| 1. |
- Nilsson, Göran, et al.
(författare)
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Crystal Structure of BaNb6.3(1)Ti3.6(1)O16 containing Nb6O12, fused Ti3O13 Clusters and Ti3O10 Units
- 2000
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Ingår i: Zeitschrift für Anorganische und Allgemeines Chemie. - 0044-2313 .- 1521-3749. ; 626:1, s. 160-172
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Tidskriftsartikel (refereegranskat)abstract
- A new phase, BaNb6.3(1)Ti3.6(1)O16, has been synthesised. Electron diffraction studies indicate an hexagonal substructure with unit cell parameters a ≈ 8.9 Å and c ≈ 9.5 Å. In some of the ED patterns superstructure reflections are present, indicating a supercell with a = √3 · asub and c = csub. However, X-ray single-crystal diffraction studies of a crystallite yielding reflections corresponding to the supercell revealed it to be monoclinic, with the unit cell parameters a = 26.811(2) Å, b = 15.4798(2) Å, c = 9.414(2) Å, β = γ = 90° and α = 90.0(3)°. The average crystal structure was refined, using the subcell with a = 8.937(2) Å, b = 15.479(2) Å, c = 9.414(2) Å, β = γ = 90° and α = 90.0(3)°, space group Cm11, and Z = 4, to RI = 3.24% and RwI = 3.44%. The structure can be described as an hexagonal close packing layers of Nb6 octahedra, Ba, and O atoms (A1, A2) and layers of O atoms (B1, B2), appearing in the packing sequence: A1B1A2B2. The Nb6 octahedra are found in isolated Nb6O12O6 clusters, and the Ti atoms in Ti3O13 and Ti3O10 units in octahedral and tetrahedral voids formed by O atoms, respectively. The Ti positions were found to be only partly occupied. Microanalysis indicates that some Nb atoms are located in the Ti3 triangles. A model is presented that interprets these not fully occupied Ti3 triangles as a result of a superimposing of three different structures. Two of these consist of two fused Ti3O13 units, forming an Ti6O19 unit, and a Ti3O10 unit, while the third consists of alternating Ti3O13 units.
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| 2. |
- Akselrud, Lev, et al.
(författare)
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Order and disorder in the modulated phase hp-Mg9Ge5.1
- 2022
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Ingår i: Zeitschrift fur Anorganische und Allgemeine Chemie. - : Wiley. - 0044-2313 .- 1521-3749. ; 648:10
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Tidskriftsartikel (refereegranskat)abstract
- Single crystals of Mg9Ge5.1(2) were obtained at a pressure of 5 GPa in the temperature range 723 to 1273 K. The metastable high-pressure phase exhibits a crystal structure, which may be described as a host-guest variety of an UCl3-type framework. The atomic arrangement is characterized by a host crystal structure Mg9Ge3 with disordered germanium guests (≈2 Ge per formula unit) in the channels. The composite arrangement undergoes incommensurate modulation. Upon heating at ambient pressure, the phase transforms into the thermodynamically stable compounds Mg2Ge and Ge at 496(5) K. Measurements of the magnetic susceptibility indicate diamagnetic behavior between 75 and 350 K.
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| 3. |
- Angus-Dunne, Sarah, et al.
(författare)
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Synthesis and Crystal Structure of the Palladium(IV) Polyoxomolybdate, K0 75Na3 75[PdMo6O24H3 5]center dot 17H(2)O
- 2010
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Ingår i: Zeitschrift für Anorganische und Allgemeines Chemie. - : Wiley. - 0044-2313 .- 1521-3749. ; 636:5, s. 727-734
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Tidskriftsartikel (refereegranskat)abstract
- The first example of a heteropolyoxomolybdate containing palladium(IV) was isolated and characterized by X ray crystallography The palladium(IV) hexamolybdate, K0 75Na3 75[PdMo6O24H3 (5)] 17H(2)O, was isolated from an aqueous solution at pH 4 5 in the space group P (1) over bar a 10 790(2) b 12 244(3), c 14 086(3) angstrom, alpha 113 77(1), beta 90 41(1) gamma 107 86(1)degrees and the structure was determined using X ray diffraction methods refining to a residual of 0 0301 for 5334 reflections A formal [PdMo6O24H3](5-) subunit exhibits the basic Anderson structure with two [PdMo6O24H3](5-) cluster anions in the structure bridged by a hydrogen atom (formally an H+) situated on a center of symmetry to give a [Pd2Mo12O48H7](9-) dimeric anion The palladium(IV) atom occupies a slightly distorted octahedral environment with Pd-O distances ranging from 1 968 to 2 009 angstrom.
