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Crystal structure of a sodium, zinc and iron(III)-based non-stoichiometric phosphate with an alluaudite-like structure: Na1.67Zn1.67Fe1.33(PO4)3.

Khmiyas J, Assani A, Saadi M, El Ammari L - Acta Crystallogr E Crystallogr Commun (2015)

Bottom Line: The chains are formed by a succession of trimers based on [ZnO6] octa-hedra and the mixed-cation Fe(III)/Zn(II) [(Fe/Zn)O6] octa-hedra [Fe(III):Zn(III) ratio 0.668 (3)/0.332 (3)].Each Na(+) cation is coordinated by eight O atoms.The disorder of Na in the tunnel might presage ionic mobility for this material.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratoire de Chimie du Solide Appliquée, Faculté des Sciences, Université Mohammed V, Avenue Ibn Battouta, BP 1014, Rabat, Morocco.

ABSTRACT
The new title compound, disodium dizinc iron(III) tris-(phosphate), Na1.67Zn1.67Fe1.33(PO4)3, which belongs to the alluaudite family, has been synthesized by solid-state reactions. In this structure, all atoms are in general positions except for four, which are located on special positions of the C2/c space group. This structure is characterized by cation substitutional disorder at two sites, one situated on the special position 4e (2) and the other on the general position 8f. The 4e site is partially occupied by Na(+) [0.332 (3)], whereas the 8f site is entirely filled by a mixture of Fe and Zn. The full-occupancy sodium and zinc atoms are located at the Wyckoff positions on the inversion center 4a (-1) and on the twofold rotation axis 4e, respectively. Refinement of the occupancy ratios, bond-valence analysis and the electrical neutrality requirement of the structure lead to the given composition for the title compound. The three-dimensional framework of this structure consists of kinked chains of edge-sharing octa-hedra stacked parallel to [10-1]. The chains are formed by a succession of trimers based on [ZnO6] octa-hedra and the mixed-cation Fe(III)/Zn(II) [(Fe/Zn)O6] octa-hedra [Fe(III):Zn(III) ratio 0.668 (3)/0.332 (3)]. Continuous chains are held together by PO4 phosphate groups, forming polyhedral sheets perpendicular to [010]. The stacked sheets delimit two types of tunnels parallel to the c axis in which the sodium cations are located. Each Na(+) cation is coordinated by eight O atoms. The disorder of Na in the tunnel might presage ionic mobility for this material.

No MeSH data available.


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A stack of layers perpendicular to the b axis, showing small tunnels along the [201] direction.
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fig3: A stack of layers perpendicular to the b axis, showing small tunnels along the [201] direction.

Mentions: The crystal structure of this phosphate compound consists of infinite kinked chains of two edge-sharing [Fe1/Zn1O6] octa­hedra leading to the formation of [(Fe1,Zn1)2O10] dimers that are connected by a common edge to [Zn2O6] octa­hedra, as shown in Fig. 2 ▶. These chains are linked by PO4 tetra­hedral groups, forming a stack of sheets perpendicular to [010] and alternating with sodium layers, as shown in Fig. 3 ▶, which reveal small tunnels along the [201] direction. The three-dimensional framework also encloses two types of large tunnels, in which the Na+ cations reside, as shown in Fig. 4 ▶. The site 4e centred on the first tunnel is partially occupied by Na1 [0.332 (3)], whereas Na2 occupies site 4a centred on the second tunnel. Each sodium atom is surrounded by eight oxygen atoms with Na1—O and Na2—O bond lengths in the ranges 2.448 (1)–2.908 (2) Å, and 2.324 (1)–2.901 (1) Å, respectively. The displacement ellipsoids of the partially occupied atom Na1 are rather larger than those of the rest of the atoms. Most probably this is due to the size of the channels, which allows atom Na1 to have more freedom. The disorder of Na in the tunnel may presage ionic mobility for this material.


