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V Brandel - One of the best experts on this subject based on the ideXlab platform.
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synthesis and characterization of uranium iv phosphate Hydrogenphosphate hydrate and cerium iv phosphate Hydrogenphosphate hydrate
Journal of Solid State Chemistry, 2005Co-Authors: V Brandel, Nicolas Clavier, Nicolas DacheuxAbstract:Abstract A new uranium (IV) phosphate of proposed formula U2(PO4)2HPO4·H2O, i.e. uranium phosphate-Hydrogenphosphate hydrate (UPHPH), was synthesized in autoclave and/or in polytetrafluoroethylene closed containers at 150 °C by three ways: from uranium (IV) hydrochloric solution and phosphoric acid, from uranium dioxide and phosphoric acid and by transformation of the uranium Hydrogenphosphate hydrate U(HPO4)2·nH2O. The new product appears similar to the previously published thorium phosphate-Hydrogenphosphate hydrate Th2(PO4)2HPO4·H2O (TPHPH). From preliminary studies, it was found that UPHPH crystallizes in monoclinic system ( a = 2.1148 ( 7 ) nm , b = 0.6611 ( 2 ) nm , c = 0.6990 ( 3 ) nm , β = 91.67 ( 3 ) ° and V = 0.9768 ( 10 ) nm 3 ). Heated under inert atmosphere, this compound is decomposed above 400 °C into uranium phosphate-triphosphate U2(PO4)P3O10, uranium diphosphate α -UP2O7 and diuranium oxide phosphate U2O(PO4)2. Crystallized cerium (IV) phosphate-Hydrogenphosphate hydrate Ce2(PO4)2HPO4·H2O (CePHPH) was also synthesized from (NH4)2Ce(NO3)6 and phosphoric acid solutions by the same method (monoclinic system: a = 2.1045 ( 5 ) nm , b = 0.6561 ( 2 ) nm , c = 0.6949 ( 2 ) nm , β = 91.98 ( 1 ) ° and V = 0.9588 ( 9 ) nm 3 ). When heating above 600 °C, cerium (IV) is reduced into Ce (III) and forms a mixture of CePO4 (monazite structure) and CeP3O9.
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Characterization of the thorium phosphate-Hydrogenphosphate hydrate (TPHPH) and study of its transformation into the thorium phosphate-diphosphate ($\beta$-TPD)
Materials Research Bulletin, 2005Co-Authors: N. Dacheux, V Brandel, Nicolas Clavier, G. Wallez, J. Emery, M. Quarton, M. GenetAbstract:The preparation of thorium phosphate-diphosphate (Th4(PO4)4P2O7, TPD) was developed through the precipitation of thorium phosphate-Hydrogenphosphate hydrate (Th2(PO4)2(HPO4)·H2O, TPHPH) at 150–160 °C in closed PTFE container or in autoclaves. From EPMA analyses and SEM observations, the initial precipitate was single phase and multilayered. The behaviour of TPHPH (orthorhombic system with a = 21.368(2) Å, b = 6.695(1) Å and c = 7.023(1) Å) was followed when heating up to 1250 °C. It was first dehydrated leading to the anhydrous thorium phosphate-Hydrogenphosphate (TPHP, orthorhombic system with a = 21.229(2) Å, b = 6.661(1) Å and c = 7.031(1) Å at 220 °C) after heating between 180 and 200 °C. This one turned progressively into the new low-temperature variety of TPD (called α-TPD, orthorhombic system with a = 21.206(2) Å, b = 6.657(1) Å and c = 7.057(1) Å at 300 °C) correlatively to the condensation of Hydrogenphosphate groups into diphosphate entities. These three phases (TPHPH, TPHP and α-TPD) exhibit closely related 2D layered structures, therefore different from the 3D structure of the thorium phosphate-diphosphate (high-temperature variety). This latter compound, now called β-TPD, was obtained by heating α-TPD above 950 °C. All the techniques involved in this study (XRD, Raman and IR spectroscopy, 1H and 31P NMR) confirmed the successive chemical reactions proposed.
