The infrared and Raman spectra of Na substituted β-TCP are presented for various levels of substi... more The infrared and Raman spectra of Na substituted β-TCP are presented for various levels of substitution. The influence of Na content on main vibrational modes appears significant and among them the ν1 symmetric stretching band is very sensitive to PO4 3- tetrahedrons environment. Thus, this mode was particularly investigated and has been decomposed using Lorentzian shapes components. We assigned the calculated components to the different types of PO4 3- tetrahedrons present in the crystalline structure.
ABSTRACT Several substituted â-tricalcium phosphates have been prepared with different cations (m... more ABSTRACT Several substituted â-tricalcium phosphates have been prepared with different cations (monovalent, divalent and trivalent) and at various levels of substitution. Structural investigations have proved that fewer than ~10% wt substitution, the substituted compounds are isostructural to â- TCP, leading to solid solutions. These samples have been characterized by infrared and Raman spectroscopies. The vibrational spectra show mainly the bands related to the vibrations of PO43- tetrahedrons present in the structure. As Raman scattering and infrared absorption are local probes, the bands are sensitive to the local environment of the distinct tetrahedrons, related to the site of substitution and to the nature of the cations.
Polycrystalline samples of Mn1-xCuxWO4 (x ≤ 0.5) have been prepared by a solid-state synthesis as... more Polycrystalline samples of Mn1-xCuxWO4 (x ≤ 0.5) have been prepared by a solid-state synthesis as well as from a citrate synthesis at moderate temperature (850 °C). The goal is to study changes in the structural, magnetic, and dielectric properties of magnetoelectric type-II multiferroic MnWO4 caused by replacing Jahn-Teller-inactive Mn(2+) (d(5), S = 5/2) ions with Jahn-Teller-active Cu(2+) (d(9), S = 1/2) ions. Combination of techniques including scanning electron microscopy, powder X-ray and neutron diffraction, and Raman spectroscopy demonstrates that the polycrystalline samples with low copper content 0 ≤ x ≤ 0.25 are solid solution that forms in the monoclinic P2/c space group. Rietveld analyses indicate that Cu atoms substitutes for Mn atoms at the Mn crystallographic site of the MnWO4 structure and suggest random distributions of Jahn-Teller-distorted CuO6 octahedra in the solid solution. Magnetic susceptibility reveals that only 5% of Cu substitution suppresses the nonpolar...
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
New supramolecular spirooxazine and spiropyran/polyoxotungstate materials have been designed. The... more New supramolecular spirooxazine and spiropyran/polyoxotungstate materials have been designed. Their solid-state photochromic performances are strongly exalted compared to their isostructural Mo counterparts due to a more favorable electronic effect.
Comptes Rendus de l'Académie des Sciences - Series IIC - Chemistry, 1998
ABSTRACT Synthesis and structure of a new variety of indium phosphate β-InPO4. A new high tempera... more ABSTRACT Synthesis and structure of a new variety of indium phosphate β-InPO4. A new high temperature allotropie form of indium phosphate, β-InPO4, has been obtained through quenching of an amorphous InPO4 phase heated for one hour at 1 300 °C. The two precursor amorphous phases, prepared according to two different soft chemistry procedures, lead to the same β derivative. The β-InPO4 structure is the same as the high-temperature varieties presented by MgSO4 and CoSO4, with an orthorhombic cell and the parameters a = 8.8800(1) Å, b = 6.8989(1) Å, c = 4.8082(1) Å, V= 294.56(1) Å3 and Z = 4. The space group is Pnma. The structure was refined using the Rietveld method (Rp = 0,04l, Rwp = 0,056 et χ2 = 2,63). It is built from [InO6] octahedra sharing edges to constitute [InO4] chains running in one direction and linked by [PO4] tetrahedra. The α and β structures are compared and discussed.
Acta crystallographica. Section C, Crystal structure communications, Jan 15, 2000
A new triclinic polymorphic form of N,N'-diphenyl-1,4-phenylenediamine (C(6)H(5)NHC(6)H(4)NHC... more A new triclinic polymorphic form of N,N'-diphenyl-1,4-phenylenediamine (C(6)H(5)NHC(6)H(4)NHC(6)H(5)) has been obtained through appropriate recrystallization of the orthorhombic form. It crystallized in the centrosymmetric space group P$\overline 1$, with two half molecules as the asymmetric unit.
Technetium is a long-lived product of nuclear fission which commonly exhibits two oxidation state... more Technetium is a long-lived product of nuclear fission which commonly exhibits two oxidation states (IV and VII). Siderite (FeCO3), suspected to be formed as a container corrosion product in geological radioactive waste repositories, may concentrate by coprecipitation more than 90% of technetium-99, present as Tc(IV) in surrounding aqueous fluids. X-ray diffraction and transmission electron microscopy measurements indicate that technetium can be incorporated within the siderite structure, even if we note that technetium-bearing green rust phase may also be observed. These results suggest that siderite might play a beneficial role in limiting Tc diffusion to the next environment of nuclear waste repositories.
Journal de Chimie Physique et de Physico-Chimie Biologique, 1998
In this work, photoconverted PPV film is characterized by means of optical absorption, photolumin... more In this work, photoconverted PPV film is characterized by means of optical absorption, photoluminescence, infrared absorption (IR), X-ray diffraction and electrochemical doping. The photoconverted PPV has optical properties close to standard PPV, and electrochemical ones close to thermoconverted PPV at 180 circC. Dans ce travail, un film de PPV photoconverti est caractérisé au moyen de l'absorption optique, de la photoluminescence,
The infrared and Raman spectra of Na substituted β-TCP are presented for various levels of substi... more The infrared and Raman spectra of Na substituted β-TCP are presented for various levels of substitution. The influence of Na content on main vibrational modes appears significant and among them the ν1 symmetric stretching band is very sensitive to PO4 3- tetrahedrons environment. Thus, this mode was particularly investigated and has been decomposed using Lorentzian shapes components. We assigned the calculated components to the different types of PO4 3- tetrahedrons present in the crystalline structure.
