SEWG Meeting Mixed Materials 2007 First results from beryllium on carbon Florian Kost Christian 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 of ternary systems Approach: bottom-up

SEWG Meeting Mixed Materials 2007 C Be The binary system + C substrateBe 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 C carbide formation during evaporation Be Preparation

SEWG Meeting Mixed Materials 2007 C Be 970 K Preparation

SEWG Meeting Mixed Materials 2007 E 1s E Vak EFEF E kin XPS principle 1486 eV

SEWG Meeting Mixed Materials 2007 Be1s Analysing XPS spectra

SEWG Meeting Mixed Materials 2007 alloy Be1s Analysing XPS spectra

SEWG Meeting Mixed Materials 2007 alloy metal Be1s Analysing XPS spectra

SEWG Meeting Mixed Materials 2007 alloy metal oxide 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 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 C amount: C/Be: sample composition

SEWG Meeting Mixed Materials 2007 C/Be: Summary Interface thin Be 2 C ( ) layer at RT, island structure? RT: Be 2 C limited to interface, additional C elementary Reaction first additional Be 2 C after 473K, lower than literature full Be 2 C formation: (673-) 773K, coverage dependent indications against layer growth (Be visible!) graphitic/disordered carbon: disordered Be 2 C or disordered graphitic Be 2 C

SEWG Meeting Mixed Materials 2007 The binary system C – Be Be/C

SEWG Meeting Mixed Materials 2007 Be 1s metallic C amount: C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007 Be 1s metallic C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007 Be 1s metallic C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007 Be 1s metallic carbidic C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007 Be 1s metallic carbidic C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007 Be 1s metallic carbidic C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007 Be 1s metallic carbidic C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007 Be 1s metallic carbidic C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007 Be 1s metallic carbidic C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007 Be 1sC 1s metallicgraphitic carbidic disordered C/Be: annealing experiments

SEWG Meeting Mixed Materials 2007 Be 1sC 1s metallicgraphitic carbidic disordered Increasing intensity C graph 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 C amount: ratio C graph / C dis const. Be/C: Results

SEWG Meeting Mixed Materials 2007 Possible reasons for BE-Shift: Growth/Shrinking of islands 970 K C C Be/C: binding energy shift

SEWG Meeting Mixed Materials 2007 Possible reasons for BE-Shift: Island charge effects isolating Be 2 C 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 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/CC/Be thin Be 2 C layer at RT, island structure? RT: Be 2 C limited to interface first additional Be 2 C after 773 K full Be 2 C formation: 773 K indications for island growth: graphitic C peak increasing carbide peak shifting graphitic/disordered carbon: disordered Be 2 C and graphitic Be 2 C first additional Be 2 C after 473 K, lower than literature full Be 2 C formation: (673-) 773 K, coverage dependent indications for island growth (Be visible!) graphitic/disordered carbon: disordered Be 2 C or disordered graphitic Be 2 C 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.