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Hydrothermal Synthesis and Characterization of the Thorium Phosphate Hydrogenphosphate, Thorium Hydroxide Phosphate, and Dithorium Oxide Phosphate
IEEE Journal of Solid-state Circuits, 2001Co-Authors: V Brandel, Nicolas Dacheux, Michel Genet, Renaud PodorAbstract:Because of its low solubility in water and high thermal stability, thorium phosphate diphosphate (TPD), Th4(PO4)4P2O7, seems to be a very good matrix for radionuclide immobilization. During the leaching studies of this compound the formation of a new phase, different from the TPD was observed. In order to identify this phase, two other thorium phosphates: thorium phosphate–Hydrogenphosphate (TPHP), Th2(PO4)2HPO4·H2O, and thorium hydroxide phosphate (THOP), Th(OH)PO4, were synthesized in hydrothermal conditions then characterized. It appeared that the neoformed phase was identical to the TPHP.
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chemical conditions of synthesis of th4 po4 4p2o7 preparation of thorium phosphate Hydrogenphosphate as precursor
Chemistry of Materials, 1998Co-Authors: V Brandel, Nicolas Dacheux, M. Genet, And E Pichot, Emery J And, J Y Buzare, Renaud PodorAbstract:Thorium phosphate−diphosphate, Th4(PO4)4P2O7, is obtained, at high temperature (800−1250 °C), for a given ratio r = PO4/Th equal to 3/2 from a thorium compound and a phosphating reactant whatever the chemical conditions. This compound, whose solubility is very low, can be loaded in situ and used as a host matrix for radwaste storage. One of the methods for its synthesis involves the precipitation of a precursor, thorium phosphate−Hydrogenphosphate. This precursor is used as an adsorber for low concentrations of radionuclides and, after heating in air in the range 800−1200 °C, it is transformed into doped Th4(PO4)4P2O7. The optimum conditions for the precipitation process have been determined. Starting from 0.5−2 M solutions of thorium nitrate or chloride and (NH4)2HPO4 at pH = 9−9.5 at the ratio r = 3/2, a compound of general formula Th2(PO4)2HPO4·nH2O (n = 3−7) is synthesized. Its physicochemical properties have also been studied.
Nicolas Dacheux - One of the best experts on this subject based on the ideXlab platform.
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from thorium phosphate Hydrogenphosphate hydrate to β thorium phosphate diphosphate structural evolution to a radwaste storage ceramic
ChemInform, 2006Co-Authors: Gilles Wallez, Nicolas Clavier, Nicolas Dacheux, M. Quarton, Wouter Van BeekAbstract:β-Thorium phosphate diphosphate (β-TPD), considered as a very promising radwaste storage material, was obtained from thorium phosphate Hydrogenphosphate hydrate (TPHPH) precursor through dehydration and hydrogen phosphate condensation. The structures of TPHPH, intermediate α-thorium phosphate diphosphate (α-TPD) and its hydrate (α-TPDH) have been resolved ab initio by Rietveld analysis of their synchrotron diffraction patterns. All were found orthorhombic (space group Cmcm) and similarly composed of [ThPO4]44+ slabs alternating with disordered layers hosting either [HPO4·H2O]24− (TPHPH), [P2O7·2H2O]4− (α-TPDH), or [P2O7]4− (α-TPD), unlike the 3D structure of β-TPD. The diphosphate groups of α-TPD and α-TPDH are strongly bent. The irreversible transition to the final β-TPD consists in a shearing of the slabs and a reduction of the interslabs cavities that explains the stability of this high-temperature form.
