Olivine-type NaCd(AsO4).
Ontology highlight
ABSTRACT:
SUBMITTER: Weil M
PROVIDER: S-EPMC3884235 | biostudies-literature | 2013 Oct
REPOSITORIES: biostudies-literature
Publications
Olivine-type NaCd(AsO4).
Acta crystallographica. Section E, Structure reports online 20131005 Pt 11
The title compound, sodium cadmium orthoarsenate, adopts the olivine [Mg2(SiO4)] structure type in space group Pnma, with Na (site symmetry -1) and Cd (.m.) replacing the two Mg positions, and the AsO4 tetra-hedron (.m.) the SiO4 tetra-hedron. The crystal structure is made up of a nearly hexa-gonal closed-packed arrangement of O atoms stacked along [001]. The Na and Cd atoms occupy one half of the octa-hedral voids in alternate layers stacked along [100], and one eighth of the tetra-hedral voids ...[more]
Similar Datasets
Project description: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 octa-hedral environment [M1 with site symmetry 2/m; occupancy ratio Co:Al = 0.286?(10):0.714?(10)]. The charge compensation is ensured by Li(+) cations sharing a tetra-hedral site with Co(2+) ions [M2 with site symmetry 2; occupancy ratio Co:Li = 0.690?(5):0.310?(5)]. The anionic unit is formed by two octa-hedra and three tetra-hedra linked only by corners. The CoM1M2As2O19 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 half-occupancy. The structure of the studied material is compared with those of various related minerals reported in the literature.
| S-EPMC3790335 | biostudies-literature
Project description:A new compound with a non-centrosymmetric structure, potassium tetra-kis-[dioxomolybdenum(IV)] arsenate trioxide, K(MoO2)4O3(AsO4), has been synthesized by a solid-state reaction. The [(MoO2)4O3(AsO4)](+) three-dimensional framework consists of single arsenate AsO4 tetra-hedra, MoO6 octa-hedra, MoO5 bipyramids and bi-octa-hedral units of edge-sharing Mo2O10 octa-hedra. The [Mo2O8]∞ octa-hedral chains running along the a-axis direction are connected through their corners to the AsO4 tetra-hedra, MoO6 octa-hedra and MoO5 bipyramids, so as to form large tunnels propagating along the a axis in which the K(+) cations are located. This structure is compared with compounds containing M 2O10 (M = Mo, V, Fe) dimers and with those containing M 2O8 (M = V) chains.
| S-EPMC3684866 | biostudies-literature
Project description:The title compound, sodium potassium trialuminium tetra-kis-(orthoarsenate), was prepared by solid-state reactions. The anionic framework consists of corrugated layers parallel to (010) and is made up of corner-sharing AlO6 octa-hedra (site symmetries .2. and 2/m..) that are connected to isolated AsO4 tetra-hedra (site symmetries .2. and m..) through edge- and corner-sharing. The alkali cations are occupationally disordered. The two K(+) cations [site symmetries .2. and m..; occupancies 0.314?(7) and 0.035?(12)] are situated in the inter-layer space, whereas the smaller Na(+) cations [both with site symmetry m..; occupancies = 0.725?(14) and 0.112?(14)] are located in the cavities of the anionic framework. The K(+) cations are surrounded by six and seven O atoms, the Na(+) cations by seven and nine O atoms. The resulting coordination polyhedra of the two types of cations are highly distorted.
| S-EPMC3914036 | biostudies-literature
Project description:The sintering behaviour of several green compacts made with olivine or olivine/alumina powder blends has been examined. To this goal, powders were attrition milled, uniaxially pressed into specimens and air sintered at temperatures ranging from 1100 to 1300 °C. The resulting samples were characterized by water absorption, shrinkage, phase composition and density. Compositions containing 5%, 10% and 20% Al₂O₃ have a sintering behaviour similar to that of olivine alone, reaching low residual porosity when fired at 1300 °C. Conversely, the composition containing 40% Al₂O₃ displays an almost flat shrinkage profile and maintains high residual porosity in the examined temperature range.
| S-EPMC5455912 | biostudies-other
Project description:The title compound, tetra-sodium hepta-nickel hexa-arsenate, was obtained by ceramic synthesis and crystallizes in the monoclinic space group C2/m. The asymmetric unit contains seven Ni atoms of which two have site symmetry 2/m and three site symmetry 2, four As atoms of which two have site symmetry m and two site symmetry 2, three Na atoms of which two have site symmetry 2, and fifteen O atoms of which four have site symmetry m. The structure of Na4Ni7(AsO4)6 is made of layers of Ni octa-hedra and As tetra-hedra assembled in sheets parallel to the bc plane. These layers are inter-connected by corner-sharing between NiO6 octa-hedra and AsO4 tetra-hedra. This linkage creates tunnels running along the c axis in which the Na atoms are located. This arrangement is similar to the one observed in Na4Ni7(PO4)6, but the layers of the two compounds are slightly different because of the disorder of one of the Ni sites in the structure of the title compound.
| S-EPMC4908513 | biostudies-literature
Project description:In this study, a layered olivine-type LiMnPO4/functionalized-multiwall carbon nanotube (f-MWCNTs) composite is used as an electrochemically active material for the real-time detection of dopamine. A wet-chemical ultrasonication process is used to combine LiMnPO4 with f-MWCNTs at room temperature. The composite was subjected to various structural, morphological and electrochemical studies. The blending of olivine-type LiMnPO4 into the f-MWCNTs is revealed by TEM analysis. The electrochemical activities of the LiMnPO4/f-MWCNTs composite are systematically investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) for the real-time detection of dopamine. Furthermore, the applicability of the as prepared LiMnPO4/f-MWCNTs composite was extended for the detection of human serum (E48) and rat brain-serum (C7) samples with satisfactory recoveries for the real-time applications. All these studies revealed that the layered olivine-type LiMnPO4/f-MWCNTs composite is a potential candidate in the field of electrochemical sensing.
