Abstract. Rubidium aluminium pyroarsenate, Mr = 374.29, triclinic, Pi, a = 8.233 (5), b = 6.34 (2), c = 6.241 (5) tk, a = 102.6(1), fl = 103.89(7), y= 96.7 (1) °, V = 303.9 A 3, Z = 2, D,, = 3.9 (3) (pycnometry), Dx --4.09 g cm-3, a(Ag K~) = 0.5608A,, #=108.14cm-1, F(000)=344, T= 296 K, R = 0.049, wR = 0.053 for 2193 reflections.The first structural investigation on a pyroarsenate is reported. It is built from A1As20~I units comprising one A106 octahedron and one As207 pyroarsenate group in which two AsO4 tetrahedra point in opposite directions. These units are connected by heteropolyhedral linkages to form a three-dimensional framework having intersecting tunnels where the Rb + ions are located. Although this structure is not isotypic with the phosphate analogues, it is closely related to that of the pyrophosphates of type I represented by KAIP207.
Iron I 7100The Iron Potassium Diarsenate KFeAs2O7 Structural, Electric and Magnetic Behaviors. -Single crystals of the new title compound are prepared from aqueous mixtures of KNO3, Fe(NO3)3, and H3AsO4 with a K:Fe:As molar ratio of 1:0.1:2 (evaporation, 400°C for 24 h, 700°C for 3 h). KFeAs2O7 crystallizes in the triclinic space group P1 with Z = 4 (single crystal XRD). The structure consists of corner-sharing FeO6 octahedra and As2O7 groups. The K + ions reside in tunnels of the three-dimensional framework. Impedance measurements show that KFeAs 2 O 7 is an ionic conductor with a conductivity of 2.76·10 -7 S/cm at 568 K. Magnetic measurements reveal Curie-Weiss paramagnetic behavior over the range 30-300 K and ferromagnetic behavior below 29.3 K. -(OUERFELLI, N.; GUESMI*, A.; MOLINIE, P.; MAZZA, D.; ZID, M. F.; DRISS, A.; J. Solid State
Key indicators: single-crystal X-ray study; T = 298 K; mean (As-O) = 0.004 Å; disorder in main residue; R factor = 0.026; wR factor = 0.068; data-to-parameter ratio = 10.0.The title compound, tetrasodium lithium cobalt aluminium hexa(orthoarsenate), was synthesized by a solid state reaction route. In the crystal structure, Co 2+ ions are partially substituted by Al 3+ in an octahedral environment [M1 with site symmetry 2/m; occupancy ratio Co:Al = 0.286 (10) The anionic unit is formed by two octahedra and three tetrahedra linked only by corners. The CoM1M2As 2 O 19 units associate to an open three-dimensional framework containing tunnels propagating along the a-axis direction. One Na + cation is located in the periphery of the tunnels while the other two are situated in the centres: all Na + cations exhibit halfoccupancy. The structure of the studied material is compared with those of various related minerals reported in the literature.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.