No abstract

A new phosphate, sodium calcium magnesium tetrakis(phosphate), Na(8)Ca(1.5)Mg(12.5)(PO(4))(12), has been synthesized by a flux method. Its novel structure consists of MgO(x) (x = 5 and 6) polyhedra and MO(7) (M = Mg or Na) octahedra linked directly through common corners or edges to form a rigid three-dimensional skeleton, reinforced by corner-sharing between identical Mg(12)MO(48) units. The connection of these units by the PO(4) tetrahedra induces cavities and crossing tunnels where the Na(+) and Ca(2+) cations are located. This structural model was supported by a (31)P NMR spectroscopy study which confirmed the existence of 12 crystallographically independent sites for the P atoms.

The compound is characterized by single crystal XRD and 31 P NMR spectroscopy. It crystallizes in the monoclinic space group P21/n with Z = 4. The structure consists of MgO x (x = 5, 6) and MO 7 (M: Mg, Na) polyhedra linked through common corners or edges to form a rigid three-dimensional skeleton, reinforced by corner--sharing between identical Mg12MO48 units. These units are connected by PO4 tetrahedra forming cavities and crossing tunnels in which the Na + and Ca 2+ cations are located. -(JERBI, H.; HIDOURI*, M.; RZEIGUI, M.; BEN AMARA, M.; Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 67 (2011) 3, i17-i20, http://dx.doi.org/10.1107/s0108270110054521 ; Fac. Sci., Univ. Monastir, 5019 Monastir, Tunisia; Eng.) -W. Pewestorf 25-002