A sodium calcium arsenate, NaCa(AsO4)
نویسندگان
چکیده
The title compound, NaCa(AsO(4)), was synthesized using a hydro-thermal method at 633-643 K. It has a dense structure composed of alternating layers of distorted [CaO(6)] octa-hedra and layers of [AsO(4)] tetra-hedra and distorted [NaO(6)] octa-hedra, stacked along the a axis. The As, Ca and two O atoms lie on the mirror plane at y = 1/4 (i.e. 4c), while the Na atom lies on an inversion centre (1/2, 1/2, 0) (i.e. 4b). Each distorted [CaO(6)] octa-hedron shares four equatorial common O vertices with four neighboring octa-hedra, forming a layer parallel to (100), whereas each distorted [NaO(6)] octa-hedron shares two opposite edges with two neighboring ones, forming a chain running along [010]. Each isolated [AsO(4)] tetra-hedron shares two edges with two different [NaO(6)] octa-hedra in one [NaO(6)] chain and a vertex with another chain. Simultaneously the above [AsO(4)] tetra-hedron located in a four-membered [CaO(6)] ring shares one edge of its base facet with one [CaO(6)] octa-hedron and three corners with three other [CaO(6)] octa-hedra of one [CaO(6)] layer, and the remaining apex is shared with another [CaO(6)] layer. [NaO(6)] octa-hedra and [CaO(6)] octa-hedra are linked to each other by sharing edges and vertices.
منابع مشابه
The alluaudite-like arsenate NaCaMg3(AsO4)3
The title compound, sodium calcium trimagnesium tris-(arsenate), an alluaudite-like arsenate, was prepared by solid-state reaction at high temperature. The structure is built up from edge-sharing MgO(6) octa-hedra in chains associated with the AsO(4) arsenate groups. The three-dimensional network leads to two different tunnels occupied statistically by Na(+) and Ca(2+). One As and one Mg atom l...
متن کاملMicroscale Investigation of Arsenic Distribution and Species in Cement Product from Cement Kiln Coprocessing Wastes
To improve the understanding of the immobilization mechanism and the leaching risk of Arsenic (As) in the cement product from coprocessing wastes using cement kiln, distribution and species of As in cement product were determined by microscale investigation methods, including electron probe microanalysis (EPMA) and X-ray absorption spectroscopy. In this study, sodium arsenate crystals (Na3AsO41...
متن کاملCrystal Structure of the Arsenate(V) NaTi2[AsO4]3
The arsenate(V) NaTi2[AsO4]3 has been synthesized by a solid-state reaction route using a salt flux. Its structure has been solved and refined from single-crystal X-ray data: NASICON-type, R3̄c, a = 8.8057(5), c = 22.2406(15) Å, Z = 6, wR(F2) = 0.0617 for 576 unique reflections and 30 variables. The NaTi2[AsO4]3 structure consists of a three-dimensional framework of corner-sharing AsO4 tetrahedr...
متن کاملStructural characterization and vibrational spectroscopy of the arsenate mineral wendwilsonite.
In this paper, we have investigated on the natural wendwilsonite mineral with the formulae Ca2(Mg,Co)(AsO4)2⋅2(H2O). Raman spectroscopy complimented with infrared spectroscopy has been used to determine the molecular structure of the wendwilsonite arsenate mineral. A comparison is made with the roselite mineral group with formula Ca2B(AsO4)2⋅2H2O (where B may be Co, Fe(2+), Mg, Mn, Ni, Zn). The...
متن کاملCharacterization of Arsenate-for-sulfate Substitution in Synthetic Jarosite Using X-ray Diffraction and X-ray Absorption Spectroscopy
Arsenic-bearing synthetic jarosite [KFe3(SO4)2(OH)6] was characterized to elucidate the form of the arsenic. The XANES spectra indicate that the As occurs exclusively as As5+, nominally as AsO4, consistent with the valence state of the arsenic in the reagents used for the syntheses. X-ray-diffraction analyses show that at least 9.9 wt.% AsO4 can be structurally incorporated in the jarosite. Cel...
متن کامل