A neutron diffraction investigation of the structure of vitreous boron trioxide

Johnson, Peter A.; Wright, Adrian C.; Sinclair, Roger N.

doi:10.1016/0022-3093(82)90092-8

Cited by 179 publications

(74 citation statements)

References 65 publications

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“…are well defined, as seen from neutron diffraction 13 and simulations 16 results. The angular distribution of the O-B-O bonds is 120…”

Section: The Structural Modelmentioning

confidence: 67%

“…For this reason, observing vibrations in the crystal would be of very limited guidance to assign the vibrations in the glass. The existence of boroxol rings in the glass is known from x-ray diffraction 10 , NMR 11 , RS 12 , and neutron scattering 13 . Although boroxols result from the bonding of three BO 3 triangles, these ESUs are special in that their internal B-O-B angle is ∼ = 120…”

Section: Introductionmentioning

confidence: 99%

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Hyper-Raman scattering analysis of the vibrations in vitreous boron oxide

et al. 2007

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Hyper-Raman scattering has been measured on vitreous boron oxide, v−B2O3. This spectroscopy, complemented with Raman scattering and infrared absorption, reveals the full set of vibrations that can be observed with light. A mode analysis is performed based on the local D 3h symmetry of BO3 triangles and B3O3 boroxol rings. The results show that in v−B2O3 the main spectral components can be succesfully assigned using this relatively simple model. In particular, it can be shown that the hyper-Raman boson peak arises from external modes that correspond mainly to librational motions of rigid boroxol rings.

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“…are well defined, as seen from neutron diffraction 13 and simulations 16 results. The angular distribution of the O-B-O bonds is 120…”

Section: The Structural Modelmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Hyper-Raman scattering analysis of the vibrations in vitreous boron oxide

et al. 2007

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“…The most remarkable difference between both sets of results regards the somewhat narrower shape of peaks in the elastic, and to a far lesser extent in the static, quantities at high temperature, as well as the noticeable departure of the static quantity from the one measured using total scattering ͑diffraction͒ techniques. 17 The counterintuitive result of peaks in S(Q,Eϭ0) becoming narrower as the temperature increases is also borne out by results calculated by computer simulation as data plotted in Fig. 2 demonstrates.…”

Section: A Structure Factorsmentioning

confidence: 94%

Anomalous temperature dependence of the first diffraction peak in vitreous boron trioxide

et al. 1996

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The temperature dependence of the parameters characterizing the first peak in the S(Q) and S(Q,Eϭ0) diffraction patterns of vitreous boron trioxide is considered in some detail. The analysis of the experimental spectra is aided by results derived from molecular-dynamics simulations, which enable us to isolate the most relevant features driving the variation with temperature of both structure factors. The relevance of the present results regarding some recent phenomenological approaches developed towards the understanding of the dynamics of glasses at intermediate temperatures is finally discussed. ͓S0163-1829͑96͒00325-6͔

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“…11 In particular, a comparison between simulation results and experimental data regarding the elastic S(Q,Eϭ0) and static S(Q) quantities was provided for temperatures 5 K р T р 300 K. 11 The relevant point to make here regards the somewhat different shape of the first diffraction peak resulting from such an experiment ͑i.e., employing rather low incident energies͒ from that observed using total scattering techniques. 10 Notice that the shape of the peak in the calculated S͑Q͒ becomes closer to that measured using an incident energy of 5 meV ͑Ref. 11͒ than to that of Ref.…”

mentioning

confidence: 88%

“…2 shows a comparison of the static structure factors as measured by neutron diffraction, 10 that calculated using the previous potential 6 and the present one. As can easily be gauged from the referred graph the calculated S(Q) with either three-or four-body terms reproduce the oscillations above some 4 Å Ϫ1 in the experimental pattern rather satisfactorily.…”

mentioning

confidence: 99%

Importance of rings on the microscopic properties of a strong glass

1996

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An optimized interparticle potential has been developed for its use in computer molecular dynamics simulations of vitreous boron trioxide ͑v-B 2 O 3 ) which includes four-particle interactions. This is required to force the formation of planar six-membered ͑boroxol͒ rings in such simulations. As a result, a better agreement with the static structure factor is achieved, even though the percentage of atoms taking part in such structures is relatively small. ͓S0163-1829͑96͒02934-7͔The presence of a substantial amount of regular structures in strong glasses such as vitreous silica or boron trioxide has been a matter of heated debate for a number of years.1 The presence of such structures was postulated as a means to explain the origin of sharp peaks in the Raman spectra on the basis of calculations involving a few particles, 2 or more refined approaches which still involved idealized models of the amorphous solid such as the Bethe lattice.3 However, attempts to relate the presence of such structures with discernible features in the diffraction patterns lead to some recent controversies. In fact, results from calculations involving short-range structures only which portray most atoms as being involved in boroxol rings ͑about eighty percent͒ are confronted with attempts to reconstruct the structure of the glassy solid by means of Reverse Monte Carlo approaches, 4 where the best results are obtained if the percentage of boroxol rings is bounded below thirty percent ͑i.e., even the absence of any of those structures gives a better fit to experiment than those assuming a fraction of fifty percent or above͒. In fact, attempts to calculate the structure of vitreous B 2 O 3 using relatively small three-dimensional clusters of atoms forming boroxol rings have often encountered considerable difficulties when trying to reproduce the correct macroscopic density. This contrasts with results from molecular dynamics ͑MD͒ simulations 5,6 which, while satisfactorily accounting for the macroscopic density, have evidenced difficulties in reproducing the presence of a large number of atoms involved in planar, regular rings. On the contrary, such simulation results have shown the presence of cyclic structures albeit severely deformed ͑i.e., nonplanar͒ and of varied ring sizes.A recurrent critique against MD results on the structure and dynamics of v-B 2 O 3 has always been the lack of such structures in the computed equilibrium structure 2 of the glass. Such a shortcoming was rationalized in terms of ͑a͒ the huge cooling rates employed in the computer quench from the equilibrium liquid structure or ͑b͒ the lack of a more realistic potential function which including four-body interactions stabilizes such planar structures.Although little can be done to overcome the first of the difficulties referred above since quench rates comparable with experiment would imply vast resources of computer time, we set our endeavors to explore the feasibility of supplementing the potential function described in Refs. 6 and 7 with a four-body term to provi...

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A neutron diffraction investigation of the structure of vitreous boron trioxide

Cited by 179 publications

References 65 publications

Hyper-Raman scattering analysis of the vibrations in vitreous boron oxide

Hyper-Raman scattering analysis of the vibrations in vitreous boron oxide

Anomalous temperature dependence of the first diffraction peak in vitreous boron trioxide

Importance of rings on the microscopic properties of a strong glass

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