Identification of BeO and BeOxDy in melted zones of the JET Be limiter tiles: Raman study using comparison with laboratory samples

Kumar, Mohit; Sundén, E. Andersson; Binda, Federico; Cecconello, M.; Conroy, S.; Dzysiuk, N.; Ericsson, Göran; Eriksson, J.; Hellesen, C.; Hjalmarsson, Anders; Possnert, Göran; Sjöstrand, Henrik; Skiba, Mateusz; Weiszflog, M.; Zychor, I.

doi:10.1016/j.nme.2018.11.008

Cited by 21 publications

(20 citation statements)

References 32 publications

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“…This technique is based on an inelastic light scattering process and is highly sensitive to chemical composition, structure and morphology. Depending on the optical constants of the probed material, Raman microscopy can be sensitive to the near surface (few tens of nanometers in the case of metals) with a micrometer lateral resolution, that allows monitoring spatial inhomogeneities [11,12].…”

Section: Introductionmentioning

confidence: 99%

Post-mortem analysis of tungsten plasma facing components in tokamaks: Raman microscopy measurements on compact, porous oxide and nitride films and nanoparticles

Pardanaud¹,

Dellasega²,

Passoni³

et al. 2020

Nucl. Fusion

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Raman microscopy is one of the methods that could be used for future post-mortem analyses of samples extracted from ITER plasma facing. This study shows that this technique is useful for studying tungsten-based materials containing impurities including oxides and nitrides. Here, we apply pulsed laser deposition and DC argon glow discharges to produce tungsten-containing synthetic films (compact, porous) and nanoparticles and investigate the influence of their morphology on the measured Raman spectra. The amounts of oxygen and/or nitrogen in the films are also investigated. Comparative data are obtained by X-ray Photoelectrons Spectroscopy, Atomic Force Microscopy, Electron Microscopies (Scanning and Transmission), Energy Dispersive X-ray spectroscopy, Time-of-Flight Elastic Recoil Detection Analysis. The power density of the laser beam used to perform Raman microscopy is varied by up to 4 orders of magnitude (0.01-20 mW/μm 2 ) to investigate thermal stability of films and nanoparticles. As a first result, we give evidence that Raman microscopy is sensitive enough to detect surface native oxides. Secondly, more tungsten oxides are detected in porous materials and nanoparticles than in compact films, and the intensities of the Raman band correlate to their oxygen content. Thirdly, thermal stability of these films (i.e. structural and chemical modification under laser heating) is poor when compact films contain a sufficiently large amount of nitrogen. This finding suggests that nitrogen can be substituted by oxygen during Raman laser induced heating occurring in ambient air. Finally, our methodology can be used to rapidly characterize morphology and chemistry of the samples analyzed, and also to create oxides at the micrometer scale.

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Section: Introductionmentioning

confidence: 99%

Post-mortem analysis of tungsten plasma facing components in tokamaks: Raman microscopy measurements on compact, porous oxide and nitride films and nanoparticles

Pardanaud¹,

Dellasega²,

Passoni³

et al. 2020

Nucl. Fusion

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“…This band is associated with bondorder and bond-length defects, and in this case, excitation of such phonon is contributed by PDOS. 17,20 This mode does not belong to the excitation of the fundamental E 2g mode of the ordered Be−Be bonding. However, the scattered energy of this band exists in the optical phonon region, and therefore we designate it as a transverse optical (TO) band of amorphous Be (a-Be) phase.…”

Section: Resultsmentioning

confidence: 97%

“…However, several other phonon bands may also be excited, which is originated by phonon density of state (PDOS) and defects. 17 effect at the Be(0001) surface. 21 This coupling may induce a possible effect on phonon excitation using Raman scattering.…”

Section: Introductionmentioning

confidence: 99%

“…The B 1g and E 2g belong to longitudinal and transverse optical modes, respectively, and only doubly degenerate E 2g mode is Raman-active. However, several other phonon bands may also be excited, which is originated by phonon density of state (PDOS) and defects. − The Be is a semimetal, which has shown a large electron–phonon coupling effect at the Be(0001) surface . This coupling may induce a possible effect on phonon excitation using Raman scattering.…”

Section: Introductionmentioning

confidence: 99%

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Microstructural Transformation of Nanoscale Be Layers in the Mo/Be and Be/Mo Periodic Multilayer Mirrors Investigated by Raman Spectroscopy

et al. 2021

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Raman scattering studies were carried out for the investigation of bonding and microstructural properties of dimensionally confined nanoscale Be layers in the periodic Mo/Be and Be/Mo multilayer structures. The amorphous phase of alternate periodic Be nanolayers was partially transformed into the crystalline phase at the critical thickness of 2.44 nm. Crystallinity was further improved with the increase in the thickness of the periodic Be layers, which was associated with the decline of the surface-to-volume ratio of Be–Be bonding. However, upon thermal annealing, the bond-order defects in the crystalline Be phase gradually increased due to thermal stretching of Be–Be bonding. Beyond the critical annealing temperature of 573 K, a complete transformation of crystalline to ultrashort-ranged amorphous Be phase was observed in the multilayer structures. At critical thicknesses, the transformation of amorphous Mo and Be nanolayers into the polycrystalline structure was confirmed by the combination of X-ray diffraction and Raman scattering studies, respectively.

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“…BeO can also be formed during offnormal events like melting of Be, as BeO inclusions have been observed by Raman spectroscopy in melted regions [6,7]. The sputtering of BeO by deuterium (D) ions is thus of importance for the description and understanding of the plasma-wall interactions.…”

Section: Introductionmentioning

confidence: 99%

Sputtering of beryllium oxide by deuterium at various temperatures simulated with molecular dynamics

Hodille¹,

Byggmästar²,

Safi³

et al. 2020

Phys. Scr.

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The sputtering yield of beryllium oxide (BeO) by incident deuterium (D) ions, for energies from 10 eV to 200 eV, has been calculated for temperatures between 300 K and 800 K using classical molecular dynamics. First, cumulative irradiations are done to build up a concentration of D in the material, equal to the one experimentally measured, that varies from 0.12 atomic fraction (300 K -500 K) to 0.02 atomic fraction (800 K). After building up the concentration of D, non-cumulative irradiations are done to estimate the sputtering yields of BeO. For all incident energies, the sputtering yield peaks at 500 K, being closely related to the decrease of the concentration of D above this temperature. While for 10 eV, the concentration of D on the surface drives the temperature dependence, above 30 eV, it is the amount of surface damage created during the cumulative irradiation.

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Identification of BeO and BeOxDy in melted zones of the JET Be limiter tiles: Raman study using comparison with laboratory samples

Cited by 21 publications

References 32 publications

Post-mortem analysis of tungsten plasma facing components in tokamaks: Raman microscopy measurements on compact, porous oxide and nitride films and nanoparticles

Post-mortem analysis of tungsten plasma facing components in tokamaks: Raman microscopy measurements on compact, porous oxide and nitride films and nanoparticles

Microstructural Transformation of Nanoscale Be Layers in the Mo/Be and Be/Mo Periodic Multilayer Mirrors Investigated by Raman Spectroscopy

Sputtering of beryllium oxide by deuterium at various temperatures simulated with molecular dynamics

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