Optical absorption spectra of P defects in vitreous silica

Giacomazzi, Luigi; Martin‐Samos, Layla; Alessi, A.; Valant, Matjaž; Gunturu, Krishna Chaitanya; Boukenter, Aziz; Ouerdane, Y.; Girard, Sylvain; Richard, Nicolas

doi:10.1364/ome.8.000385

Cited by 12 publications

(19 citation statements)

References 47 publications

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“…Eight model structures have been considered in the present investigation: The original pure silica model (Model S0) 50 , a silica model containing a [(O-) 3 P=O] 0 unit and a hydrogen passivated three-fold Si (Model M1) 46 , and the fully first-principles relaxed silica model containing a [(O-) 2 P(=O) 2 ] − unit (Model M2) where a penta-coordinated silicon is formed 46 . Furthermore we consider, mainly for the discussion of the localized modes of the stretching region 1000–1300 cm −1 (see Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore we consider, mainly for the discussion of the localized modes of the stretching region 1000–1300 cm −1 (see Supplementary Fig. S1), also the not-fully relaxed model M2 which represents the ideal situation of an “isolated” [(O-) 2 P(=O) 2 ] − unit embedded silica (Model M2-I) 46 . Next we consider a model containing a [(O-) 2 P(=O) 2 ] − unit connected to a tetrahedron (Model M3) by sharing a corner (i.e.…”

Section: Resultsmentioning

confidence: 99%

“…Finally we consider the case (Model M4) in which the [(O-) 2 P(=O) 2 ] − unit is connected on both sides by tetrahedra (Model M4). We also performed vibrational spectra calculations for the P-doped configuration 46 featuring a substitutional P Si atom, isoelectronic to silicon, i.e. forming a [(O-) 2 P(-O) 2 ] + unit.…”

Section: Resultsmentioning

confidence: 99%

“…S2). The initial configurations used for the relaxations of models M2 and M3 have been obtained by taking advantage of a previously generated silica model featuring an ideal [(O-) 2 P(=O) 2 ] − unit 46 .

Figure 1Ball and stick models of the structures investigated in this paper: ( a ) Model M1, ( b ) Model M2, ( c ) Model M3-A. By exchanging Si and P located at sites A,B one can recover the other configuration M3-B mentioned in the text.…”

Section: Resultsmentioning

confidence: 99%

“…In this work, in order to discuss the precursor models of the r-POHC, we performed first-principles calculations of the Raman spectrum for a few nm-size P-doped silica periodic models which allow for a proper description of the vibrational modes of silica glass. The present investigation, mainly based on a Raman spectra analysis, leads us to propose and validate an alternative precursor model of the r-POHC consisting of a structural unit made of (at least) two phosphate corner-sharing tetrahedra of which one is a [(O-) 2 P(=O) 2 ] − unit while the other a [(O-) 2 P(-O) 2 ] + unit 46 . In the present work we show that a corner-sharing phosphate model is able to well explain both the appearence of a band at ~1150 cm −1 in the Raman spectrum of P-doped silica, as well as the appearence of r-POHC centers in the irradiated glass.…”

Section: Introductionmentioning

confidence: 99%

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v-P2O5 micro-clustering in P-doped silica studied by a first-principles Raman investigation

