Na7Mg13Nd(PO4)12

Investigations of the quasi-ternary system Na3PO4–Mg3(PO4)2–NdPO4 allowed us to obtain the new phosphate hepta­sodium trideca­magnesium neodymium dodeca­kis­phosphate, Na7Mg13Nd(PO4)12, by applying a flux method. The crystal structure is isotypic with that of the previously reported Na7Mg13 Ln(PO4)12 (Ln = Eu, La) compounds. It consists of a complex three-dimensional framework built up from an NdO8 polyhedron (m symmetry), an MO6 octa­hedron statistically occupied by M = Mg and Na, and eight MgOx (x = 5, 6) polyhedra (four with site symmetry m), linked either directely by sharing corners, edges and faces, or by one of the eight unique PO4 tetra­hedra through common corners. Two of the PO4 tetra­hedra are statisticaly disordered over a mirror plane. The whole structure can be described as resutling from an assembly of two types of structural units, viz [Mg4 MP4O22]∞ 2 layers extending parallel to (100) and stacked along [100], and [Mg4NdP4O36]∞ 1 undulating chains running along the [010] direction. The six different Na+ cations (five with site symmetry m and one with 0.5 occupancy) are situated in six distinct cavities delimited by the framework. The structure was refined from data of a racemic twin

The iron phosphate CaFe3(PO4)3O

A new iron phosphate, calcium triiron(III) tris­(phosphate) oxide, CaFe3(PO4)3O, has been isolated and shown to exhibit a three-dimensional structure built by FeO6 octa­hedra, FeO5 trigonal bipyramids and PO4 tetra­hedra. The FeOx (x = 5, 6) polyhedra are linked through common corners and edges, forming [Fe6O28]∞ chains with branches running along [010]. Adjacent chains are connected by the phosphate groups via common corners and edges, giving rise to a three-dimensional framework analogous to those of the previously reported SrFe3(PO4)3O and Bi0.4Fe3(PO4)3O structures, in which the Ca2+ cations occupy a single symmetry non-equivalent cavity

The iron phosphate NaBaFe2(PO4)3

A new iron phosphate, sodium barium diiron tris­(phosphate), NaBaFe2(PO4)3, has been synthesized by the flux method and shown to exhibit the well known langbeinite type structure. The Na, Ba and Fe atoms all lie on threefold axes, while the P and O atoms occupy general positions, one of the O atoms being disordered over two positions, with site occupancy factors of ca 0.7 and 0.3. The [Fe2(PO4)3]∞ framework consists of FeO6 octa­hedra sharing all their corners with the PO4 tetra­hedra. The Na+ and Ba2+ cations are almost equally distributed over two distinct cavities, in which they occupy slightly different positions

K0.53Mn2.37Fe1.24(PO4)3

During an attempt to crystallize potassium manganese diiron phosphate KMnFe2(PO4)3 by the flux method, a new phase, potassium dimanganese iron triphosphate, K0.53Mn2.37Fe1.24(PO4)3, was isolated. This phase, whose composition was confirmed by ICP analysis, is isotypic with the alluaudite-like phosphates, thus it exhibits the (A2)(A′2)(A1)(A′1)(A′′1)(M1)(M2)2(PO4)3 general formula. The site occupancies led to the following cation distribution: 0.53 K on A′2 (site symmetry 2), 0.31 Mn on A′′1, 1.0 Mn on M1 (site symmetry 2) and (0.62 Fe + 0.38 Mn) on M2. The structure is built up from infinite chains of edge-sharing M1O6 and M2O6 octa­hedra. These chains run along [10] and are connected by two different PO4 tetrahedra, one of which exhibits 2 symmetry. The resulting three-dimensional framework delimits large tunnels parallel to [001], which are partially occupied by the K+ and Mn2+ cations

Synthesis and crystal structure of a new alluaudite-like iron phosphate Na2CaMnFe(PO4)3

A new iron phosphate, disodium calcium manganese(II) iron(III) tris(phosphate), Na2CaMnFe(PO4)3, has been synthesized as single crystals by the flux technique. This compound crystallizes in the monoclinic space group C2/c. The structure belongs to the alluaudite structural type and thus, it obeys the X(2)X(1)M(1)M(2)2(PO4)3 general formula. Both the X(2) and X(1) sites are fully occupied by sodium, while M(1) is occupied by calcium and M(2) exhibits a statistical distribution of iron and manganese

X-ray diffraction, 31P NMR and europium photoluminescence properties of the Na2Ba1−xSrxMg(PO4)2 system related to the glaserite type structure

