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 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

Crystal structure, Mössbauer spectroscopy and dye adsorption properties of a new layered iron phosphate RbMgFe(PO4)2

Materials based on inorganic phosphates, in particular iron monophosphates, exhibited significant applications in multiple fields due to their structural chemistry. In the present work, the synthesis of a new compound expressed as RbMgFe(PO4)2 was described using flux and solid state methods. The resulting product was analyzed by X-ray diffraction (XRD), Mössbauer and FT-IR spectroscopy and DR UV–vis. It crystallized in the trigonal system (space group P-3m1) with the cell parameters: a = 5.473(2) Å, c = 8.116(3) and Z = 1. Its structure was formed by isolated (Fe, Mg)O4 and PO4 tetrahedra shares vertices to form layers parallel to the ab plane. The Rb+ cations were located in interlayer space. The IR spectrum confirmed the presence of only PO4 group. The distribution of iron and its oxidation state and local environments were confirmed by Mössbauer spectroscopy. The ability of RbMgFe(PO4)2 to adsorb a cationic dye (Methylene Blue) was carried out under the variation of some experimental conditions (pH, concentration, duration and temperature). The adsorption process was chemical and favorable as proved by the data modeling along pseudo second order and both Langmuir and Freundlich theoretical equations

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

Structural study and physical properties of a new phosphate KCuFe(PO₄)₂

Single crystals of a new phosphate KCuFe(PO4)2 have been prepared by the flux method and its structural and physical properties have been investigated. This compound crystallizes in the monoclinic system with the space group P21/n and its parameters are: a=7.958(3) Å, b=9.931(2) Å, c=9.039(2) Å, β=115.59(3)° and Z=4. Its structure consists of FeO6 octahedra sharing corners with Cu2O8 units of edge-sharing CuO5 polyhedra to form undulating chains extending infinitely along the b-axis. These chains are connected by the phosphate tetrahedra giving rise to a 3D framework with six-sided tunnels parallel to the [101] direction, where the K+ ions are located. The Mössbauer spectroscopy results confirm the exclusive presence of octahedral Fe3+ ions. The magnetic measurements show the compound to be antiferromagnetic with Cm=5.71 emu K/mol and θ=−156.5 K. The derived experimental effective moment μex=6.76μB is somewhat higher than the theoretical one of μth=6.16μB, calculated taking only into account the spin contribution for Fe3+ and Cu2+ cations. Electrical measurements allow us to obtain the activation energy (1.22 eV) and the conductivity measurements suggest that the charge carriers through the structure are the potassium cations

Crystal structure, IR and Mössbauer spectroscopy and magnetic properties of KZnFe(PO4)2 related to the zeolite-ABW-like compounds

The new iron phosphate KZnFe(PO4)2 has been synthesized by flux method and solid state reaction, and characterized by X-ray diffraction, IR, Mössbauer spectroscopy and magnetic susceptibility. This compound crystallizes in the monoclinic space group C2/c with the cell parameters: a = 13.514(4) Å, b = 13.273(6) Å, c = 8.742(3) Å and β = 100.07(2)°. It displays strong similarities with the phosphates KCoAl(PO4)2 and NaCoPO4 and features some analogies with the zeolite-ABW structural type. 3D framework is built up by a corner-sharing between MO4 (M = 0.5 Zn + 0.5 Fe) and PO4 tetrahedra. The K+ ions are found within crossing tunnels perpendicular to the (1 0 0), (0 1 0) and (0 0 1) planes, delimited by this framework. A Mössbauer study confirmed the presence of Fe3+ ions in a tetrahedral environment. Magnetic measurements revealed an antiferromagnetic behavior with TN = 8.5 K

The layered iron phosphate KMgFe(PO₄)₂: Crystal structure, Mössbauer spectroscopy and ionic conductivity

A new iron phosphate, KMgFe(PO4)2 has been synthesized and investigated by X-ray diffraction, Mössbauer spectroscopy and ionic conductivity. This compound crystallizes in the monoclinic space group C2/c with the parameters a = 18.529(7) Å, b = 5.402(3) Å, c = 9.374(9) Å, β = 120.64(5)° and Z = 4. Its original structure can be described as the stacking along the [101] direction of [MgFe(PO4)−2]∞ layers of corner-sharing MO4 (M = 0.5 Fe + 0.5 Mg) and PO4 tetrahedra. The K+ ions are occupying the inter-layer space. The Mössbauer spectroscopy confirms the occurrence of only tetrahedral Fe3+ ions and gives a definitive proof of the disordered character of their distribution. Ionic conductivity results obtained by the impedance spectroscopy technique show that this material is a two-dimensional ionic conductor, with low activation energy, 0.51 eV, that is interpreted on the basis of two-dimensional pathways

Crystal structure and thermal stability of new iron phosphates KMFe(PO4)2 (M = Ni, Mg, and Co)

Three isostructural iron monophosphates KNiFe(PO4)2 (KNi), KMgFe(PO4)2 (KMg-LT, where LT means “low-temperature stable phase”), and KCoFe(PO4)2 (KCo-LT) are synthesized and structurally characterized from X-ray diffraction data. They crystallize in the monoclinic system with the space group P21/c. Their structures have in common a three-dimensional framework, built up by infinite zigzag chains of edge-sharing MO6 (M = Ni, Mg or Co) octahedra, linked by FeO5 and PO4 polyhedra via vertices and edges to form a rigid skeleton. The K+ ions are located in formed tunnels. DTA showed that KNi has a congruent melting at 941°C, whereas KMg-LT and KCo-LT undergo irreversible phase transitions from P21/c to different high-temperature structures with the C 2/c symmetry. IR absorption bands are assigned to different vibrations of the PO4 tetrahedron

Synthesis and characterization of a novel alkali mixed magnesium-aluminum phosphate with a layered structure–KMgAl(PO4)2

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