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 des kaliumtetragermanats K2[Ge4O9]

Zusammenfassung Die Kristallstruktur des Kaliumtetragermanats, K₂[Ge₄O₉], wurde mit Hilfe dreidimensionaler Röntgendaten bestimmt. K₂[Ge₄O₉] kristallisiert trigonal mit der Raumgruppe P033034c1 (Nr. 165) und den Gitterparametern:a=11.84 undc=9.80 Å. Die vorgeschlagene strukturchemische Beziehung zum Wadeit, K₂Zr[Si₃O₉], wird durch die Existenz tetraedrischer [Ge₃O₉]-Ringe, die über [GeO₆]-Oktaeder zu einem dreidimensionalen Gerüst verknüpft sind, bestätigt. Es wurden folgende mittlere Ge–O-Abstände gefunden: 1.762 (Tetraeder) und 1.886 Å (Oktaeder).

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The crystal structure of potassium tetragermanate K₂[Ge₄O₉]

The crystal structure of potassium tetragermanate K₂[Ge₄O₉] has been determined by means of three-dimensional x-ray data. K₂[Ge₄O₉] crystallizes trigonal with space group P033034c1 (No. 165) and lattice parametersa=11.84 andc=9.80 Å. The proposed structural relationship to wadeite K₂Zr[Si₃O₉] is confirmed by the existence of [Ge₃O₉] rings built by tetrahedra, which are linked by [GeO₆] octahedra forming a three-dimensional network. The mean Ge–O distances are found to be: 1.762 (tetrahedra) and 1.886 Å (octahedra).

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Herrn Prof. Dr.H. Nowotny in Verehrung gewidmet.     

Die Kristallstruktur der Verbindung LiNa[Ge4O9]

Zusammenfassung Die Kristallstruktur der Verbindung LiNa[Ge₄O₉] wird durch dreidimensionale Patterson- und Fourier-Synthesen bestimmt und mit Hilfe der Methode der kleinsten Quadrate verfeinert. Die rhombische Elementarzelle (Pcca-D _2h ⁸ ) mit den Abmessungen:a=9,31,b=4,68,c=15,88 Å enthält 4 Formeleinheiten. Die Struktur wird aus [GeO₃] _n -Ketten mit tetraedrisch koordiniertem Germanium aufgebaut, die über [GeO₆]-Oktaeder zu einem dreidimensionalen Gerüst vernetzt sind. Als mittlere interatomare Ge-O-Abstände wurden erhalten: 1,758 [4] und 1,866[6] Å. Die Verbindung LiNa[Ge₄O₉] stellt ein Endglied der Mischreihe Li_2–x Na _x [Ge₄O₉] dar.

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Crystal structure of LiNa[Ge₄O₉]

The crystal structure of LiNa[Ge₄O₉] has been determined by means of three-dimensional Patterson and electron density syntheses and refined by least-squares methods. The orthorhombic unit cell (Pcca-D _2h ⁸ ) having the lattice parametersa=9.31,b=4.68 andc=15.88 Å contains 4 formula units. The crystal structure consists of [GeO₃] _n -chains of tetrahedrally coordinated Ge-atoms which are connected by [GeO₆]-octahedra to form a three-dimensional framework. The interatomic Ge-O-distances are found to be 1.758[4] and 1.866[6] Å. The compound LiNa[Ge₄O₉] represents a member of the solid solution series Li_2–x Na _x [Ge₄O₉].

     

Die Kristallstruktur von Ge5O[PO4]6

Zusammenfassung Die Kristallstruktur der Verbindung Ge₅O[PO₄]₆ wurde auf Grund dreidimensionaler Einkristalldaten ausWeissenberg-Aufnahmen ermittelt und nach der Methode der kleinsten Quadrate verfeinert: Raumgruppe ;a=7,994±0,004 undc=24,87±0,01 Å;Z=3; 467 unabhängige Reflexe;R=0,086.Die Kristallstruktur wird aus singulären [GeO₆]-Oktaedern und [Ge₂O₇]-Doppeltetraedern aufgebaut, die über [PO₄]-Tetraeder zu einem dreidimensionalen Strukturverband vernetzt sind. Die mittleren Abstände betragen: Ge^[6]–O=1,863, Ge^[4]–O=1,704 und P–O=1,525 Å.