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synthesis and characterization of uranium iv phosphate Hydrogenphosphate hydrate and cerium iv phosphate Hydrogenphosphate hydrate
Journal of Solid State Chemistry, 2005Co-Authors: V Brandel, Nicolas Clavier, Nicolas DacheuxAbstract:Abstract A new uranium (IV) phosphate of proposed formula U2(PO4)2HPO4·H2O, i.e. uranium phosphate-Hydrogenphosphate hydrate (UPHPH), was synthesized in autoclave and/or in polytetrafluoroethylene closed containers at 150 °C by three ways: from uranium (IV) hydrochloric solution and phosphoric acid, from uranium dioxide and phosphoric acid and by transformation of the uranium Hydrogenphosphate hydrate U(HPO4)2·nH2O. The new product appears similar to the previously published thorium phosphate-Hydrogenphosphate hydrate Th2(PO4)2HPO4·H2O (TPHPH). From preliminary studies, it was found that UPHPH crystallizes in monoclinic system ( a = 2.1148 ( 7 ) nm , b = 0.6611 ( 2 ) nm , c = 0.6990 ( 3 ) nm , β = 91.67 ( 3 ) ° and V = 0.9768 ( 10 ) nm 3 ). Heated under inert atmosphere, this compound is decomposed above 400 °C into uranium phosphate-triphosphate U2(PO4)P3O10, uranium diphosphate α -UP2O7 and diuranium oxide phosphate U2O(PO4)2. Crystallized cerium (IV) phosphate-Hydrogenphosphate hydrate Ce2(PO4)2HPO4·H2O (CePHPH) was also synthesized from (NH4)2Ce(NO3)6 and phosphoric acid solutions by the same method (monoclinic system: a = 2.1045 ( 5 ) nm , b = 0.6561 ( 2 ) nm , c = 0.6949 ( 2 ) nm , β = 91.98 ( 1 ) ° and V = 0.9588 ( 9 ) nm 3 ). When heating above 600 °C, cerium (IV) is reduced into Ce (III) and forms a mixture of CePO4 (monazite structure) and CeP3O9.
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Hydrothermal Synthesis and Characterization of the Thorium Phosphate Hydrogenphosphate, Thorium Hydroxide Phosphate, and Dithorium Oxide Phosphate
IEEE Journal of Solid-state Circuits, 2001Co-Authors: V Brandel, Nicolas Dacheux, Michel Genet, Renaud PodorAbstract:Because of its low solubility in water and high thermal stability, thorium phosphate diphosphate (TPD), Th4(PO4)4P2O7, seems to be a very good matrix for radionuclide immobilization. During the leaching studies of this compound the formation of a new phase, different from the TPD was observed. In order to identify this phase, two other thorium phosphates: thorium phosphate–Hydrogenphosphate (TPHP), Th2(PO4)2HPO4·H2O, and thorium hydroxide phosphate (THOP), Th(OH)PO4, were synthesized in hydrothermal conditions then characterized. It appeared that the neoformed phase was identical to the TPHP.
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chemical conditions of synthesis of th4 po4 4p2o7 preparation of thorium phosphate Hydrogenphosphate as precursor
Chemistry of Materials, 1998Co-Authors: V Brandel, Nicolas Dacheux, M. Genet, And E Pichot, Emery J And, J Y Buzare, Renaud PodorAbstract:Thorium phosphate−diphosphate, Th4(PO4)4P2O7, is obtained, at high temperature (800−1250 °C), for a given ratio r = PO4/Th equal to 3/2 from a thorium compound and a phosphating reactant whatever the chemical conditions. This compound, whose solubility is very low, can be loaded in situ and used as a host matrix for radwaste storage. One of the methods for its synthesis involves the precipitation of a precursor, thorium phosphate−Hydrogenphosphate. This precursor is used as an adsorber for low concentrations of radionuclides and, after heating in air in the range 800−1200 °C, it is transformed into doped Th4(PO4)4P2O7. The optimum conditions for the precipitation process have been determined. Starting from 0.5−2 M solutions of thorium nitrate or chloride and (NH4)2HPO4 at pH = 9−9.5 at the ratio r = 3/2, a compound of general formula Th2(PO4)2HPO4·nH2O (n = 3−7) is synthesized. Its physicochemical properties have also been studied.
Oswaldo Luiz Alves - One of the best experts on this subject based on the ideXlab platform.
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multiple step preparation and physicochemical characterization of crystalline α germanium Hydrogenphosphate
Journal of Solid State Chemistry, 2004Co-Authors: Ricardo Romano, Ana Isabel Ruiz, Oswaldo Luiz AlvesAbstract:The reaction between germanium oxide and phosphoric acid has previously been described and led to impure germanium Hydrogenphosphate samples with low crystallinity. A new multiple-step route involving the same reaction under refluxing and soft hydrothermal conditions is described for the preparation of pure and crystalline α-GeP. The physicochemical characterization of the samples allows accompaniment of the reaction evolution as well as determining short- and long-range structural organization. The phase purity of the α-GeP sample was confirmed by applying Rietveld's profile analysis, which also determined the cell parameters of its crystals.
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preparation of the conducting nanocomposites using molded inorganic matrix fibrous cerium iv Hydrogenphosphate as a self supported pyrrole polymerization agent
Journal of Materials Chemistry, 2003Co-Authors: Carla Verissimo, Oswaldo Luiz AlvesAbstract:New supported polypyrrole nanocomposites have been prepared and studied in this work. Self-supported sheets of fibrous cerium(IV) Hydrogenphosphate (CePf) were used as the inorganic matrix, since the fibrous morphology presented by this material makes molding possible, giving a desired shape to the final polypyrrole/CePf conducting nanocomposites. The influence of pyrrole concentration on the nanocomposite preparation was studied, as well as the influence of CePf on the polypyrrole characteristics. XRD, Raman, SEM and conductivity measurement data show the conducting polypyrrole coating CePf fibers, yielding self-supported sheets of organic–inorganic conducting nanocomposites.
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preparation of the conducting nanocomposites using molded inorganic matrix fibrous cerium iv Hydrogenphosphate as a self supported pyrrole polymerization agent
Journal of Materials Chemistry, 2003Co-Authors: Carla Verissimo, Oswaldo Luiz AlvesAbstract:New supported polypyrrole nanocomposites have been prepared and studied in this work. Self-supported sheets of fibrous cerium(IV) Hydrogenphosphate (CePf) were used as the inorganic matrix, since the fibrous morphology presented by this material makes molding possible, giving a desired shape to the final polypyrrole/CePf conducting nanocomposites. The influence of pyrrole concentration on the nanocomposite preparation was studied, as well as the influence of CePf on the polypyrrole characteristics. XRD, Raman, SEM and conductivity measurement data show the conducting polypyrrole coating CePf fibers, yielding self-supported sheets of organic–inorganic conducting nanocomposites.
Jose R Garcia - One of the best experts on this subject based on the ideXlab platform.
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hydrothermal synthesis crystal structure thermal behaviour and magnetic properties of a new ammonium chromium iron iii bis Hydrogenphosphate
Journal of Solid State Chemistry, 2019Co-Authors: Isabel Iglesias, Camino Trobajo, Belen F Alfonso, J A Blanco, Jose A Huidobro, Zakariae Amghouz, D Martinezblanco, Jose R GarciaAbstract:Abstract The hydrothermal synthesis and the chemical-physical characterization of an ammonium-chromium(III)-iron(III) bis(Hydrogenphosphate), Cr0.34Fe0.66NH4(HPO4)2 [CrFeNP] is reported. It was obtained in aqueous media by reaction between chromium(III) chloride, iron(III) chloride, urea, and orthophosphoric acid. The crystal structure of CrFeNP was determined from single-crystal X-ray diffraction data. It crystallizes in the triclinic system, space group P-1, and exhibits two types of different infinite tunnels along [0 1 0] and [1 0 0] directions, where the ammonium cations are located. Thermal analysis shows that the solid is stable up to ca. 600 K. The activation energy of the thermal decomposition up to 1273 K was computed by isoconversional methods. In addition, the magnetic behaviour of the material was investigated from magnetic susceptibility and magnetization measurements. CrFeNP undergoes two successive magnetic transitions at temperatures T C = 17.9 K and T t = 3.1 K, which could be related to a ferri- and an antiferromagnetic magnetic phase transitions, respectively.
