title: Structural features of two novel alluaudite-like arsenates Cd1.16Zn2.34(AsO4)1.5(HAsO4)(H2AsO4)0.5and Cd0.74Mg2.76(AsO4)1.5(HAsO4)(H2AsO4)0.5.
abstract: Two new compounds, Cd1.16Zn2.34(AsO4)1.5(HAsO4)(H2AsO4)0.5(1) and Cd0.74Mg2.76(AsO4)1.5(HAsO4)(H2AsO4)0.5(2), have been prepared hydrothermally. Their crystal structures consist of chains of edge-sharingM1O4(OH0.5)2,M1aO4(OH0.5)2,M2O5(OH0.5), andM2aO5(OH0.5) octahedra (M1,M1a= Zn, Cd;M2,M2a= Zn for1, andM1,M1a= Mg, Cd;M2,M2a= Mg for2) that are stacked parallel to (1 0 1) and are connected by the [(AsO4)0.5(AsO3(OH))0.5]2.5-and [(AsO4)0.5(AsO2(OH)2)0.5]2-tetrahedra. These chains produce two types of channels parallel to thec-axis. Cd atoms are located in channels 2, while in channels 1 are situated hydrogen atoms of OH groups. The infrared spectra clearly show the presence of broad O-H stretching and bending vibrations centred at 3236, 2392 1575 and 1396 cm-1in (1), and 3210, 2379 1602 and 1310 cm-1in (2). The O-H stretching frequency is in good agreement with O⋯O distances. Furthermore, structural characteristics of compounds with similar alluaudite-like structures were discussed.
authors.affiliation: Institute for Technology of Nuclear and Other Mineral Raw Materials, Applied Mineralogy Unit, Franchet d'Esperey 86, P.O. Box 390, 11000 Belgrade, Serbia.
authors.forename: Jovica
authors.initials: J
authors.lastname: Stojanović
authors.forename: Tamara
authors.initials: T
authors.lastname: Dorđević
authors.forename: Ljiljana
authors.initials: L
authors.lastname: Karanović
keywords: Chemical synthesis; Crystal structure; Inorganic materials; X-ray diffraction