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| 4. |
- Auer, Henry, et al.
(författare)
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The Hydrogenation of the Zintl Phase NdGa Studied by in situ Neutron Diffraction
- 2019
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Ingår i: Zeitschrift für Anorganische und Allgemeines Chemie. - : Wiley. - 0044-2313 .- 1521-3749. ; 645:3, s. 175-181
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Tidskriftsartikel (refereegranskat)abstract
- The hydrogenation of the Zintl phase NdGa was studied by in situ neutron powder diffraction. We find a compositional range of 0.1 < x < 0.8 in NdGaH1+x. Hydrogen atoms are located in two different positions, in HNd4 tetrahedra, and close to the polyanionic chains. For the latter, the Ga-H distance in NdGaH1.66 is quite long (ca. 200 pm) with a trigonal bipyramidal Nd3Ga2 surrounding of hydrogen atoms. Hydrogen poor NdGaH<1 phases as known for similar systems were not observed. The changing hydrogen content shows no measureable effect on the unit cell volume, but on lattice parameter ratios. Superstructures occur for 0.53 < x < 0.66 and 0.73 < x < 0.8, leading to a doubling or tripling of the lattice parameter a. They are probably caused by partial hydrogen ordering. The threefold superstructure contains a (1)[(Ga-H-Ga-H-Ga)(6-)] moiety with hydrogen bridging two gallium chains.
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| 5. |
- Becker, Richard, et al.
(författare)
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Crystal Structure of the New Cobalt Tellurite Chloride Co5Te4O11Cl4
- 2007
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Ingår i: Zeitschrift für Anorganische und Allgemeines Chemie. - Weinheim : WILEY-VCH Verlag. - 0044-2313 .- 1521-3749. ; 633:3, s. 422-424
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Tidskriftsartikel (refereegranskat)abstract
- The crystal structure of the new compound Co5Te4O11Cl4 is described. It crystallizes in the triclinic system, space group P-1 with the unit cell parameters a = 822.26(8) pm, b = 1029.7(1) pm, c = 1031.1(1) pm, = 110.80(1)°, β = 97.950(9)°, = 98.260(9)° and Z = 2. The structure is layered along the bc–plane and built by [CoO5Cl], [CoO4Cl2] and [CoO4Cl] polyhedra sandwiched by [TeO3E] and [TeO4E] polyhedra. The layers can be regarded as infinite molecules without any net charge and only weak van der Waals forces connect them to each other. The halides and the lone-pair, E, of TeIV protrude from the layers.
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| 6. |
- Casari, Barbara M., et al.
(författare)
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New Aquapentachlorochromate(III) Compounds: K2[CrCl5(H2O)] and (NH4)2[CrCl5(H2O)]
- 2006
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Ingår i: Zeitschrift für Anorganische und Allgemeine Chemie. - 0044-2313 .- 1521-3749. ; 632:1, s. 101-106
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Tidskriftsartikel (refereegranskat)abstract
- Synthesis and crystal structures of two new compounds, K2[CrCl5(H2O)] (I) and (NH4)2[CrCl5(H2O)] (II) are reported. Both compounds were prepared from chromium(VI) salts by two different methods and reaction pathways of these syntheses are suggested. The crystal structures of these two aquapentachlorochromates(III) have been determined from three dimensional X-ray data collected at low temperature, 173 K. The two structures are isomorphous and their unit cell dimensions are quite similar. They are orthorhombic, space groups Pnma, with Z = 4. Both structures are composed of [CrCl5(H2O)]2- units held together by the counterion framework. The coordination around the chromium ion deviates from a regular octahedron due to the shorter equatorial chromium-oxygen bond.
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| 7. |
- Casari, Barbara M., et al.
