An arsenate with the α-CrPO4 structure type, NaCa1–x Ni3–2x Al2x (AsO4)3 (x = 0.23): crystal structure, charge-distribution and bond-valence-sum analyses

2017 ◽  
Vol 73 (11) ◽  
pp. 896-904 ◽  
Author(s):  
Ridha Ben Smail ◽  
Mohamed Faouzi Zid
Keyword(s):  
Crystal Structure ◽  
Charge Distribution ◽  
Structural Model ◽  
Ionic Conduction ◽  
Three Dimensional ◽  
Structure Type ◽  
Bond Valence ◽  
Ion Conductor ◽  
X Ray ◽  
Bond Valence Sum

Since the discovery of electrochemically active LiFePO4, materials with tunnel and layered structures built up of transition metals and polyanions have become the subject of much research. A new quaternary arsenate, sodium calcium trinickel aluminium triarsenate, NaCa1–x Ni3–2x Al2x (AsO4)3 (x = 0.23), was synthesized using the flux method in air at 1023 K and its crystal structure was determined from single-crystal X-ray diffraction (XRD) data. This material was also characterized by qualitative energy-dispersive X-ray spectroscopy (EDS) analysis and IR spectroscopy. The crystal structure belongs to the α-CrPO4 type with the space group Imma. The structure is described as a three-dimensional framework built up of corner-edge-sharing NiO6, (Ni,Al)O6 and AsO4 polyhedra, with channels running along the [100] and [010] directions, in which the sodium and calcium cations are located. The proposed structural model has been validated by bond-valence-sum (BVS) and charge-distribution (CHARDI) tools. The sodium ionic conduction pathways in the anionic framework were investigated by means of the bond-valence site energy (BVSE) model, which predicted that the studied material will probably be a very poor Na+ ion conductor (bond-valence activation energy ∼7 eV).

scholarly journals K1+2xNi1−xFe2(AsO4)3(x= 0,125): un nouvel arséniate à structure de type α-CrPO4

2017 ◽  
Vol 73 (2) ◽  
pp. 239-245 ◽  
Author(s):  
Ridha Ben Smail ◽  
Mohamed Faouzi Zid
Keyword(s):  
Crystal Structure ◽  
Structural Model ◽  
Three Dimensional ◽  
Structure Type ◽  
X Ray Diffraction ◽  
Flux Method ◽  
X Ray ◽  
Eds Analysis ◽  
Madelung Energy ◽  
Bond Valence Sum

A new arsenate K1+2xNi1−xFe2(AsO4)3(x= 1/8) {potassium nickel diiron(III) tris[arsenate(V)]} was synthesized using a flux method and its crystal structure was determined from single-crystal X-ray diffraction data. This material was also characterized by qualitative energy dispersive X-ray spectroscopy (EDS) analysis. The crystal structure belongs to the α-CrPO4-structure type, space groupImma. It consists of a three-dimensional-framework built up from FeO6and Ni0.875□1.25O6-octahedra and AsO4-tetrahedra that are sharing corners and/or edges, generating tunnels running along the [010] and [001] directions in which the potassium cations are located. The proposed structural model was validated by bond-valence-sum calculations, charge-distribution (CHARDI) and Madelung energy analyses.

scholarly journals Crystal structure of KNaCuP2O7, a new member of the diphosphate family

2018 ◽  
Vol 74 (2) ◽  
pp. 109-112 ◽  
Author(s):  
Ines Fitouri ◽  
Habib Boughzala
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Charge Distribution ◽  
Structural Model ◽  
Interlayer Space ◽  
Structure Type ◽  
Solid State Reactions ◽  
Space Group ◽  
Potassium Sodium ◽  
Bond Valence Sum

Potassium sodium copper(II) diphosphate(V), KNaCuP2O7, was synthesized by solid-state reactions. It crystallizes in the α-Na2CuP2O7 structure type in space group P21/n. In the crystal, CuO5 square-pyramids are linked to nearly eclipsed P2O7 groups by sharing corners to build up corrugated layers with composition [CuP2O7]2− that extend parallel to (010). The K+ and Na+ cations reside in the interlayer space and are connected to nine and seven O atoms, respectively. The structural model was validated by bond-valence-sum (BVS) and charge-distribution (CHARDI) analysis.

scholarly journals Synthesis, crystal structure and charge-distribution validation of β-Na4Cu(MoO4)3adopting the alluadite structure-type