ABSTRACT Several substituted â-tricalcium phosphates have been prepared with different cations (m... more ABSTRACT Several substituted â-tricalcium phosphates have been prepared with different cations (monovalent, divalent and trivalent) and at various levels of substitution. Structural investigations have proved that fewer than ~10% wt substitution, the substituted compounds are isostructural to â- TCP, leading to solid solutions. These samples have been characterized by infrared and Raman spectroscopies. The vibrational spectra show mainly the bands related to the vibrations of PO43- tetrahedrons present in the structure. As Raman scattering and infrared absorption are local probes, the bands are sensitive to the local environment of the distinct tetrahedrons, related to the site of substitution and to the nature of the cations.
Polycrystalline samples of Mn1-xCuxWO4 (x ≤ 0.5) have been prepared by a solid-state synthesis as... more Polycrystalline samples of Mn1-xCuxWO4 (x ≤ 0.5) have been prepared by a solid-state synthesis as well as from a citrate synthesis at moderate temperature (850 °C). The goal is to study changes in the structural, magnetic, and dielectric properties of magnetoelectric type-II multiferroic MnWO4 caused by replacing Jahn-Teller-inactive Mn(2+) (d(5), S = 5/2) ions with Jahn-Teller-active Cu(2+) (d(9), S = 1/2) ions. Combination of techniques including scanning electron microscopy, powder X-ray and neutron diffraction, and Raman spectroscopy demonstrates that the polycrystalline samples with low copper content 0 ≤ x ≤ 0.25 are solid solution that forms in the monoclinic P2/c space group. Rietveld analyses indicate that Cu atoms substitutes for Mn atoms at the Mn crystallographic site of the MnWO4 structure and suggest random distributions of Jahn-Teller-distorted CuO6 octahedra in the solid solution. Magnetic susceptibility reveals that only 5% of Cu substitution suppresses the nonpolar...
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
New supramolecular spirooxazine and spiropyran/polyoxotungstate materials have been designed. The... more New supramolecular spirooxazine and spiropyran/polyoxotungstate materials have been designed. Their solid-state photochromic performances are strongly exalted compared to their isostructural Mo counterparts due to a more favorable electronic effect.
Comptes Rendus de l'Académie des Sciences - Series IIC - Chemistry, 1998
ABSTRACT Synthesis and structure of a new variety of indium phosphate β-InPO4. A new high tempera... more ABSTRACT Synthesis and structure of a new variety of indium phosphate β-InPO4. A new high temperature allotropie form of indium phosphate, β-InPO4, has been obtained through quenching of an amorphous InPO4 phase heated for one hour at 1 300 °C. The two precursor amorphous phases, prepared according to two different soft chemistry procedures, lead to the same β derivative. The β-InPO4 structure is the same as the high-temperature varieties presented by MgSO4 and CoSO4, with an orthorhombic cell and the parameters a = 8.8800(1) Å, b = 6.8989(1) Å, c = 4.8082(1) Å, V= 294.56(1) Å3 and Z = 4. The space group is Pnma. The structure was refined using the Rietveld method (Rp = 0,04l, Rwp = 0,056 et χ2 = 2,63). It is built from [InO6] octahedra sharing edges to constitute [InO4] chains running in one direction and linked by [PO4] tetrahedra. The α and β structures are compared and discussed.
Acta crystallographica. Section C, Crystal structure communications, Jan 15, 2000
A new triclinic polymorphic form of N,N'-diphenyl-1,4-phenylenediamine (C(6)H(5)NHC(6)H(4)NHC... more A new triclinic polymorphic form of N,N'-diphenyl-1,4-phenylenediamine (C(6)H(5)NHC(6)H(4)NHC(6)H(5)) has been obtained through appropriate recrystallization of the orthorhombic form. It crystallized in the centrosymmetric space group P$\overline 1$, with two half molecules as the asymmetric unit.
Technetium is a long-lived product of nuclear fission which commonly exhibits two oxidation state... more Technetium is a long-lived product of nuclear fission which commonly exhibits two oxidation states (IV and VII). Siderite (FeCO3), suspected to be formed as a container corrosion product in geological radioactive waste repositories, may concentrate by coprecipitation more than 90% of technetium-99, present as Tc(IV) in surrounding aqueous fluids. X-ray diffraction and transmission electron microscopy measurements indicate that technetium can be incorporated within the siderite structure, even if we note that technetium-bearing green rust phase may also be observed. These results suggest that siderite might play a beneficial role in limiting Tc diffusion to the next environment of nuclear waste repositories.
Journal de Chimie Physique et de Physico-Chimie Biologique, 1998
In this work, photoconverted PPV film is characterized by means of optical absorption, photolumin... more In this work, photoconverted PPV film is characterized by means of optical absorption, photoluminescence, infrared absorption (IR), X-ray diffraction and electrochemical doping. The photoconverted PPV has optical properties close to standard PPV, and electrochemical ones close to thermoconverted PPV at 180 circC. Dans ce travail, un film de PPV photoconverti est caractérisé au moyen de l'absorption optique, de la photoluminescence,
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