Mongi Ben Amara

Na2BaMg(PO4)2: synthesis, crystal structure and europium photoluminescence properties

Na2BaMg(PO4)2 was synthesized and characterized by X-ray diffraction, differential thermal analysis (DTA), 31P NMR spectroscopy and photoluminescence measurements. This compound crystallized in the P 3¯m1 space group of the trigonal system with the parameters of equivalent hexagonal cell a=0.5305(1) nm and c=0.6986(3) nm. The structure showed a perfect isotipysm with the mineral glaserite K3Na(SO4)2. Thus, it exhibited a lamellar framework which could be described as the stacking along the [001] direction of [MgP2O84−]∞ layers of corner sharing MgO6 polyhedra and PO4 tetrahedra. The Ba2+ cations were located within the interlayer space, while the Na+ ones were found in large cavities bound to the layers. The DTA analysis showed that this compound melt congruently at 1385 K. The 31P NMR spectrum was consistent with the presence of a single phosphorus site in the structure. Optical properties were investigated for the 5% doped Eu3+ and Eu2+ phases. The trivalent europium was used as a local probe, replacing barium while the divalent europium was used to examine whether this material could be used as an optical applications.

The iron phosphate NaZnFe2(PO4)3

Crystals of sodium zinc diiron(III) triphosphate, NaZnFe(2)(PO(4))(3), have been synthesized and structurally characterized by single-crystal X-ray diffraction. The compound features a new structural type built up from ZnO(6) octahedra, FeO(6) octahedra and FeO(4) tetrahedra, linked together via the corners and edges of PO(4) tetrahedra to form a three-dimensional framework, with tunnels running along [100]. Within these tunnels, Na(+) cations occupy a highly distorted cubic site.

The iron phosphate K3Fe5(PO4)6

The crystal structure of tripotassium pentairon hexaphosphate has been determined by single-crystal X-ray diffraction. The structure contains one Fe atom on a center of symmetry, one K, two Fe and two P atoms on twofold axes, and one Fe, two P and one K atom in general positions. The K(3)Fe(5)(PO(4))(6) structure consists of a complex three-dimensional framework of corner-sharing between iron polyhedra, and corner- and edge-sharing between PO(4) tetrahedra and iron polyhedra (FeO(5) and FeO(6)). This linkage between iron and phosphorus forms intersecting channels containing the K atoms.