LiDy(PO3)4

Single crystals of lithium dysprosium polyphosphate, LiDy(PO3)4, were prepared by the flux method. The atomic arrangement is built up by infinite (PO3)n chains extending along the b axis. Dy3+ and Li+ cations alternate in the middle of four such chains, with Dy⋯Li distances of 3.54 (1) and 3.48 (1) Å. The DyO8 dodeca­hedra and LiO4 tetra­hedra deviate significantly from the ideal geometry. Both Dy and Li occupy special positions (Wyckoff position 4e, site symmetry 2)

Terbium(III) hydrogendiphosphate(V) tetra­hydrate

The Tb atom of the title compound, TbHP2O7·4H2O, is coordinated by the O atoms of three symmetrically independent water mol­ecules and by five O atoms belonging to HP2O7 − groups. The TbO8 polyhedra are inter­connected by the diphospate anions, forming a three-dimensional network which is additionally stabilized by O—H⋯O hydrogen bonding between water mol­ecules and O atoms of the HP2O7 − anions. Uncoordinated water mol­ecules are situated in channels and are connected via hydrogen bonds with the framework

Étude qualitative de la croissance cristalline de HLnP₂O₇.3H₂O ; (Ln = La, Gd)

International audienceL'influence de la concentration des réactifs, du pH et de la température, ont été étudiées séparément pour déterminer les conditions d'obtention des cristaux HLnP2O7.3H2O (Ln=La, Gd). Les résultats ont montré que la cristallisation est favorisée, à température ambiante, pour des concentrations de réactifs relativement basses et dans un mélange dont le pH est optimum. Des monocristaux de HLaP2O7.3H2O et HGdP2O7.3H2O ont été obtenus de longueur respectives 150µm et 700µm. L'observation de l'évolution de la croissance de l'hydrate au gadolinium, par microscopie optique, a permis de conclure qu'elle se fait selon le mécanisme de nucléation bidimentionnelle. // The effect of reagents concentration, pH, and temperature on the crystallization of HLnP2O7.3H2O (Ln=La, Gd) has been determined separately. The results show that the crystallization is enhanced at ambient temperature, by reducing reagents concentrations and using an optimal value of pH. Monocrystals of HLaP2O7.3H2O and HGdP2O7.3H2O have been obtained respectively with a length of 150 µm and 700 µm. The observation of HGdP2O7.3H2O crystal state at different times of synthesis using optical microcopy indicates that the growth follows a bi-dimensional nucleation mechanism

Single crystal structure, vibrational study, and thermal behavior of a new rare earth diphosphate HYbP₂O₇·4H₂O

<p>A new ytterbium diphosphate: HYbP₂O₇·4H₂O was prepared via soft chemistry route from evaporation of aqueous solution. It was investigated by single crystal X-ray diffraction, vibrational spectroscopy, and thermal analysis.</p> <p>The framework of the title compound consists in an assemblage of HP₂O₇ groups and [YbO₅(H₂O)₂] polyhedra, giving rise to corrugated layers stacked along the <i>b</i> axis at <i>y</i> = 1/4 and <i>y</i> = 3/4. Between these layers are located two uncoordinated water molecules. The cohesion of this arrangement is well ensured by a three-dimensional network of water-layer and inter-layer hydrogen bonds of different strengths. Non-coincidences are observed between the majority of the IR and Raman bands and confirm a centrosymetric structure for this compound. Thermal analysis reveals the elimination of 4.5 water molecules per formula unit in three stages between 310 K and 1100 K, which correspond to the departure of the four crystallization water molecules and the OH group. A comparative study among hydrated lanthanide monohydrogendiphosphates known in the literature is presented.</p

Étude qualitative de la croissance cristalline de HLnP2_2O7_7·3H2_2O ; (Ln = La, Gd)

The effect of reagents concentration, pH, and temperature on the crystallization of HLnP$_2$O$_7$·3H$_2$O (Ln=La, Gd) has been determined separately. The results show that the crystallization is enhanced at ambient temperature, by reducing reagents concentrations and using an optimal value of pH. Monocrystals of HLaP$_2$O$_7$·3H$_2$O and HGdP$_2$O$_7$·3H$_2$O have been obtained respectively with a length of 150 µm and 700 µm. The observation of HGdP$_2$O$_7$·3H$_2$O crystal state at different times of synthesis using optical microcopy indicates that the growth follows a bi-dimensional nucleation mechanism.L’influence de la concentration des réactifs, du pH et de la température, ont été étudiées séparément pour déterminer les conditions d’obtention des cristaux HLnP$_2$O$_7$·3H$_2$O (Ln = La, Gd). Les résultats ont montré que la cristallisation est favorisée, à température ambiante, pour des concentrations de réactifs relativement basses et dans un mélange dont le pH est optimum. Des monocristaux de HLaP$_2$O$_7$·3H$_2$O et HGdP$_2$O$_7$·3H$_2$O ont été obtenus de longueur respectives 150 µm et 700 µm. L'observation de l’évolution de la croissance de l'hydrate au gadolinium, par microscopie optique, a permis de conclure qu’elle se fait selon le mécanisme de nucléation bidimensionnell