Mössbauer studies of materials used to immobilise industrial wastes

Forder, Susan D.; Bingham, Paul A.; McGann, Owen J.; Stennett, Martin C.; Hyatt, Neil C.

doi:10.1007/s10751-012-0700-x

Cited by 6 publications

(13 citation statements)

References 18 publications

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“…Two doublets were fitted to the spectra acquired from the CUP sample, Fig. (a); IS and QS of the doublets were consistent with the presence of sixfold and fivefold coordinated Fe 3+ as previously observed . The spectra acquired from the HIP sample, Fig.…”

Section: Resultssupporting

confidence: 72%

“…The Mössbauer data acquired from the HIP sample (prepared by milling at 4.32 m/s for 30 min with zinc stearate) are representative of data obtained from the entire suite of samples prepared using different lubricants and milling conditions. Previous 57 Fe Mössbauer analysis of Fe doped zirconolites showed that spectra could be fitted using two doublets indicating two distinct Fe coordination environments. This was consistent with substitution of Fe across the distinct Ti cations site in monoclinic zirconolite, which adopt sixfold and fivefold symmetry in a 2:1 ratio.…”

Section: Resultsmentioning

confidence: 92%

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Influence of Lubricants and Attrition Milling Parameters on the Quality of Zirconolite Ceramics, Consolidated by Hot Isostatic Pressing, for Immobilization of Plutonium

Squire

Maddrell

Hyatt

et al. 2014

Int J Applied Ceramic Tech

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The effect of attrition milling on the processing of precursor oxides was investigated, with reference to the fabrication of titanate ceramics for the immobilization of plutonium and actinides, consolidated by hot isostatic pressing. Difficulties encountered during the lubricant removal step masked any correlation between the milling conditions and the final product. Four lubricants were investigated zinc stearate, Ceridust TM , polyethylene glycol and oleic acid. The precursor blends were added to these lubricants to ensure the powders remained free flowing while dry milling in an attrition mill. All except Ceridust TM allowed the milled powders to be freely discharged. Examination of the products showed that each sample was highly porous and all were below the target minimum of 92 % of theoretical density. XRD and SEM analysis showed the production of a multiphase ceramic (zirconolite, perovskite, ilmenite) rather than the single target phase zirconolite. The impact of incomplete lubricant burn out on the oxidation states of Ce and Fe was investigated by XANES and M€ ossbauer spectroscopy, respectively. Suggested modifications to the HIP processing line, including the addition of an in situ sintered metal filter, the use of fumed metal oxides and the introduction of electrical conductivity in the precursors, are presented.

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Section: Resultssupporting

confidence: 72%

Section: Resultsmentioning

confidence: 92%

Influence of Lubricants and Attrition Milling Parameters on the Quality of Zirconolite Ceramics, Consolidated by Hot Isostatic Pressing, for Immobilization of Plutonium

Squire

Maddrell

Hyatt

et al. 2014

Int J Applied Ceramic Tech

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“…Aegirine and Fe-albite 185 glasses and crystallized aegirine were fitted by two overlapping doublets, whereas the as-186 quenched Fe-nepheline was fitted by one doublet plus two sextets characteristic of magnetite 187 (Fe 3 O 4 ) (Oh et al, 1998). As-quenched aegirine and Fe-albite samples (Figure 2b and c) were 188 fitted by xVBF functions, because at least three doublets were required in order to obtain robust 189 fits using Lorentzian lines, and xVBF has also been successfully used to fit Mössbauer spectra 190 for similar materials (Forder et al, 2013). This method provided robust fits with acceptable χ 2 191 using only two doublets to fit the glass spectrum, one each representing Fe 2+ (lower intensity) 192 This is a preprint, the final version is subject to change, of the American Mineralogist (MSA) Cite as Authors (Year) Title.…”

Section: Magnetic Measurements 177mentioning

confidence: 99%

Structure of NaFeSiO4, NaFeSi2O6, and NaFeSi3O8 glasses and glass-ceramics

Ahmadzadeh

Scrimshire

Mottram

et al. 2020

American Mineralogist

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15The crystallization of iron-containing sodium silicate phases holds particular importance, 16 both in the management high-level nuclear wastes and in geosciences. Here, we study three as-17 quenched glasses and their heat-treated chemical analogues, NaFeSiO 4 , NaFeSi 2 O 6 , and 18 NaFeSi 3 O 8 (with nominal stoichiometries from feldspathoid, pyroxene, and feldspar mineral 19 groups -i.e., Si/Fe = 1, 2, and 3 respectively) -using a variety of techniques. Phase analyses 20 revealed that as-quenched NaFeSiO 4 cannot accommodate all Fe in the glass phase (some Fe 21 crystallizes as Fe 3 O 4 ), whereas as-quenched NaFeSi 2 O 6 and NaFeSi 3 O 8 form amorphous glasses 22 upon quenching. NaFeSi 2 O 6 glass is the only composition that crystallizes into its respective 23 isochemical crystalline polymorph, i.e. aegirine, upon isothermal heat-treatment. As revealed by 24Mössbauer spectroscopy, iron is predominantly present as 4-coordinated Fe 3+ in all glasses, 25 though it is present as 6-coordinated Fe 3+ in the aegirine crystals (NaFeSi 2 O 6 ), as expected from 26 crystallography. Thus, Fe can form the crystalline phases in which it is octahedrally coordinated, 27 even though it is mostly tetrahedrally coordinated in the parent glasses. Thermal behavior, 28 magnetic properties, iron redox state (including Fe K-edge X-ray absorption), and vibrational 29 properties (Raman spectra) of the above compositions are discussed. 30 31

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“…Fe 2+ and Fe 3+ were assigned by considering the work of Darby-Dyar et al [26]. Mössbauer parameters from the literature for iron phosphate glasses [27], FeP 2 O 6 [28], Fe(PO 3 ) 3 [29] and Fe 2 (P 2 O 6 ) [28,30] were used as references in the fitting. The magnetite used in this work matched with pdf card 19-629, and contained 69% Fe 3+ and 31% Fe 2+ .…”

Section: Iron Phosphate Glass Compositesmentioning

confidence: 99%

“…It is accepted that higher Fe 3+ content will increase the connectivity of the glass network and its chemical durability [27,33]. In this work, it is shown that the sample processed by microwave melting for 20 min has an increased amount of Fe 3+ namely 77% compared to 50% in the level in the glass melted conventionally at 1150°C for 3 h. Thus it is shown that the use of microwave glass melting (at least in the laboratory) can reduce the processing time from hours to minutes, hence if it can be successfully scaled up and used in waste vitrification, use of a microwave furnace will both potentially save energy and be cost effective.…”

Section: Tablementioning

confidence: 99%