Anharmonic interactions in beryllium oxide

Morell, Gerardo; Pérez, W.; Ching-Prado, E.; Rs, Katiyar

doi:10.1103/physrevb.53.5388

Cited by 39 publications

(28 citation statements)

References 30 publications

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“…The vibrational frequencies can also be computed by DFT, which complements the Raman analysis. Raman microscopy is a nondestructive, non-contact, and local (≈1m 2 lateral resolution [23]) technique that has been proved to be sensitive to Be stretching modes [24], beryllium oxide modes [25], bending and stretching tungsten oxide modes [26], Be x W y mixed samples density of states [27], Be-C-W irradiated samples [28], and give information when a pristine material is implanted by hydrogen ions [27,29,30]. First Raman analyses in ILW-tokamaks were performed on several molybdenum JET mirrors [27], showing that the technique is sensitive to thin (≈10 nm) deposited layer composed of ≈33% Be, ≈33% C and ≈33% O and to the underlying molybdenum oxidized mirror, the atomic percent being obtained by X-ray Photon spectroscopy (XPS).…”

Section: Introductionmentioning

confidence: 99%

Preparing the future post-mortem analysis of beryllium-based JET and ITER samples by multi-wavelengths Raman spectroscopy on implanted Be, and co-deposited Be

et al. 2017

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This study demonstrates that Raman microscopy is a suitable technique for future post mortem analyses of JET and ITER plasma facing components. We focus here on laboratory deposited and bombarded samples of beryllium and beryllium carbides and start to build a reference spectral databases for fusion relevant beryllium-based materials. We identified the beryllium phonon density of states, its second harmonic and E 2G and B 2G second harmonic and combination modes for defective beryllium in the spectral range 300-700 and 700-1300 cm -1 , lying close to Be-D modes of beryllium hydrides. We also identified beryllium carbide signature, Be 2 C, combining Raman microscopy and DFT calculation. We have shown that, depending on the optical constants of the material probed, in depth sensitivity at the nanometer scale can be performed using different wavelengths. This way, we demonstrate that multi-wavelength Raman microscopy is sensitive to in-depth stress caused by ion implantation (down to ≈30 nm under the surface for Be) and Be/C concentration (down to 400 nm or more under the surface for Be+C), which is a main contribution of this work. The depth resolution reached can then be adapted for studying the supersaturated surface layer found on tokamak deposits.2

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Section: Introductionmentioning

confidence: 99%

Preparing the future post-mortem analysis of beryllium-based JET and ITER samples by multi-wavelengths Raman spectroscopy on implanted Be, and co-deposited Be

et al. 2017

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“…The information on the lattice dynamics of BeO is limited to Raman [3][4][5][6][7] and IR-absorption 3 studies, and inelasticneutron-scattering ͑INS͒ data for selected low-lying phonon branches. 8,9 The first INS study showed the presence of a nearly flat branch 9 at low energy not observed in a subsequent experiment.…”

Section: Introductionmentioning

confidence: 99%

Lattice dynamics of beryllium oxide: Inelastic x-ray scattering andab initiocalculations

Bosak

Schmalzl²,

Krisch

et al. 2008

Phys. Rev. B

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The phonon-dispersion relations of the lightest wurtzite structure compound BeO have been determined from inelastic x-ray scattering ͑IXS͒ measurements and analyzed by ab initio calculations. Experimental data and calculations show good agreement and reconcile the existing controversies. The phonon linewidth of the longitudinal-optical phonon along ⌫-A reveals a marked q dependence, which can be correlated with the two-phonon density of states, thus pointing toward a strong anharmonic behavior.

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“…TiO 2 in anatase phase has six first-order Raman active modes among which low frequency E g (1) and E g(2) modes exhibit frequency shift up (hardening behavior) with increasing temperature while the other four modes exhibit softening behavior with rising temperature [24][25][26]. In Fig.…”

Section: Intrinsic Anharmonicity In Nanocrystalline Anatase Tiomentioning

confidence: 99%

“…The Raman spectra of various amorphous or crystalline materials show changes in line position and bandwidth with temperature [1][2][3][4]. This changes manifest in shift of line position and a change in line width and intensity.…”

Section: Introductionmentioning

confidence: 99%

Anharmonicity Effects in Nanocrystals Studied by Raman Scattering Spectroscopy

Dohčević‐Mitrović

Popović²,

Šćepanović³

2009

Acta Phys. Pol. A

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Phonon-phonon interactions were investigated in various nanocrystalline powders like anatase TiO 2−δ , pure CeO 2−δ and ceria doped with Nd(Gd) analyzing temperature dependent Raman spectra of these systems. Phonon confinement model based on size, inhomogeneous strain and anharmonic effects was used to properly describe the evident changes present in the Raman spectra of pure and doped ceria nanocrystalline samples. In small particles of pure and doped ceria nanocrystals, when size effects have minor impact on Raman modes, four phonon anharmonic processes prevail under the three-phonon ones. When nanopowdered particles are grown enough size effects provoke changes of the anharmonic interactions when three-phonon coupling prevails over the four-phonon anharmonic processes. In nanocrystalline anatase TiO 2 evident blueshift of the most prominent E g Raman mode probably originates from dominant four-phonon anharmonic interactions.

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Anharmonic interactions in beryllium oxide

Cited by 39 publications

References 30 publications

Preparing the future post-mortem analysis of beryllium-based JET and ITER samples by multi-wavelengths Raman spectroscopy on implanted Be, and co-deposited Be

Preparing the future post-mortem analysis of beryllium-based JET and ITER samples by multi-wavelengths Raman spectroscopy on implanted Be, and co-deposited Be

Lattice dynamics of beryllium oxide: Inelastic x-ray scattering andab initiocalculations

Anharmonicity Effects in Nanocrystals Studied by Raman Scattering Spectroscopy

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