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The crystal structure of Ge₅O[PO₄]₆

The crystal structure of Ge₅O[PO₄]₆ has been determined and refined by least-squares, using three-dimensional x-ray data fromWeissenberg-photographs: space group ;a=7.994±0.004 andc=24.87±0.01 Å;Z=3; 467 independent reflections;R=0.086.The crystal structure consists of isolated [GeO₆] octahedra and [Ge₂O₇] double tetrahedra which are linked by [PO₄] groups forming a three-dimensional network. The average interatomic distances are: Ge^[6]–O=1.863, Ge^[4]–O=1.704 and P–O=1.525 Å.

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Structure ofA2Ge4O9-Type Sodium Tetragermanate (Na2Ge4O9) and Comparison with Other Alkali Germanate and Silicate Mixed Tetrahedral–Octahedral Framework Structures

Long-standing uncertainty on the structure type of Na₂Ge₄O₉has been resolved. Sodium tetragermanate has been grown by crystallization from a supercooled melt and its single-crystal X-ray structure has been determined (R=0.022). Sodium tetragermanate is trigonal witha=11.3234(12),c=9.6817(9) Å, space groupP c1,Z=6, andD_x=4.451 g cm⁻³. The structure is comprised of a mixed tetrahedral–octahedral framework with three-membered [Ge₃O₉] rings of GeO₄tetrahedra interconnected by isolated GeO₆octahedra via shared corners and isA₂Ge₄O₉-type. Bond distances and angles for GeO₄tetrahedra and GeO₆octahedra are very similar to the corresponding values in the type structure of K₂Ge₄O₉, the two structures differing mainly in the accommodation of the smaller (medium–large-sized) Na cation, which is now in a 5+2 coordination. The structure–composition relationships of wadeite-type,A₂Ge₄O₉-type, and Na₂Si₄O₉-type structures of germanates and silicates depend largely on theT–O distance and the size of the monovalent cation. We confirm that sodium tetragermanate is a metastable phase at all pressures up to 2 kbar, the stable assemblage for the Na₂Ge₄O₉composition being sodium enneagermanate (Na₄Ge₉O₂₀) plus a more sodic phase.     

Die Kristallstruktur des Natriumorthogermanats,Na4GeO4

The crystal structure of the title compound has been determined from single crystal X-ray diffraction data and refined toR=0.125. The unit cell is triclinic, space group P, (No. 2),a=5.688(1),b=5.701(1),c=8.583(1) Å, =81.32(1), =71.50(1), =67.95(1)° andZ=2. The structure consists of isolated [GeO₄] tetrahedra linked together by four- and five-coordinate sodium atoms. Na₄GeO₄ is isostructural with Na₄CoO₄ (which has been described to be non-centrosymmetric and for which a centrosymmetric model is presented), K₄GeO₄, K₄SnO₄ and K₄PbO₄.

     

Crystal chemistry and synthesis of Ternary Silicates and Germanates containing alkali (Na+, K+) and alkaline earth (Ca2+, Sr2+, Ba2+) cations

The synthesis of new ternary silicate and germanate phases containing large alkali and alkaline-earth cations is described. They are made by solid-state reaction of mixtures of carbonates or oxalates with SiO₂ or GeO₂, or by fusion and subsequent recrystallization of the glass. Representatives of the cubic MM²⁺X₃O₉ family include Na₄CaSi₃O₉ and the isostructural compounds K₄CaGe₃O₉, K₄SrGe₃O₉ and K₄SrSi₃O₉. K₄BaSi₃O₉ is pseudocubic: the symmetry of Na₄SrSi₃O₉ is unknown. The rhombohedral MM²⁺X₁₀O₂₅ family includes K₈CaSi₁₀O₂₅, K₈SrSi₁₀O₂₅ and K₈BaSi₁₀O₂₅. Na₂CaGe₂O₆ and Na₂SrGe₂O₆ are isostructural but both are structurally unrelated to Na₂BaSi₂O₆. Na₂Ba₂Ge₂O₇ and Na₂Ba₂Si₂O₇ are structurally similar.     

