Die Kristallstruktur von Ca2As2O7

The structure of Ca₂As₂O₇ (a ₀=7.05,b ₀=9.30,c ₀=4.89 Å; =101.3°; space groupC2/m-C _2h ³ ;Z=2) has been solved from 465 independent X-ray intensities collected on aWeissenberg-type diffractometer up to anR-factor of 2.4% for all intensities. The structure of Ca₂As₂O₇ represents a further Thortveitite structure type.

     

Darstellung und Kristallstruktur von Na2Mn3O7

Synthesis and Crystal-Structure of Na₂Mn₃O₇ Single crystals of Na₂Mn₃O₇ have been grown hydrothermally applying high oxygen pressure (p = 2 kbar). The new compound cystallizes triclinic; space group P1 ; a = 6.636(6) Å, b = 6.854(6) Å, c = 7.548(6) Å, α = 105.76(6)°, β = 106.86(6)°, γ = 111.60(6)°; Z = 2. The crystal structure has been solved and refined to R = 7.9% and R_w = 6.2% (diffractometer data, 1044 independent reflexions). The crystal structure consists of Mn₃O₇^2? anions with manganese coordinated octahedrally by oxygen. These layered anions are hold together by Na⁺ ions (coordination numbers 5 and 6).     

Die Kristallstruktur von Bi2O2Se

Bi₂O₂Se crystallizes in the (Na_0.25Bi_0.75)₂O₂Cl type structure (space group I4mmm–D _4h ¹⁷ ;a=3.891 Å,c=12.21₃ Å). The crystal chemical properties of the bismuth oxiselenide are discussed in connection with the other compounds having this structure type.

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Herrn Prof. Dr.F. Hecht zum 70. Geburtstag gewidmet.     

Die Kristallstruktur von SrCaCrF7

The Crystal Structure of SrCaCrF₇ By solid state reaction of the component fluorides at elevated temperature single crystals of SrCaCrF₇ were obtained (a = 792.3(2), b = 724.7(2), c = 986.1(2) pm; space group Pnma, Z = 4). The X‐ray structure determination confirmed isotypism with the Ca₂AlF₇ type of structure: Isolated octahedra [CrF₆]^3— (mean Cr‐F: 189.7 pm) are opposed by infinitely netted planar cations [SrFCa_2/2]³⁺ which contain “independent” F atoms 3‐coordinated by alkaline earth atoms only. The Sr atoms prefer (at a level of 80%) the 8‐fold, the Ca atoms the 7‐fold coordinated positions between the octahedra.     

Die Kristallstruktur von VO2JO3·2H 2O

The Crystal Structure of VO₂IO₃·2 H₂O VO₂IO₃ possesses a layer structure and crystallizes in the space group P2₁/c with a = 9.848(3) Å, b = 8.l58(2) Å, c = 7.192(2) Å, β = 102.17(2)° and four formula units in the unit cell. The individual layers of the structure consist of highly distorted corner- and edgesharing IO₆, and VO₆, octahedra. Only one oxygen atom is bound terminally at the vanadium, as is shown by the vibrational spectrum, too.     

Die Kristallstruktur von Mn15Si26

Zusammenfassung Neben dem bereits bekannten Mangansilicid Mn₁₁Si₁₉ (MnSi_1,727) werden folgende neue Verbindungen des Typs Mn _n Si_2n–m nachgewiesen: Mn₂₆Si₄₅ (MnSi_1,730), Mn₁₅Si₂₆ (MnSi_1,733) und Mn₂₇Si₄₇ (MnSi_1,741). Die Kristallstruktur von Mn₁₅Si₂₆ wird mit Hilfe von Fourier-und Differenz-Fourier-Synthesen bestimmt. Die Gitterparameter für die tetragonale Elementarzelle betragena=5,525 undc=65,55 Å.

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Besides the manganese silicide Mn₁₁Si₁₉ (MnSi_1.727) already reported, the following compounds of the general formula Mn _n Si_2n–m have been observed: Mn₂₆Si₄₅ (MnSi_1.730), Mn₁₅Si₂₆ (MnSi_1.733), and Mn₂₇Si₄₇ (MnSi_1.741). The crystal structure of Mn₁₅Si₂₆ has been determined by means of Fourier-and Fourier-difference-synthesis. The lattice parameters for the tetragonal unit cell have been found to be:a=5.525 andc=65.55 Å.