(författare)
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New Structure Type among Octahydrated Rare-Earth Sulfates, β-Ce2(SO4)3·8H2O, and a new Ce2(SO4)3·4H2O Polymorph
- 2007
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Ingår i: Zeitschrift für Anorganische und Allgemeine Chemie. - : Wiley. - 0044-2313 .- 1521-3749. ; 633:7, s. 1074-1081
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Tidskriftsartikel (refereegranskat)abstract
- Syntheses, crystal structures and thermal behavior of two new hydrated cerium(III) sulfates are reported, Ce2(SO4)3·4H2O (I) and β-Ce2(SO4)3·8H2O (II), both forming three-dimensional networks. Compound I crystallizes in the space group P21/n. There are two non-equivalent cerium atoms in the structure of I, one nine- and one ten-fold coordinated to oxygen atoms. The cerium polyhedra are edge sharing, forming helically propagating chains, held together by sulfate groups. The structure is compact, all the sulfate groups are edge-sharing with cerium polyhedra and one third of the oxygen atoms, belonging to sulfate groups, are in the S-Oμ3-Ce2 bonding mode. Compound II constitutes a new structure type among the octahydrated rare-earth sulfates which belongs to the space group Pn. Each cerium atom is in contact with nine oxygen atoms, these belong to four water molecules, three corner sharing and one edge sharing sulfate groups. The crystal structure is built up by layers of [Ce(H2O)4(SO4)]nn+ held together by doubly edge sharing sulfate groups. The dehydration of II is a three step process, forming Ce2(SO4)3·5H2O, Ce2(SO4)3·4H2O and Ce2(SO4)3, respectively. During the oxidative decomposition of the anhydrous form, Ce2(SO4)3, into the final product CeO2, small amount of CeO(SO4) as an intermediate species was detected.
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| 8. |
- Casari, Barbara M., et al.
(författare)
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Syntheses and Crystal Structures of Hydrated Ternary Cerium Sulfates: Mixed-valence K5Ce2(SO4)6·H2O and K2Ce(SO4)3·H2O
- 2007
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Ingår i: Zeitschrift für Anorganische und Allgemeine Chemie. - : Wiley. - 0044-2313 .- 1521-3749. ; 633:7, s. 1055-1061
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Tidskriftsartikel (refereegranskat)abstract
- A new chemical and structural interpretation of K5Ce2(SO4)6·H2O (I) and a redetermination of the structure of K2Ce(SO4)3·H2O (II) is presented. The mixed-valent compound I crystallizes in the space group C2/c with a = 17.7321(3), b = 7.0599(1), c = 19.4628(4) Å, beta = 112.373(1)° and Z = 4. Compound I has been discussed earlier with space group Cc. In the structure of I, there are pairs of edge sharing cerium polyhedra connected by sulfate oxygen atoms in the 3 bonding mode. These cerium dimers are linked through edge and corner sharing sulfate bridges, forming layers. The layers are joined by potassium ions which together with the water molecules are placed between the layers. No irregularity in the distribution of the CeIII and CeIV to cause the lost of a crystallographic center of symmetry was detected. We suggest that the charge exerted by the extra f1 electron for every cerium dimer is delocalized over the Ce1-O2-Ce2 moiety in a non-bonding mode. As a result, the oxidations state of each cerium ion is a mean value between III and IV at each atomic position. Compound II crystallizes in the space group C2 with a = 20.6149(2), b = 7.0742(1), c = 17.8570(1) Å, beta = 122.720(1)° and Z = 8. The hydrogen atoms have been located and the absolute structure has been established. Neither hydrogen atom positions nor anisotropic displacement parameters were given in the previous reports. In compound II, the cerium polyhedra are connected by edge and corner sharing sulfate groups forming a three-dimensional network. This network contains Z-shaped channels hosting the charge compensating potassium ions.
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| 9. |
- Eklöf, Daniel, et al.
(författare)
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Transport Properties of Ag-doped ZnSb
- 2021
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Ingår i: Zeitschrift für Anorganische und Allgemeines Chemie. - : Wiley. - 0044-2313 .- 1521-3749. ; 647:2-3, s. 34-40
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Tidskriftsartikel (refereegranskat)abstract
- The intermetallic compound ZnSb is a (II-V) narrow gap semiconductor with interesting thermoelectric properties. Electrical resistivity, Hall coefficient, thermopower and thermal conductivity were measured up to 400 K on Ag-doped samples with concentrations 0.2, 0.5, 1, 2, and 3 at.%, which were consolidated to densities in excess of 99.5 % by spark plasma sintering. The work confirms a huge improvement of the thermoelectric Figure-of-merit, ZT, upon Ag doping. The optimum doping level is near 0.5 at.% Ag and results in ZT values around 1.05 at 390 K. The improvement stems from a largely decreased resistivity, which in turn relates to an increase of the hole charge carrier concentration by two orders of magnitude. It is argued that Ag can replace minute concentrations of Zn (on the order of 0.2 at.%) in the crystal structure which enhances the intrinsic impurity band of ZnSb. Excess Ag was found to segregate in grain boundaries. So the best performing material may be considered as a composite Zn similar to 0.998Ag similar to 0.002Sb/Ag-similar to 0.003.
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| 10. |
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