2016 ◽  
Vol 72 (8) ◽  
pp. 1103-1107 ◽  
Author(s):  
Wassim Dridi ◽  
Mohamed Faouzi Zid
Keyword(s):  
Charge Distribution ◽  
Three Dimensional ◽  
Structure Type ◽  
Solid State Reactions ◽  
Site Symmetry ◽  
Structure Model ◽  
X Ray Diffraction ◽  
New Variety ◽  
X Ray ◽  
Bond Valence Sum

Single crystals of a new variety of tetrasodium copper(II) tris[molybdate(VI)], Na4Cu(MoO4)3, have been synthesized by solid-state reactions and characterized by single-crystal X-ray diffraction. This alluaudite structure-type is characterized by the presence of infinite layers of composition (Cu/Na)2Mo3O14parallel to the (100) plane, which are linked by MoO4tetrahedra, forming a three-dimensional framework containing two types of hexagonal channels in which Na+cations reside. The Cu2+and Na2+cations are located at the same general site with occupancies of 0.5. All atoms are on general positions except for one Mo, two Na (site symmetry 2) and another Na (site symmetry -1) atom. One O atom is split into two separate positions with occupancies of 0.5. The title compound is isotypic with Na5Sc(MoO4)4and Na3In2As3O12. The structure model is supported by bond-valence-sum (BVS) and charge-distribution CHARDI methods. β-Na4Cu(MoO4)3is compared and discussed with the K4Cu(MoO4)3and α-Na4Cu(MoO4)3structures.

scholarly journals Sodium dipotassium citrate, NaK2C6H5O7

2016 ◽  
Vol 72 (3) ◽  
pp. 403-406 ◽  
Author(s):  
Alagappa Rammohan ◽  
James A. Kaduk
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Density Functional ◽  
Three Dimensional ◽  
Bond Valence ◽  
Carboxylate Group ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Dimensional Network ◽  
Bond Valence Sum

The crystal structure of sodium dipotassium citrate, Na+·2K+·C6H5O73−, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The Na+and one of the K+cations are six-coordinate, with bond-valence sums of 1.13 and 0.92 valence units, respectively, while another crystallographically independent K+cation is seven-coordinate with a bond-valence sum of 1.20. The [KO6] and [KO7] polyhedra share edges and corners to form layers perpendicular to thebaxis. The distorted [NaO6] octahedra share edges to form chains along theaaxis. The result is a three-dimensional network. The only O—H...O hydrogen bond is an intramolecular one between the hydroxy group and a terminal carboxylate group.

scholarly journals Synthesis, crystal structure and charge-distribution validation of a new alluaudite-type phosphate, Na2.22Mn0.87In1.68(PO4)3

2020 ◽  
Vol 76 (8) ◽  
pp. 1369-1372
Author(s):  
Abdessalem Badri ◽  
Inmaculada Alvarez-Serrano ◽  
María Luisa López ◽  
Mongi Ben Amara
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Three Dimensional ◽  
Structure Type ◽  
X Ray Diffraction ◽  
Flux Method ◽  
X Ray ◽  
Coordination Numbers ◽  
Dimensional Network ◽  
Anionic Framework

Na2.22Mn0.87In1.68(PO4)3, sodium manganese indium tris(phosphate) (2.22/0.87/1.68), was obtained in the form of single crystals by a flux method and was structurally characterized by single-crystal X-ray diffraction. The compound belongs to the alluaudite structure type (space group C2/c) with general formula X(2)X(1)M(1)M(2)2(PO4)3. The X(2) and X(1) sites are partially occupied by sodium [occupancy 0.7676 (17) and 1/2] while the M(1) and M(2) sites are fully occupied within a mixed distribution of sodium/manganese(II) and manganese(II)/indium, respectively. The three-dimensional anionic framework is built up on the basis of M(2)2O10 dimers that share opposite edges with M(1)O6 octahedra, thus forming infinite chains extending parallel to [10\overline{1}]. The linkage between these chains is ensured by PO4 tetrahedra through common vertices. The three-dimensional network thus constructed delimits two types of hexagonal channels, resulting from the catenation of M(2)2O10 dimers, M(1)O6 octahedra and PO4 tetrahedra through edge- and corner-sharing. The channels are occupied by Na+ cations with coordination numbers of seven and eight.

scholarly journals Redetermination of Mg2B25 based on single-crystal X-ray data

2012 ◽  
Vol 68 (6) ◽  
pp. i50-i50 ◽  
Author(s):  
Luca Bindi ◽  
Alessandro Figini Albisetti ◽  
Giovanni Giunchi ◽  
Luciana Malpezzi ◽  
Norberto Masciocchi
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Data ◽  
Structural Model ◽  
Structure Type ◽  
Site Symmetry ◽  
Metal Boride ◽  
X Ray Diffraction ◽  
X Ray ◽  
Anisotropic Displacement Parameters