     

Die Kristallstruktur von MgHg(SCN)4 · 2 H2O

Crystal Structure of MgHg(SCN)₄ · 2 H₂O The crystal structure of the monoclinic MgHg(SCN)₄ · 2 H₂O (a ? 1 335.1(6) pm, b ? 531.6(5) pm, c ? 1 867.0(14) pm, β ? 92.3(1)°, Z ? 4, space group C2/c) contains nearly tetrahedral Hg(SCN)₄ and octahedral Mg(OH₂)₂(NCS)₄ groups. These groups are joined together with Hg? SCN? Mg bridges and are forming a network of layers.     

Die Kristallstruktur von Fe12Zr2P7

Zusammenfassung Die Struktur einer ternären Phase im System Fe–Zr–P wurde mit Hilfe von Einkristallaufnahmen bestimmt und verfeinert. Die Kristallart entspricht der vonVogel undDobbener aufgefundenen Phase Fe₄ZrP₂ und hat eine Idealzusammensetzung von Fe₁₂Zr₂P₇. Die Gitterparameter der hexagonalen Kristallart sinda=9,0002 undc=3,5920 Å, die Raumgruppe ist . Die Struktur ist mit jener von Fe₂P verwandt.

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The crystal structure of a ternary phase in the system Fe–Zr–P has been determined and refined by means of singlecrystal X-ray methods. The phase, already described byVogel andDobbener as Fe₄ZrP₂, has the ideal composition Fe₁₂Zr₂P₇. The cell dimensions are found to be:a=9,0002 andc=3,5920 Å, the space group is . The crystal structure of Fe₁₂Zr₂P₇ is related to Fe₂P.

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Die Kristallstruktur von RhHg2

Zusammenfassung RhHg₂ kristallisiert tetragonal mita=4,55₁ Å,c=2,99₈ Å,c/a=0.658₈ in der Raumgruppe P 4/mmm. Die Phase ist isotyp mit -PtHg₂.

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The structure of RhHg₂ was found to be tetragonal; the unit cell ofa=4,55₁ Å,c=2,99₈ Å,c/a=0,658₈ belongs to the space group P 4/mmm. RhHg₂ is isostructural with -PtHg₂.

     

Die Kristallstruktur von TaNi2

Zusammenfassung TaNi₂ kristallisiert im MoSi₂-Typ.     

Die Kristallstruktur von LiEu3O4

The crystal structure of LiEu₃O₄ which represents a new structure type was solved by usual methods with the aid of integrated WEISSENBERG photographs (MoK_α radiation, 787 reflexions) and refined to a reliability index of 4.3%. In LiEu₃O₄ just as in the first known europium(II, III)-oxide, Eu₃O₄, a clear distinction is possible between the divalent and trivalent europium ions. The given assignment which is based on crystal chemical arguments has been verified indirectly by means of the isostructural compound LiSr₂EuO₄, the cation distribution of which was established experimentally. The structure of LiEu₃O₄ is discussed in connection with the related oxides EuO and Eu₃O₄. The geometrical relations to the latter are of special interest, as LiEu₃O₄ undergoes a topotactical transformation into Eu₃O₄ by heating it in a high vacuum. There is an astonishing close structural relationship between LiEu₃O₄ and Yb₃S₄: except for lithium all the atoms are correlated as for isostructural compounds.     

Die Kristallstruktur von PrTe2

The Crystal Structure of PrTe₂ X‐ray diffraction single‐crystal structure analysis of PrTe₂ prepared by chemical vapour transport reactions starting with praseodymium and tellurium in the presence of trace amounts of iodine also revealed superstructure reflections indicating just as for CeTe₂ a (2 × 2 × 2)‐supercell of the basic anti‐Fe₂As‐type structure instead of a (2 × 2 × 1)‐supercell as for LaTe₂. In contrast to LaTe₂ with monoclinic symmetry (space group P1c1), PrTe₂ crystallizes tetragonal in the space group P4 with the lattice parameters a = 896.80(5) pm and c = 1811.9(1) pm (Z = 16). The doubling of the c‐lattice parameter compared to LaTe₂ is observed due to different polyanionic structural motifs in the heights z ≈ 0 and z ≈ ¹/₂. These are a herringbone pattern of [Te₂] dumbbell pairs (motif A; a topology which is also found in LaTe₂), isolated square four‐membered [Te₄] rings in z ≈ 0 (motif B) and additionally rectangular four‐membered [Te₄] rings in z ≈ ¹/₂ (motif C). Though CeTe₂ and PrTe₂ are crystallizing isotypically, there are distinct differences in the interatomic distances within the polyanionic Te layers and resulting from these also a different topology of the structural motif C. The individual structural elements are causing a diffraction pattern, which is all in all to be explained by a statistical superposition of the different elements in form of microdomains.     