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neutron powder diffraction investigation in ammonium iron iii bis Hydrogenphosphate
Journal of Physics: Conference Series, 2012Co-Authors: Belen F Alfonso, Camino Trobajo, Jose R Garcia, C Pique, Erik Kampert, I Mirebeau, N Rey, Rodriguez J Fernandez, M T Fernandezdiaz, J A BlancoAbstract:The deuterated form of ammonium iron(III) bis (Hydrogenphosphate), ND4Fe(DPO4)2, was investigated in detail from neutron powder diffraction data with a wavelength λ = 4.724 A. The material undergoes two successive magnetic phase transitions which are associated with the Fe3+ magnetic moments. One at TC = 17.82 ± 0.05 K is attributed to the ferrimagnetic order with the magnetic moments, μFI = 4.19 ± 0.02 μB at 4 K, lying on the crystallographic plane ac. The other transition is found to be at Tt = 3.52 ± 0.05 K due to an antiferromagnetic arrangement, with an equal moment antiphase structure that is characterized by a long-period propagation vector close to AF ≈ (1/16,0,1/16) and a magnetic moment for the Fe3+ ions of μAF = 4.41 ± 0.03 μB at 1.5 K. The low symmetry of its triclinic crystal structure and the complex pattern of competing superexchange pathways seem to be responsible for the existence of this double magnetic phase transition.
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synthesis and crystal structure of thorium bis Hydrogenphosphate monohydrate
Inorganic Chemistry, 2008Co-Authors: Miguel A Salvado, Pilar Pertierra, G R Castro, Camino Trobajo, Jose R GarciaAbstract:Microcrystals of Th(HPO 4) 2.H 2O were hydrothermally obtained from a Th(NO 3) 4-CO(NH 2) 2-H 3PO 3-H 2O system ( T = 180 masculineC). The structure [orthorhombic, Pbca, a = 9.1968(2) A, b = 18.6382(2) A, c = 8.7871(2) A], unlike alpha-Zr(HPO 4) 2.H 2O-type layered compounds, consists of a three-dimensional framework with PO 4 tetrahedra coordinated to Th atoms. The water molecule is also coordinated to the Th atom and projected toward small channels running along the directions of the a and c axes. The ThO 6O(w) environment could be described as a highly distorted pentagonal bipyramid.
Renaud Podor - One of the best experts on this subject based on the ideXlab platform.
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Hydrothermal Synthesis and Characterization of the Thorium Phosphate Hydrogenphosphate, Thorium Hydroxide Phosphate, and Dithorium Oxide Phosphate
IEEE Journal of Solid-state Circuits, 2001Co-Authors: V Brandel, Nicolas Dacheux, Michel Genet, Renaud PodorAbstract:Because of its low solubility in water and high thermal stability, thorium phosphate diphosphate (TPD), Th4(PO4)4P2O7, seems to be a very good matrix for radionuclide immobilization. During the leaching studies of this compound the formation of a new phase, different from the TPD was observed. In order to identify this phase, two other thorium phosphates: thorium phosphate–Hydrogenphosphate (TPHP), Th2(PO4)2HPO4·H2O, and thorium hydroxide phosphate (THOP), Th(OH)PO4, were synthesized in hydrothermal conditions then characterized. It appeared that the neoformed phase was identical to the TPHP.
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chemical conditions of synthesis of th4 po4 4p2o7 preparation of thorium phosphate Hydrogenphosphate as precursor
Chemistry of Materials, 1998Co-Authors: V Brandel, Nicolas Dacheux, M. Genet, And E Pichot, Emery J And, J Y Buzare, Renaud PodorAbstract:Thorium phosphate−diphosphate, Th4(PO4)4P2O7, is obtained, at high temperature (800−1250 °C), for a given ratio r = PO4/Th equal to 3/2 from a thorium compound and a phosphating reactant whatever the chemical conditions. This compound, whose solubility is very low, can be loaded in situ and used as a host matrix for radwaste storage. One of the methods for its synthesis involves the precipitation of a precursor, thorium phosphate−Hydrogenphosphate. This precursor is used as an adsorber for low concentrations of radionuclides and, after heating in air in the range 800−1200 °C, it is transformed into doped Th4(PO4)4P2O7. The optimum conditions for the precipitation process have been determined. Starting from 0.5−2 M solutions of thorium nitrate or chloride and (NH4)2HPO4 at pH = 9−9.5 at the ratio r = 3/2, a compound of general formula Th2(PO4)2HPO4·nH2O (n = 3−7) is synthesized. Its physicochemical properties have also been studied.
