Titanates, zirconates, aluminates and ferrites as waste forms for actinide immobilization

Stefanovsky, S. V.; Yudintsev, S. V.

doi:10.1070/rcr4606

Cited by 38 publications

(15 citation statements)

References 180 publications

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“…The presence of Ca and/or Zr in a keiviite‐type phase is supported by mineralogy, since similar structures are formed in CaZrSi 2 O 7 gittinsite, 63 CaZrTi 2 O 7 zirconolite‐2M, and K 2 ZrTi 2 O 7 khibinskite 64 . It is well‐known that Ca + Zr is a frequent substitution in crystals for 2 RE atoms 37,49 …”

Section: Discussionmentioning

confidence: 82%

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Partitioning of rare earths in multiphase nuclear waste glass‐ceramics

Chen

Marcial

Ahmadzadeh

et al. 2020

Int J of Appl Glass Sci

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Alumino‐borosilicate glass‐ceramics (GCs) containing alkali (Na), alkaline earth (Ca), rare earth (RE) (one of La … Lu, Y), and transition metals (Zr and Mo) were formulated to test the effects of composition and RE cation size on the crystallization of simulated nuclear waste GCs. Eight‐oxide glasses were formulated in the peraluminous ([Na2Oexcess]=[Na2O]‐[Al2O3]‐[ZrO2]<0) region with 10 mol.% RE2O3 and 15 mol.% B2O3. Glasses were melted and quenched, reheated, and slow‐cooled to promote crystallization, and then characterized using quantitative X‐ray diffraction and electron probe microanalysis. Transition metal phases [powellite (Ca,Na,RE)MoO4 and zirconia (Zr,RE)O2 or zircon (Zr,RE)SiO4] always formed, while borosilicate (RE3BSi2O10) or silicate [oxyapatite (RE,Ca,Na)10Si6O26 or keiviite (RE2Si2O7)] plus borate (REBO3) phases also formed, depending on the size of the RE cation and hence its preferred coordination number. All crystalline phases were found to contain RE elements, and often phases incorporated other cations (Zr, Ca, B) which were not nominally part of their pure stoichiometry. These results suggested that the glass formulation and RE size strongly influenced the RE environment in the glass and hence the crystal phases formed. The formation of RE borosilicate, versus separate RE borate and RE silicate phases, also suggested original differences in the glass structure.

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Section: Discussionmentioning

confidence: 82%

“…Because the Ca 2+ ion radius is very similar to La 3+ , Nd 3+ and Sm 3+ , 28 it substituted for the RE ion into the RE‐borosilicate phase. Zirconium is also frequently associated with Ca‐ and RE‐bearing silicate phases, such as pyrochlore (A 2 B 2 O 7 , eg, Nd 2 Zr 2 O 7 ) and zirconolite (CaZrTi 2 O 7 ) 37 …”

Section: Resultsmentioning

confidence: 99%

Partitioning of rare earths in multiphase nuclear waste glass‐ceramics

Chen

Marcial

Ahmadzadeh

et al. 2020

Int J of Appl Glass Sci

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“…Since Ringwood et al proposed the assemblages of mineral analog titanates, termed as Synthetic Rock (Synroc), as potential alternative host matrix of high level waste, and White et al detailed the crystal structure of the CaZrTi 2 O 7 zirconolite, it has been studied substantially as one of the key components for many Synroc formulations …”

Section: Introductionmentioning

confidence: 99%

CaZrTi₂O₇ zirconolite synthesis: From ceramic to glass‐ceramic

Kong

Karatchevtseva

Chironi

et al. 2019

Int J Applied Ceramic Tech

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The formation of CaZrTi 2 O 7 zirconolite and its crystallization in sodium aluminoborosilicate glass has been investigated via sintering in air. The ceramic precursor is prepared using a soft chemistry route to ensure ultimate mixing of the reactants at the molecular level. A nearly phase pure CaZrTi 2 O 7 zirconolite is formed after sintering the ceramic precursor at 1400°C for 12 hours. In order to form zirconolite glass-ceramics, various processing conditions are investigated including sintering temperatures, different glass composition precursors, and ceramic to glass weight ratios.Zirconolite crystallization on the surface and inside of glass-ceramic-pelletized samples is investigated. Higher ceramic to glass weight ratio leads to the formation of zirconolite as crystalline phase, which is quite dominant in glass.

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“…Onedimensional tunnel structures have been widely studied for their potential as fast-ionic conductors due to the high mobility of Asite cations in tunnels [10,50]. One class of these materials are termed Hollandites, which are in the priderite minerals group with a general formula of (K,Ba)(Ti,Fe) 8 O 16 , in which the majority of the M-site is replaced with Ti. Hollandite-type structures can exist in both tetragonal (I4/m) and monoclinic (I2/m) phases, exhibiting tunnels formed by linked oxygen octahedra.…”

Section: Model Single Phase Materials: Interfacial Characteristicsmentioning

confidence: 99%

“…In addition, CeO 2 is a well-known surrogate for UO 2 , and the principal actinide components of nuclear fuel UO 2 and PuO 2 also crystallize in fluorite structured oxides [7]. Garnet structures currently being evaluated for solid-state lithium battery electrolytes such as Li 7 La 3 Zr 2 O 12 (LLZO) are similar to based garnets being evaluated for nuclear waste immobilization of lanthanide fission products [8,9]. Finally, tunnel structured materials such as hollandites which incorporate mobile alkali ions such as Li, K, and Na in tunnels have been looked at as candidate battery electrode materials [10]; current work in solid state materials synthesis in the nuclear materials realm seeks to engineer the tunnels to block the motion of larger alkali ions such as Cs for immobilization applications [11].…”

Section: Introductionmentioning

confidence: 99%

An Interdisciplinary View of Interfaces: Perspectives Regarding Emergent Phase Formation

Brinkman

2017

Journal of Electrochemical Energy Conversion and Storage

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A perspective on emergent phase formation is presented using an interdisciplinary approach gained by working at the "interface" between diverse application areas, including solid oxide fuel cells (SOFCs) and ionic membrane systems, solid state lithium batteries, and ceramics for nuclear waste immobilization. The grain boundary interfacial characteristics of model single-phase materials in these application areas, including (i) CeO 2 , (ii) Li 7 La 3 Zr 2 O 12 (LLZO), and (iii) hollandite of the form Ba x Cs y Ga 2xþy Ti 8-2x-y O 16 , as well as the potential for emergent phase formation in composite systems, are discussed. The potential physical properties resulting from emergent phase structure and distribution are discussed, including an overview of existing three-dimensional (3D) imaging techniques recently used for characterization. Finally, an approach for thermodynamic characterization of emergent phases based on melt solution calorimetry is outlined, which may be used to predict the energy landscape including phase formation and stability of complex multiphase systems.

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Titanates, zirconates, aluminates and ferrites as waste forms for actinide immobilization

Cited by 38 publications

References 180 publications

Partitioning of rare earths in multiphase nuclear waste glass‐ceramics

Partitioning of rare earths in multiphase nuclear waste glass‐ceramics

CaZrTi₂O₇ zirconolite synthesis: From ceramic to glass‐ceramic

An Interdisciplinary View of Interfaces: Perspectives Regarding Emergent Phase Formation

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Titanates, zirconates, aluminates and ferrites as waste forms for actinide immobilization

Cited by 38 publications

References 180 publications

Partitioning of rare earths in multiphase nuclear waste glass‐ceramics

Partitioning of rare earths in multiphase nuclear waste glass‐ceramics

CaZrTi2O7 zirconolite synthesis: From ceramic to glass‐ceramic

An Interdisciplinary View of Interfaces: Perspectives Regarding Emergent Phase Formation

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Product

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About

CaZrTi₂O₇ zirconolite synthesis: From ceramic to glass‐ceramic