Die Kristallstruktur von NaBiO2

The crystal structure of NaBiO₂ NaBiO₂ crystallizes monoclinic in C with a = 7.39₄, b = 7.26₂, c = 5.88₆ Å, β = 127.7°; Z = 4. Parameters were refined by least-squares (555 hkl with |h?l| = 0 to 4; R = 10.9%). Angular groups [BiO₂] are twisted by 180°, forming chains [BiO_2/2O_2/2] along [001]. The MADELUNG part of lattice energy (MAPLE) is calculated and discussed.     

Synthese und Kristallstruktur von Calcium-Kupfer-Diarsenat CaCuAs2O7

Synthesis and Crystal Structure of the Calcium Copper Diarsenate CaCuAs₂O₇ Solid state reactions led to single crystals of CaCuAs₂O₇. X-ray investigations revealed monoclinic symmetry, space group C⁵_2h-P2₁/c, lattice constants a = 7.272(1); b = 8.946(2); c = 9.307(2) Å; β = 109.48(2)°; Z = 4. CaCuAs₂O₇ is characterized by ¹_∞[CaO₆] chains, connected by As₂O₇ double tetrahedra and elongated square CuO₅ pyramids. The hitherto unknown crystal structure shows relationships to CaCuP₂O₇ but not to CaCuV₂O₇.     

Die Verfeinerung der Kristallstruktur von Li2Ge2O5

Zusammenfassung Die Kristallstruktur von Li₂Ge₂O₅ wird durchFourier- und Differenz-Fourier-Synthesen verfeinert. Als mittlere Atomabstände werden gefunden: Ge–O=1,71 und Li–O=1,96 Å.

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The crystal structure of Li₂Ge₂O₅ has been refined byFourier and difference syntheses. The average atomic distances are found to be: Ge–O=1,71 and Li–O=1,96 Å.

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Die Kristallstruktur von LiInSe2

The Crystal Structure of LiInSe₂ The crystal structure of LiInSe₂ has been determined from single crystal data (β-NaFeO₂ type, space group Pna2₁ (No. 33), a = 718.3(2), b = 839,8(3), c = 678.1(2) pm; 375 hkl, R = 0.032; R(w) = 0.029). The mean values 253.6 pm of the bond distances Li? Se are larger than calculated, the distances In? Se (256.8 pm) are equal with the calculated values. The structure is discussed in relation to the analogous LiB^IIIC₂^VI compounds.     

Die Kristallstruktur der Verbindung Cd2Ge7O16

The crystal structure of Cd₂Ge₇O₁₆ has been determined by means of three-dimensional single-crystal data. A finalR-value of 6.3% was obtained by least squares refinement based on 230 observed reflexions. The tetragonal unit cell with the lattice parametersa=11.31 andc=4.63 Å contains two formula units Cd₂Ge₇O₁₆. The compound is built up by [GeO₄]-tetrahedra and [GeO₆]-octahedra forming a three-dimensional framework with the Cd atoms located in the cavities. The average interatomic distances are found to be: Ge–O=1.74 (tetrahedra), 1.89 (octahedra) and Cd–O=2.36 Å.

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Die Kristallstruktur von Hf2Hg

Zusammenfassung Im System Hafnium-Quecksilber wurde im Temperaturbereich zwischen 500° C und 800° C nur eine Verbindung Hf₂Hg gefunden. Für diese Verbindung wird eine tetragonale Elementarzelle mita=3,34₅ Å,c=11,49₆ Å,c/a=3,436, Raumgruppe D _4h ¹⁷ –I 4/mmm vom MoSi₂-Typ vorgeschlagen.

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Investigations in the system hafnium—mercury have shown the existence of only one intermetallic compound Hf₂Hg. The structure is supposed to be tetragonal of the MoSi₂-type,a=3.34₅ Å,c=11.49₆ Å,c/a=3.436, belonging to the space group D _4h ¹⁷ –I 4/mmm.

     

Die Kristallstruktur von Mo2FeB2

Zusammenfassung Mo₂FeB₂ wird aus den Elementen synthetisiert. Diese Phase ist mit U₃Si₂ isotyp, jedoch mit Ordnung der Mo- und Fe-Atome.