Crystal structure of a sodium, zinc and iron(III)-based non-stoichiometric phosphate with an alluaudite-like structure: Na1.67Zn1.67Fe1.33(PO4)3.

Khmiyas J, Assani A, Saadi M, El Ammari L - Acta Crystallogr E Crystallogr Commun (2015)

A stack of layers perpendicular to the b axis, showing small tunnels along the [201] direction.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4459337&req=5

fig3: A stack of layers perpendicular to the b axis, showing small tunnels along the [201] direction.
Mentions: The crystal structure of this phosphate compound consists of infinite kinked chains of two edge-sharing [Fe1/Zn1O6] octa­hedra leading to the formation of [(Fe1,Zn1)2O10] dimers that are connected by a common edge to [Zn2O6] octa­hedra, as shown in Fig. 2 ▶. These chains are linked by PO4 tetra­hedral groups, forming a stack of sheets perpendicular to [010] and alternating with sodium layers, as shown in Fig. 3 ▶, which reveal small tunnels along the [201] direction. The three-dimensional framework also encloses two types of large tunnels, in which the Na+ cations reside, as shown in Fig. 4 ▶. The site 4e centred on the first tunnel is partially occupied by Na1 [0.332 (3)], whereas Na2 occupies site 4a centred on the second tunnel. Each sodium atom is surrounded by eight oxygen atoms with Na1—O and Na2—O bond lengths in the ranges 2.448 (1)–2.908 (2) Å, and 2.324 (1)–2.901 (1) Å, respectively. The displacement ellipsoids of the partially occupied atom Na1 are rather larger than those of the rest of the atoms. Most probably this is due to the size of the channels, which allows atom Na1 to have more freedom. The disorder of Na in the tunnel may presage ionic mobility for this material.

Bottom Line: The chains are formed by a succession of trimers based on [ZnO6] octa-hedra and the mixed-cation Fe(III)/Zn(II) [(Fe/Zn)O6] octa-hedra [Fe(III):Zn(III) ratio 0.668 (3)/0.332 (3)].Each Na(+) cation is coordinated by eight O atoms.The disorder of Na in the tunnel might presage ionic mobility for this material.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratoire de Chimie du Solide Appliquée, Faculté des Sciences, Université Mohammed V, Avenue Ibn Battouta, BP 1014, Rabat, Morocco.

ABSTRACT
The new title compound, disodium dizinc iron(III) tris-(phosphate), Na1.67Zn1.67Fe1.33(PO4)3, which belongs to the alluaudite family, has been synthesized by solid-state reactions. In this structure, all atoms are in general positions except for four, which are located on special positions of the C2/c space group. This structure is characterized by cation substitutional disorder at two sites, one situated on the special position 4e (2) and the other on the general position 8f. The 4e site is partially occupied by Na(+) [0.332 (3)], whereas the 8f site is entirely filled by a mixture of Fe and Zn. The full-occupancy sodium and zinc atoms are located at the Wyckoff positions on the inversion center 4a (-1) and on the twofold rotation axis 4e, respectively. Refinement of the occupancy ratios, bond-valence analysis and the electrical neutrality requirement of the structure lead to the given composition for the title compound. The three-dimensional framework of this structure consists of kinked chains of edge-sharing octa-hedra stacked parallel to [10-1]. The chains are formed by a succession of trimers based on [ZnO6] octa-hedra and the mixed-cation Fe(III)/Zn(II) [(Fe/Zn)O6] octa-hedra [Fe(III):Zn(III) ratio 0.668 (3)/0.332 (3)]. Continuous chains are held together by PO4 phosphate groups, forming polyhedral sheets perpendicular to [010]. The stacked sheets delimit two types of tunnels parallel to the c axis in which the sodium cations are located. Each Na(+) cation is coordinated by eight O atoms. The disorder of Na in the tunnel might presage ionic mobility for this material.

No MeSH data available.


Related in: MedlinePlus