Insertion du césium dans des britholites au strontium

Boughzala, Khaled; Hidouri, Mustapha; Salem, Ezzedine Ben; Chrifa, Ali Ben; Bouzouita, Khaled

doi:10.1016/j.crci.2007.06.010

Cited by 6 publications

(10 citation statements)

References 27 publications

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“…An earlier spectroscopic and structural study of Ca 10−x La x (PO 4 ) 6−x (SiO 4 ) x F 2 showed that the composition x = 2 is stable and the coupled substitutions of lanthanum by calcium and silicates by phosphates have occurred without structural modification [32]. The present work consists in studying the simultaneous substitution of lanthanum by neodymium in the designated composition x = 2.…”

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confidence: 89%

Lanthanum-Neodymium-Co-Substituted Calcium Fluorobritholites

Hidouri¹,

Albeladi²

2018

MSCE

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Britholites are considered as potential matrices for storage of nuclear wastes such as minor actinides and long-lived fission byproducts. This investigation is concerned with the study of simultaneous substitution in calcium fluor-britholite framework of two lanthanide ions assimilated to radionuclides. A series of calcium fluorbritholites doped with lanthanum and neodymium Ca 8 La 2−x Nd x (PO 4 ) 4 (SiO 4 ) 2 F 2 with 0 ≤ x ≤ 2 were prepared via a solid state reaction in the temperature range 1450˚C -1250˚C. The obtained products were characterized by several techniques such as Chemical analysis via Inductively coupled plasma Atomic emission spectrometry ICP-AES, X-ray diffraction (XRD), Fourier transformed infra-red spectroscopy FTIR and Nuclear magnetic resonance 31 P NMR (MAS). Obtained solid solutions containing lanthanum and neodymium in variable proportions were typically apatite of hexagonal structure P63/m spatial group. The stoichiometry of the powders was verified via the metal/(phosphate + silicate) molar ratios found at about 1.67. The lattice parameters a and c calculated by the Rietveld method decreased as neodymium level increased. Despite, the close respective sizes of lanthanum and neodymium ions ( VI r La3+ = 1.032Å, VI r Nd3+ = 0.983Å), their mutual substitutions led to solid solutions in whole range of composition with preferential occupation of Me (2) sites.

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Lanthanum-Neodymium-Co-Substituted Calcium Fluorobritholites

Hidouri¹,

Albeladi²

2018

MSCE

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“…L'analyse chimique de la composition e ´tudie ´e a e ´te ŕe ´alise ´e par spectroscopie a `fluorescence X. Les re ´sultats obtenus sont consigne ´s dans le Tableau 1 [21].…”

Section: Re ´Sultats Et Discussionunclassified

“…Les re ´sultats obtenus ont montre que ce sont les britholites monosilicate ´es qui sont les plus stables et par conse ´quent susceptibles de constituer une matrice pour le confinement des radionucle ´ides [15][16][17][18][19]. Par ailleurs, des e ´tudes qui se sont attache ´es a `l'incorporation du ce ´sium dans des britholites calciques ou strontiques ont montre ´qu'uniquement la composition monosilicate ´e (Me 7 La 2 Cs(PO 4 ) 5 (SiO 4 )F 2 , avec Me = Ca ou Sr) a e ´te ´obtenue a `l'e ´tat pur [20,21]. La connaissance de la re ´partition du ce ´sium entre les deux sites cationiques peut contribuer a `une meilleure compre ´hension de la fixation de cet e ´le ´ment par les britholites.…”

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“…Apre `s avoir subi un premier traitement a `800 8C pendant deux heures, l'e ´chantillon sous forme de pastille a e ´te ´de nouveau broye ´, homoge ´ne ´ise ´et mis en forme. Afin de limiter la volatilisation du ce ´sium [21], la pastille a e ´te ṕlace ´e dans une nacelle munie de couvercle, enrobe ´e par une poudre de me ˆme nature mais enrichie en carbonate de ce ´sium (20 % en masse), pour cre ´er une atmosphe `re autostabilisante, puis calcine ´e a `1100 8C pendant quatre heures. L'e ´quation de re ´action est la suivante :…”

Section: Incorporation Du Ce´siumunclassified

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Étude structurale de britholite au césium Sr7La2Cs(PO4)5(SiO4)F2

Boughzala

Gmati

Bouzouita

et al. 2010

Comptes Rendus. Chimie

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e ´tudes ont montre ´que les britholites sont capables de recevoir des radionucle ´ides comme le ce ´sium ou les actinides. Dans ce cadre, trois compositions de formules respectives Sr 8 LaCs(PO 4 ) 6 F 2 , Sr 7 La 2 Cs(PO 4 ) 5 (SiO 4 )F 2 et Sr 2 La 7 Cs(SiO 4 ) 6 F 2 ont e ´te ṕre ´pare ´es par re ´action a `l'e ´tat solide. Mais il semble qu'uniquement la composition monosilicate ´e a e ´te ´obtenue a `l'e ´tat pur. Dans ce pre ´sent travail, la diffraction des rayons X et la re ´sonance magne ´tique nucle ´aire ont e ´te ´utilise ´es pour analyser la structure de cette composition. Les re ´sultats obtenus ont montre ´que cette phase n'e ´tait pas re ´ellement pure, mais qu'elle e ´tait me ´lange ´e avec une phase secondaire SrLaCs(PO 4 ) 2 . L'affinement par la me ´thode de Rietveld a permis aussi de pre ´ciser la distribution des ions La 3+ et Cs + entre les deux sites cationiques de l'apatite.

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“…A solid state method was adopted to prepare strontium fluorobritholites compounds Sr 8 La 2Àx Nd x (PO 4 ) 4 (SiO 4 ) 2 F 2 with 0 ≤ x ≤ 2 [36]. The starting reagents: strontium fluoride SrF 2 (99.99%.…”

Section: Powder Synthesismentioning

confidence: 99%

Ionic Conductivity of Strontium Fluoroapatites Co-doped with Lanthanides

Kthiri¹,

Mehnaoui²,

Jebahi³

et al. 2022

Mineralogy

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Britholites derivatives of apatite’s that contain lanthanium and neodymium in the serial compounds Sr8La2−xNdx(PO4)4(SiO4)2F2 with 0 ≤ x ≤ 2 were subject of the present investigation. The solid state reaction was the route of preparing these materials. Several techniques were employed for the analysis and characterization of the synthesized powders. The chemical analysis results indicated that molar ratio Sr+La+NdP+Si was of about 1.67 value of a stoichiometric powder. The X-ray diffraction data showed single-phase apatites crystallizing in hexagonal structure with P63/m space group were successively obtained. Moreover, the substitution of lanthanium by neodymium in strontium phosphosilicated fluorapatite was total. This was confirmed by the a and c lattice parameters contraction when (x) varies coherently to the sizes of the two cations. The infrared spectroscopy and the 31P NMR (MAS) exhibited the characteristic bands of phosphosilicated fluorapatite. The pressureless sintering of the material achieved a maximum of 89% relative density. The sintered specimens indicated that the Nd content as well as the heating temperature affected the ionic conduction of the materials and the maximum was 1.73 × 10−6 S cm−1 obtained at 1052 K for x = 2.

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Insertion du césium dans des britholites au strontium

Cited by 6 publications

References 27 publications

Lanthanum-Neodymium-Co-Substituted Calcium Fluorobritholites

Lanthanum-Neodymium-Co-Substituted Calcium Fluorobritholites

Étude structurale de britholite au césium Sr7La2Cs(PO4)5(SiO4)F2

Ionic Conductivity of Strontium Fluoroapatites Co-doped with Lanthanides

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