| S-EPMC9083883 | biostudies-literature
Project description:Agardite-(Y), with a refined formula of Cu(2+) 5.70(Y0.69Ca0.31)[(As0.83P0.17)O4]3(OH)6·3H2O [ideally Cu(2+) 6Y(AsO4)3(OH)6·3H2O, hexa-copper(II) yttrium tris-(arsenate) hexa-hydroxide trihydrate], belongs to the mixite mineral group which is characterized by the general formula Cu(2+) 6 A(TO4)3(OH)6·3H2O, where nine-coordinated cations in the A-site include rare earth elements along with Al, Ca, Pb, or Bi, and the T-site contains P or As. This study presents the first structure determination of agardite-(Y). It is based on the single-crystal X-ray diffraction of a natural sample from Jote West mine, Pampa Larga Mining District, Copiapo, Chile. The general structural feature of agardite-(Y) is characterized by infinite chains of edge-sharing CuO5 square pyramids (site symmetry 1) extending down the c axis, connected in the ab plane by edge-sharing YO9 polyhedra (site symmetry -6..) and corner-sharing AsO4 tetra-hedra (site symmetry m..). Hy-droxyl groups occupy each corner of the CuO5-square pyramids not shared by a neighboring As or Y atom. Each YO9 polyhedron is surrounded by three tubular channels. The walls of the channels, parallel to the c axis, are six-membered hexa-gonal rings comprised of CuO5 and AsO4 polyhedra in a 2:1 ratio, and contain free mol-ecules of lattice water.
| S-EPMC3884410 | biostudies-literature
Project description:Meteorites from interplanetary space often include high-pressure polymorphs of their constituent minerals, which provide records of past hypervelocity collisions. These collisions were expected to occur between kilometre-sized asteroids, generating transient high-pressure states lasting for several seconds to facilitate mineral transformations across the relevant phase boundaries. However, their mechanisms in such a short timescale were never experimentally evaluated and remained speculative. Here, we show a nanosecond transformation mechanism yielding ringwoodite, which is the most typical high-pressure mineral in meteorites. An olivine crystal was shock-compressed by a focused high-power laser pulse, and the transformation was time-resolved by femtosecond diffractometry using an X-ray free electron laser. Our results show the formation of ringwoodite through a faster, diffusionless process, suggesting that ringwoodite can form from collisions between much smaller bodies, such as metre to submetre-sized asteroids, at common relative velocities. Even nominally unshocked meteorites could therefore contain signatures of high-pressure states from past collisions.
| S-EPMC8280208 | biostudies-literature
Project description:A well-preserved, ancient delta deposit, in combination with ample exposures of carbonate outcrops, makes Jezero Crater in Nili Fossae a compelling astrobiological site. We use Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) observations to characterize the surface mineralogy of the crater and surrounding watershed. Previous studies have documented the occurrence of olivine and carbonates in the Nili Fossae region. We focus on correlations between these two well-studied lithologies in the Jezero crater watershed. We map the position and shape of the olivine 1 ?m absorption band and find that carbonates are found in association with olivine which displays a 1 ?m band shifted to long wavelengths. We then use Thermal Emission Imaging Spectrometer (THEMIS) coverage of Nili Fossae and perform tests to investigate whether the long wavelength shifted (redshifted) olivine signature is correlated with high thermal inertia outcrops. We find that there is no consistent correlation between thermal inertia and the unique olivine signature. We discuss a range of formation scenarios for the olivine and carbonate associations, including the possibility that these lithologies are products of serpentinization reactions on early Mars. These lithologies provide an opportunity for deepening our understanding of early Mars and, given their antiquity, may provide a framework to study the timing of valley networks and the thermal history of the Martian crust and interior from the early Noachian to today.
| S-EPMC7592698 | biostudies-literature
Project description:Geoengineering is a proposed action to manipulate Earth's climate in order to counteract global warming from anthropogenic greenhouse gas emissions. We investigate the potential of a specific geoengineering technique, carbon sequestration by artificially enhanced silicate weathering via the dissolution of olivine. This approach would not only operate against rising temperatures but would also oppose ocean acidification, because it influences the global climate via the carbon cycle. If important details of the marine chemistry are taken into consideration, a new mass ratio of CO(2) sequestration per olivine dissolution of about 1 is achieved, 20% smaller than previously assumed. We calculate that this approach has the potential to sequestrate up to 1 Pg of C per year directly, if olivine is distributed as fine powder over land areas of the humid tropics, but this rate is limited by the saturation concentration of silicic acid. In our calculations for the Amazon and Congo river catchments, a maximum annual dissolution of 1.8 and 0.4 Pg of olivine seems possible, corresponding to the sequestration of 0.5 and 0.1 Pg of C per year, but these upper limit sequestration rates come at the environmental cost of pH values in the rivers rising to 8.2. Open water dissolution of fine-grained olivine and an enhancement of the biological pump by the rising riverine input of silicic acid might increase our estimate of the carbon sequestration, but additional research is needed here. We finally calculate with a carbon cycle model the consequences of sequestration rates of 1-5 Pg of C per year for the 21st century by this technique.
| S-EPMC2996662 | biostudies-literature