The crystal structure of Mg2B25, dimagnesium pentaeicosaboride, was reexamined from single-crystal X-ray diffraction data. The structural model previously reported on the basis of powder X-ray diffraction data [Giunchi et al. (2006). Solid State Sci. 8, 1202–1208] has been confirmed, although a much higher precision refinement was achieved, leading to much smaller standard uncertainties on bond lengths and refined occupancy factors. Moreover, all atoms were refined with anisotropic displacement parameters. Mg2B25 crystallizes in the β-boron structure type and is isostructural with other rhombohedral compounds of the boron-rich metal boride family. Magnesium atoms are found in interstitial sites on special positions (two with site symmetry .m, one with .2 and one with 3m), all with partial occupancies.

Crystal structure of lanthanum oxyorthosilicate, La2SiO5

2006 ◽  
Vol 21 (4) ◽  
pp. 300-303 ◽  
Author(s):  
Koichiro Fukuda ◽  
Tomoyuki Iwata ◽  
Eric Champion
Keyword(s):  
Crystal Structure ◽  
Structural Model ◽  
Rietveld Method ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Reliability Indices ◽  
Volumetric Expansion ◽  
Tricapped Trigonal Prism

The crystal structure of La2SiO5 was refined from laboratory X-ray powder diffraction data (CuKα1) using the Rietveld method. The crystal structure is monoclinic (space group P21∕c,Z=4) with lattice dimensions a=0.93320(2) nm, b=0.75088(1) nm, c=0.70332(1) nm, β=108.679(1)°, and V=0.46687(1) nm3. The final reliability indices were Rwp=7.14%, RP=5.52%, and RB=3.83%. There are two La sites in the structural model, La1 and La2. La1 is ninefold coordinated to oxygen, forming a tricapped trigonal prism with a mean La1-O distance of 0.263 nm. The La2O7 coordination polyhedron is a distorted capped octahedron with a mean La2-O distance of 0.251 nm. The La1O9 polyhedra share faces and the La2O7 polyhedra share edges, forming two sets of sheets that alternate parallel to the (100) plane. These sheets are linked through SiO4 tetrahedra and non-silicon-bonded oxygen atoms to form a three-dimensional structure. This compound is isomorphous with the low-temperature (X1) phases of R2SiO5 (R=Y and Gd). The volumes of RO9 polyhedra steadily increase with increasing ionic radius of R, from Y3+ to Gd3+ to La3+, which causes substantial volumetric expansion of the crystals.

The crystal structure of the first synthetic copper(II) tellurite arsenate, CuII 5(TeIVO3)2(AsVO4)2

2020 ◽  
Vol 76 (1) ◽  
pp. 1-6
Author(s):  
Owen P. Missen ◽  
Matthias Weil ◽  
Stuart J. Mills ◽  
Eugen Libowitzky
Keyword(s):  
Crystal Structure ◽  
Three Dimensional ◽  
Chemical Vapour ◽  
Structure Type ◽  
Void Space ◽  
X Ray Diffraction ◽  
X Ray ◽  
Novel Structure ◽  
Jahn Teller ◽  
Transport Method

Crystals of the first synthetic copper tellurite arsenate, CuII 5(TeIVO3)2(AsVO4)2 [systematic name pentacopper(II) bis-oxotellurate(IV) bis-oxoarsenate(V)], were grown by the chemical vapour transport method and structurally determined using single-crystal X-ray diffraction. CuII 5(TeIVO3)2(AsVO4)2 possesses a novel structure type including a new topological arrangement of CuII and O atoms. CuII 5(TeIVO3)2(AsVO4)2 is formed from a framework of two types of Jahn–Teller distorted [CuIIO6] octahedra (one of which is considerably elongated) and [CuIIO5] square pyramids, which are linked by edge-sharing to form chains and dimers and by corner-sharing to complete a three-dimensional framework. [AsVO4] tetrahedra and [TeIVO5] polyhedra bridge the edges of channels along the a-axis direction, with void space remaining for the TeIV stereoactive 5s 2 lone pairs. A comparison is made between the crystal structure of CuII 5(TeIVO3)2(AsVO4)2 and those of known compounds and minerals, in particular fumarolitic Cu minerals.

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