@prefix dcat: <http://www.w3.org/ns/dcat#> .
@prefix dct: <http://purl.org/dc/terms/> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
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              Isotopic substitution in neutron diffraction combined with structural simulations (Empirical Potential Structure Refinement, EPSR), has been employed to probe the sites occupied by Fe3+ and Fe2+ in an oxidized NaFeSi2O6 glass. This study reveals the presence of two populations of Fe3+ sites. 70% of Fe3+ is in tetrahedral sites (dFe3+-O=1.866±0.001 Å), as the remainder ferric iron and ferrous iron (~12% of total Fe) are 5-coordinated. 4-coordinated Fe3+ would act as a network former, while 5-coordinated Fe tends to segregate and would act as a modifier. The presence of this species, although minority, could explain the variations of some physical properties of Fe-bearing glasses. The substitution of Fe for Al was studied along the join NaFeSi2O6-NaAlSi2O6 using neutron diffraction combined with EPSR simulations. Whatever the Fe (and Al) content, the structural behaviour of Fe, Al3+ and Si4+ are unchanged. Al (4-coordinated) is randomly distributed in the silicate network, which is in agreement with a network former behaviour. As for Fe, the two populations observed in the NaFeSi2O6 end-member, and the structural behaviour we have assigned to them are preserved along the join. X-ray absorption spectroscopy near edge structure has been used for the first time at Al L2,3-edges to study the evolution of Al environment in those glasses. Finally, Mössbauer spectroscopy allowed the determination of redox ratio along the join.
            """ ;
    dct:identifier "NNT: 2007PA066385" ;
    dct:issued "2026-05-11T14:09:58.151082"^^xsd:dateTime ;
    dct:language "fr" ;
    dct:modified "2026-05-11T14:09:58.151087"^^xsd:dateTime ;
    dct:publisher <https://rec.harvest-normandie.data4citizen.com/organization/cce9db95-46d9-4dc2-84b6-764215d0a002> ;
    dct:title "Structure of glasses in the NaFeSi2O6 - NaA1Si2O6 system : structural behavior of iron" ;
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            vcard:fn "CCSD" ] ;
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    dcat:keyword "chimmatechemical-sciencesmaterial-chemistry",
        "data-unavailable",
        "diffraction-des-neutrons",
        "infoeu-reposemanticsdoctoralthesis",
        "simulations-numeriques",
        "spectroscopie-mossbauer",
        "structure-des-verres",
        "theses",
        "verres-silicates",
        "xanes-x-ray-absorption-near-edge-structure" ;
    dcat:landingPage <https://theses.hal.science/tel-00811196> .

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    dct:issued "2026-05-11T14:09:58.159642"^^xsd:dateTime ;
    dct:modified "2026-05-11T14:09:58.131288"^^xsd:dateTime ;
    dct:title "Structure of glasses in the NaFeSi2O6 - NaA1Si2O6 system : structural behavior of iron" ;
    dcat:accessURL <https://theses.hal.science/tel-00811196> .

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