Study of lanthanum orthophosphates polymorphism, in view of actinide conditioning

Glorieux, Benoît; Matecki, M.; Fayon, Franck; Coutures, Jean-Pierre; Palau, S; Douy, André; Péraudeau, G.

doi:10.1016/j.jnucmat.2004.01.005

Cited by 52 publications

(46 citation statements)

References 20 publications

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“…Leaching experiments exhibit quite good resistance of Ln' 1-x Ln" x PO 4 matrices in a strongly acid HNO 3 solution (pH 1-2) at room temperature (Figure 8 & 9). The results of leaching experiments for Ln' 1-x Ln" x PO 4 are close to [20] for GdPO 4 in strongly HCl and HNO 3 solutions (pH 1-2) corresponding to value of ~10 -2 g L -1…”

Section: Synthesis and Thermal Behavior Of Nanopowders In Lapo 4 -Yposupporting

confidence: 66%

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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Section: Synthesis and Thermal Behavior Of Nanopowders In Lapo 4 -Yposupporting

confidence: 66%

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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“…It has been shown that dry milling a stoichiometric mixture of La(NO 3 ) 3 and NaH 2 PO 4 in a planetary ball mill allows obtaining needle-like nanometric rhabdophane-type LaPO 4 ·nH 2 O particles. The formation of the title phase takes place via a solid state reaction in a process which significantly reduces the time reportedly needed to obtain the same product by using different processing methods such as chemical reactions in an aqueous solution.…”

Section: Discussionmentioning

confidence: 99%

“…Amongst all rare-earth orthophosphates, lanthanum orthophosphate, LaPO 4 , is perhaps the one presenting a broader range of applications in different areas of technological interest. Thus, monoclinic monazite-type LaPO 4 presents very high melting point (>2000 • C), extremely low water solubility and chemical and thermal stability and, therefore, is currently under consideration as ceramic matrix for immobilizing high-level radioactive waste [2,3]. Doped with cerium and terbium, bulk LaPO 4 is a commercially applied lamp phosphor [4] while * Corresponding author.…”

Section: Introductionmentioning

confidence: 99%

“…Due to all these applications, finding new methods to prepare LaPO 4 is an area of interest in materials science. Lanthanum orthophosphates are normally prepared by chemical precipitation methods using La(NO 3 ) 3 , LaCl 3 , La(NO 3 ) 3 ·6H 2 O, La 2 O 3 or La(OH) 3 as lanthanum agents and H 3 PO 4 or (NH 4 ) 2 HPO 4 as phosphating agents. However, these methods are time-consuming and require multiple step reactions, precise pH control [7,8] or lead to harmful by-products such as hydrochloric acid [9].…”

Section: Introductionmentioning

confidence: 99%

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A rapid method to obtain nanometric particles of rhabdophane LaPO4·nH2O by mechanical milling

Díaz-Guillén

Fuentes

Gallini

et al. 2007

Journal of Alloys and Compounds

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“…Among the many REPO 4 phases, LaPO 4 stands out for its broader range of applications in different areas of technological interest [4][5][6][7][8][9]. In addition, monoclinic monazite-type LaPO 4 presents very high melting point (4 2000 1C), extremely low water solubility and chemical and thermal stability and, therefore, is currently under consideration as ceramic matrix for immobilizing high-level radioactive waste [4,7]. Doped with cerium and terbium, bulk LaPO 4 is a commercially applied lamp phosphor [10], while if doped with strontium, becomes a high-temperature proton conductor [11,12].…”

Section: Introductionmentioning

confidence: 99%

Thermal evolution, second phases, and sintering behavior of LaPO4·nH2O nanorods prepared by two different chemical synthesis routes

Colomer

Mosa

2015

Ceramics International

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Study of lanthanum orthophosphates polymorphism, in view of actinide conditioning

Cited by 52 publications

References 20 publications

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

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

A rapid method to obtain nanometric particles of rhabdophane LaPO4·nH2O by mechanical milling

Thermal evolution, second phases, and sintering behavior of LaPO4·nH2O nanorods prepared by two different chemical synthesis routes

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