Different samples of a solid solution of glaserite-type structure with the general formula Na2Ba1−xSrxMg(PO4)2(0 ⩽ x ⩽ 1) were synthesized by the Pechini method and characterized by X-ray powder diffraction (XRD), 31P NMR spectroscopy and photoluminescence of europium doped compounds. The XRD patterns show that Na2Ba1−xSrxMg(PO4)2 system adopts the trigonal symmetry with the space group of PView the MathML source3¯m1 for 0 ⩽ x ⩽ 0.55 while from x = 0.6, it crystallizes in the monoclinic symmetry with the space group P21/a. The four resonances observed in the 31P NMR spectra for each composition of the system Na2Ba1−xSrxMg(PO4)2 (0 ⩽ x ⩽ 1) are interpreted on the basis of four configurations of statistical distribution (Ba2+/Sr2+) in the neighboring cationic sites of a PO4 tetrahedron. The photoluminescence of doped samples with divalent and trivalent europium was analyzed according to their compositions

RbCuFe(PO4)2

A new iron phosphate, rubidium copper(II) iron(III) bis(phosphate), RbCuFe(PO4)2, has been synthesized as single crystals by the flux method. This compound is isostructural with KCuFe(PO4)2 [Badri et al. (2011), J. Solid State Chem. 184, 937–944]. Its structure is built up from Cu2O8 units of edge-sharing CuO5 polyhedra, interconnected by FeO6 octahedra through common corners to form undulating chains that extend infinitely along the [011] and [01-1] directions. The linkage of such chains is ensured by the PO4 tetraedra and the resulting three-dimensional framework forms quasi-elliptic tunnels parallel to the [101] direction in which the Rb+ cations are located

Synthesis, crystal structure and spectroscopic characterization of a new cadmium phosphate, Na2Cd5(PO4)4

A novel cadmium phosphate compound Na2Cd5(PO4)4 was synthesized in single crystal and in powder forms using flux and Pechini methods, respectively. It was then characterized by single crystal X-ray diffraction, vibrational spectroscopy and photoluminescence measurements. This compound crystallizes in the monoclinic system with space group P21/a, lattice parameters a = 8.276(1) Å, b = 9.301(3) Å, c = 9.455(2) Å, β = 111.82 (1)° and Z = 2. The structure consists of (Na3/4,Cd1/4)O7, (Cd3/4,Na1/4)O6 and CdOx (x = 6, 7), polyhedra and PO4 tetrahedra linked through common corners or edges giving rise to a novel type of complex three-dimensional framework. This structure could be described in terms of [(Na3/4,Cd1/4)2(Cd3/4,Na1/4)2Cd3O16]∞ layers stacked parallel to the (2 0–3) plane and interconnected both directly and via PO4 tetrahedra by sharing common corners and edges. Vibrational spectroscopy and cadmium photoluminescence were analyzed according to the structural results

Synthesis and crystal structure of a new magnesium phosphate Na3RbMg7(PO4)6

A new magnesium phosphate, Na3RbMg7(PO4)6 [trisodium rubidium heptamagnesium hexakis(orthophosphate)], has been synthesized as single crystals by the flux method and exhibits a new structure type. Its original structure is built up from MgOx (x = 5 and 6) polyhedra linked directly to each other through common corners or edges and reinforced by corner-sharing with PO4 tetrahedra. The resulting anionic three-dimensional framework leads to the formation of channels along the [010] direction, in which the Na+ cations are located, while the Rb+ cations are located in large interstitial cavities

Etude de nouveaux matériaux phosphates de lithium et d'élément de transition comme électrode positive pour batteries LI-ION

Depuis la mise en évidence des potentialités du phosphate LiFePO4 comme électrode positive de batteries lithium-ion, un très fort regain d intérêt pour les phosphates de fer est actuellement observé. Dans cette optique de recherche de nouveaux matériaux, notre intérêt s est porté sur la phase Na3Fe3(PO4)4 et sur des monophosphates de fer et de manganèse de type alluaudite LiXNa1-XMnFe2(PO4)3. Leurs structures, respectivement en couche et en chaines, en font de bons candidats pour des applications en tant que matériau d électrode pour des batteries au lithium ou au sodium. Notre étude porte donc, d une part, sur la synthèse et la caractérisation structurale de ces phases, et d autre part sur leurs propriétés physiques et électrochimiques.Since the discovery of highly interesting properties for LiFePO4 as a positive electrode material in lithium ion batteries, the search for novel polyanion-based insertion hosts is intense. Actually, cathodic materials based on iron phosphates exhibit high stability and economical and environmental interests. In this context, we were interested in Na3Fe3(PO4)4 with a lamellar structure and in alluaudite-like iron and manganese phosphates LiXNa1-XMnFe2(PO4)3 which structure exhibits tunnels. This work deals, in one hand, on the synthesis and the structural characterisation of these materials and in the other hand on their physical and electrochemical properties as positive electrode for lithium and sodium batteries.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF