Monazite as a suitable actinide waste form

Schlenz, Hartmut; Heuser, J.; Neumann, Andreas; Schmitz, Stephan; Bosbach, Dirk

doi:10.1524/zkri.2013.1597

Cited by 82 publications

(55 citation statements)

References 111 publications

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“…This locally leads to "hot" 17) and (18). Note that not all data points are plotted for the sake of clarity.…”

Section: Discussionmentioning

confidence: 99%

“…An optimal waste form must be able to withstand the cumulative radiation damage produced by the decay of the radioactive nuclei and the environmental conditions in the repository without mechanical disintegration. Natural samples of monazite often contain uranium and thorium (up to 27 wt.% of UO 2 + ThO 2 ), but are not found in the metamict state and posses low dissolution rates [18]. Studies of irradiation effects with ions in the elastic collision regime show a transition into an amorphous state [19].…”

Section: Introductionmentioning

confidence: 99%

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In situ Resonant Ultrasound Spectroscopy during irradiation of solids with relativistic heavy ions

et al. 2015

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“…This locally leads to "hot" 17) and (18). Note that not all data points are plotted for the sake of clarity.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

In situ Resonant Ultrasound Spectroscopy during irradiation of solids with relativistic heavy ions

et al. 2015

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“…They also find applications in the nuclear cycle, either as host matrices for actinide radwastes or, more recently, as products of the reaction of the spent nuclear fuel with tributyl phosphate during the reprocessing [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

Section: M'mentioning

confidence: 99%

Structural study of polymorphism and thermal behavior of CaZr(PO4)2

Brégiroux

Wallez

Popa

2015

Solid State Sciences

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The crystal structure of CaZr(PO 4 ) 2 has been revised by ab initio Rietveld analysis of X-ray powder diffraction data. At room temperature, CaZr(PO 4 ) 2 crystallizes in the orthorhombic space group Pna2 1 (Z = 4). Differential thermal analysis suggests a reversible second order transition at 1000°C confirmed by high temperature XRD analysis that brings out the existence of a high temperature form, very similar to the room temperature one, but more symmetrical (Pnma, Z = 4). Analysis of the crystal parameters evolution during heating reveals that CaZr(PO 4 ) 2 exhibits a quite low thermal expansion coefficient of 6.11 10 -6 K -1 .This value stems from a combination of several mechanisms, including Coulombic repulsion and bridging oxygen rocking motion.Keywords: Crystal structure; thermal expansion; calcium zirconium phosphate Highlights:Room temperature structure CaZr(PO 4 ) 2 was revised A high temperature form of CaZr(PO 4 ) 2 was described for the first time Thermal expansion of CaZr(PO 4 ) 2 was studied on the basis of the evolution of the crystal parameters evolution during heating M

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“…In many previous works, the monazite-type lanthanum orthophosphate (LaPO 4 ), and xenotime one (YPO 4 ) has been suggested as matrices for radioactive waste immobilization (radioactive rare earth elements or trivalent actinides) and sensors [1][2][3][4][5][6][7][8]. Nanopowder-based ceramics designed for immobilizing purpose should possess high chemical resistance and isomorphic capacity, high durability and thermal stability.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Thermal Behavior of Nanopowders in LaPO4-YPO4(-H2O), LaPO4-LuPO4(-H2O) and YPO4-ScPO4(-H2O) Systems for Ceramic Matrices

Mezentseva

Àlex

Osipov

et al. 2017

JNMR

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Nanosized powders in the LaPO 4 -YPO 4 (-H 2 O), LaPO 4 -LuPO 4 (-H 2 O) and YPO 4 -ScPO 4 (-H 2 O) systems have been synthesized to increase the mutual solubility of initial components and to prepare effective ceramic matrices by sintering them. Ceramic matrices were characterized by high isomorphic capacity, thermal and chemical resistance. Ln" x PO 4 ·nH 2 O nanopowders; Ceramic matrices; Thermal; Keywords:Chemical stability technique with inverse precipitation and further dehydrated upon high heating rate to retain nanoscale. From this point of view the aim of this study was to investigate peculiarities of formation of nanopowders in the systems where components belong to the same or different structural groups, to determine their isomorphic capacity, to study thermal behavior, and thereby to develop physical and chemical approaches to prepare ceramic samples (as matrices) based on them. In this case the second component plays a role of immobilized ion (isotope).The hydrated La orthophosphate crystallizes in hexagonal rhabdophane-type system upon precipitation and contain 0.5-3 moles of H 2 O per formula unit. At temperature higher than 600 °C nanosized crystals loose water molecules and transform into monoclinic monazite-type form [9]. Yttrium, lutetium and scandium orthophosphates, hydrated and dehydrated, crystallizes in tetragonal xenotime-type form [9,10]. In this instance it was expected formation of limited solid solutions in the LaPO 4 -YPO 4 (- Hydrated rare earth orthophosphate nanopowders were synthesized using sol-gel method at stoichiometric ratio of interacting components Ln(NO 3 ) 3 and NH 4 H 2 PO 4 in an aqueous solution in the form of stable colloids that coagulate at pH ≈ 7 [9-11]. The use of reverse precipitation as it was shown allows improving further physico-mechanical properties of ceramic samples (matrices) obtained by sintering of nanopowders preliminary calcined to remove water from crystalline lattice [10,11]. ExperimentalThe initial reagents for rare earth orthophosphate systems were REE 2 O 3 (special-purity grade, 99.999%), mono substituted ammonium phosphate (special-purity grade, 99.5%), nitric acid (special-purity grade, 70%), aqua ammonia (special-purity grade, 25%), and distilled water. Synthesis of Ln' 1-x Ln" x PO 4 nH 2 O nanopowders was performed by sol-gel technique according the reactions described [11].The proper pH ≈ 7 for complete precipitation was reached by NH 4 OH addition. The precipitates were kept in the mother liquor for 24 h, washed after that by decantation, filtered off, and air-dried at 110 °C for 24 h [9,11]. For X-ray powder diffraction analysis DRON-3 diffractometer (Russia) was used. Recording parameters were as follows: Ni-filtered CuK α radiation, 38 kV, time constant 1, scanning speed 1 degree per minute. The thermal behavior of the samples was studied by means of stepwise heating of powders compacted into tablets under a pressure of 8-10 MPa within the temperature range of 850-1700 °C with further analysis by XRD or differential scannin...

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Monazite as a suitable actinide waste form

Cited by 82 publications

References 111 publications

In situ Resonant Ultrasound Spectroscopy during irradiation of solids with relativistic heavy ions

In situ Resonant Ultrasound Spectroscopy during irradiation of solids with relativistic heavy ions

Structural study of polymorphism and thermal behavior of CaZr(PO4)2

Synthesis and Thermal Behavior of Nanopowders in LaPO4-YPO4(-H2O), LaPO4-LuPO4(-H2O) and YPO4-ScPO4(-H2O) Systems for Ceramic Matrices

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