWG Meeting Mixed Materials 2007

Possible reasons for BE-Shift:

• Two different peaks

1070 K 1170 K

Be/C: binding energy shift

SEWG Meeting Mixed Materials 2007

Possible reasons for BE-Shift:

• Two different peaks

1070 K 1170 K

Be/C: binding energy shift

SEWG Meeting Mixed Materials 2007

Be/C C/Be• thin Be2C layer at RT, island structure?

• RT: Be2C limited to interface

• first additional Be2C after 773 K

• full Be2C formation: 773 K

• indications for island growth: graphitic C peak increasing carbide peak shifting

• graphitic/disordered carbon:

disordered Be2C and

graphitic Be2C

• first additional Be2C after 473 K, lower than literature

• full Be2C formation: (673-) 773 K, coverage dependent

• indications for island growth (Be visible!)• graphitic/disordered carbon:

disordered Be2C or

disordered graphitic Be2C

Summary

SEWG Meeting Mixed Materials 2007

Future plans

SEWG Meeting Mixed Materials 2007

Future plans

• AFM measurements• coverage variation experiments

(different thicknesses at RT)• Modifying substrate• Measurements at BESSY

Open questions:

Be/C• Reactions and compounds in Be/C (Diffusion, Desorption, Size

Effects ….)

• Influence of Be layer thickness

• Actual reason for shifting binding energy

• Influence of substrate (pyrolytic/amorphous carbon)

• Surface morphology

SEWG Meeting Mixed Materials 2007

Thank you.