Giacomazzi

Martin‐Samos

Alessi

et al. 2019

Sci Rep

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Synthetic vitreous silica is currently the preferred material for the production of optical fibres because of the several excellent properties of this glass, e.g. high transmission in the visible and IR domains, high mechanical strength, chemical durability, and ease of doping with various materials. For instance, fiber lasers and amplifiers exploit the light amplification properties provided by rare-earth ions employed as dopants in the core of silica-based optical fibers. The structure and composition of the nearest neighbor shell surrounding rare-earth ions in silica-based optical fibers and amplifiers have been intensively debated in the last decade. To reduce aggregation effects between rare-earth ions, co-dopants such as phosphorus and aluminium are added as structural modifiers; phosphorus-doping, in particular, has proved to be very efficient in dissolving rare-earth ions. In this work, we provide further insights concerning the embedding of P atoms into the silica network, which may be relevant for explaining the ease of formation of a phosphorus pentoxide nearest-neighbor shell around a rare-earth dopant. In particular, by means of first-principles calculations, we discuss alternative models for an irradiation (UV, x –, γ -rays) induced paramagnetic center, i.e. the so called room-temperature phosphorus-oxygen-hole center, and its precursors. We report that the most likely precursor of a room-temperature phosphorus-oxygen-hole center comprises of a micro-cluster of a few (at least two) neighboring phosphate tetrahedra, and correspondingly that the occurrence of isolated [(O-) 2 P(=O) 2 ] − units is unlikely even at low P-doping concentrations. In fact, this work predicts that the symmetric stretching of P=O bonds in isolated [(O-) 2 P(=O) 2 ] − units appears as a Raman band at a frequency of ~1110 cm −1 , and only by including at least another corner-sharing phosphate tetrahedron, it is shown to shift to higher frequencies (up to ~40 cm −1 ) due to the shortening of P=O bonds, thereby leading to an improved agreement with the observed Raman band located at ~1145 cm −1 .

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

v-P2O5 micro-clustering in P-doped silica studied by a first-principles Raman investigation

Giacomazzi

Martin‐Samos

Alessi

et al. 2019

Sci Rep

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On the Structure of Oxygen Deficient Amorphous Oxide Films

Strand,

Shluger

2023

Advanced Science

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Understanding defects in amorphous oxide films and heterostructures is vital to improving performance of microelectronic devices, thin‐film transistors, and electrocatalysis. However, to what extent the structure and properties of point defects in amorphous solids are similar to those in the crystalline phase are still debated. The validity of this analogy and the experimental and theoretical evidence of the effects of oxygen deficiency in amorphous oxide films are critically discussed. The authors start with the meaning and significance of defect models, such as “oxygen vacancy” in crystalline oxides, and then introduce experimental and computational methods used to study intrinsic defects in amorphous oxides and discuss their limitations and challenges. To test the validity of existing defect models, ab initio molecular dynamics is used with a non‐local density functional to model the structure and electronic properties of oxygen‐deficient amorphous alumina. Unlike some previous studies, the formation of deep defect states in the bandgap caused by the oxygen deficiency is found. Apart from atomistic structures analogous to crystal vacancies, the formation of more stable defect states characterized by the bond formation between under‐coordinated Al ions is shown. The limitations of such defect models and how they may be overcome in simulations are discussed.

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Effects of gamma radiation on Yb-doped Al–P–silicate optical fibers

et al. 2022

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Ytterbium (Yb)-doped optical fibers are mainly used in the fiber laser resonator and amplifier systems. These systems have been widely utilized for applications in air and space, the defense industry, and the medical field. Particularly for the applications yielding operation in harsh environments consisting of radiation, it is essential to determine the radiation hardness of the Yb-doped optical fibers and their long-term performance in such environments. This study analyzed the optical properties of four different Yb-doped aluminophosphosilicate fibers before and after gamma irradiation. For each fiber, the effect of different total dose values including 0.5, 1, 10, and 50 kGy were determined at different operation wavelengths, such as 495 nm, 590 nm, 685 nm, and 730 nm, using radiation-induced attenuation (RIA) analysing curves. The total dose values of 10 kGy and 50 kGy were studied to demonstrate the results under extreme environmental conditions such as large hadron colliders (LHCs). Our findings reveal that the formation of radiation-induced color centers (e.g. AlOHC, POHC, and NBOHC) are highly dependent on the Yb-concentration, the amount of excess alumina (Al 2 O 3 ) compared to the phosphorous pentoxide (P 2 O 5 ), total irradiation dose and wavelength at which the respective RIA is recorded.

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Optical absorption spectra of P defects in vitreous silica

Cited by 12 publications

References 47 publications

v-P2O5 micro-clustering in P-doped silica studied by a first-principles Raman investigation

v-P2O5 micro-clustering in P-doped silica studied by a first-principles Raman investigation

On the Structure of Oxygen Deficient Amorphous Oxide Films

Effects of gamma radiation on Yb-doped Al–P–silicate optical fibers

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