The Sodium Antimony Telluridogermanate(III) Na9Sb[Ge2Te6]2

Systematic studies in the quaternary system Na/Ge/Sb/Te yielded the new compound Na₉Sb[Ge₂Te₆]₂. Its crystal structure is isotypic to Na₉Sb[Ge₂Se₆]₂ (space group C2/c with a = 9.541(2), b = 26.253(7), c = 7.5820(18) Å and β = 122.233(15)°, Z = 2). The structure is characterized by Ge–Ge dumbbells that are octahedrally coordinated by Te, forming ethane‐like [Ge₂Te₆]^6– anions. Cation sites are occupied by Na⁺ as well as shared by Na⁺ and Sb³⁺. Na₉Sb[Ge₂Te₆]₂ is formally obtained from the reaction of one equivalent Na₈[Ge₄Te₁₀] and one equivalent NaSbTe₂. In contrast to members of the metastable solid solution series (NaSbTe₂)_1–x(GeTe)_x, Na₉Sb[Ge₂Te₆]₂ is a thermodynamically stable compound. It is a semiconductor with a bandgap of 1.51 eV.     

Die Kristallstruktur des Lithiumheptagermanats Li2[Ge7O15]

Zusammenfassung Die Kristallstruktur der Verbindung Li₂[Ge₇O₁₅] wird mit Hilfe dreidimensionaler Patterson- und Fourier-Synthesen bestimmt und nach der Methode der kleinsten Quadrate verfeinert. Die Gitterparameter der orthorhombischen Elementarzelle (Pbcn — D _2h ¹⁴ ) betragen:a=7,36,b=16,76 undc=9,69 Å. Die Struktur enthält stark gewellte Schichten aus [GeO₄]-Tetraedern, die über [GeO₆]-Oktaeder zu einem dreidimensionalen Gerüst verknüpft sind; sie läßt sich durch die Formel Li₂[Ge(Ge₂O₅)₃] charakterisieren. Als mittlere Ge–O-Abstände werden erhalten: 1,735 Å (K.Z. 4) und 1,893 Å (K.Z. 6).

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The crystal structure of Li₂[Ge₇O₁₅]

The crystal structure of Li₂[Ge₇O₁₅] has been determined by means of three-dimensional Patterson and electron density syntheses, and refined by least-squares method. The lattice parameters of the orthorhombic unit cell (Pbcn-D _2h ¹⁴ ) are:a=7.36,b=16.76 andc=9.69 Å. The crystal structure contains strongly puckered layers of [GeO₄]-tetrahedra linked by [GeO₆]-octahedra to form a three-dimensional framework; the structure can be characterized by the formula Li₂[Ge(Ge₂O₅)₃]. The averaged Ge–O-distances are found to be: 1.735 Å (c. n. 4) and 1.893 Å (c.n. 6).

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Untersuchungen in den Systemen GeO2−Na2O, −K2O und −Rb2O

Zusammenfassung Die Systeme GeO₂–Na₂O, –K₂O und –Rb₂O werden röntgenographisch und differentialthermoanalytisch untersucht. Die früher beschriebene Verbindung Na₂Ge₄O₉ (I) erweist sich als identisch mit dem vonJ. F. White und Mitarbeitern angegebenen Na₄Ge₉O₂₀. Von der dargestellten isotypen Kalium-Verbindung werden die Gitterkonstanten ermittelt. Im analogen Rubidium-System läßt sich ein isotypes Enneagermanat bisher nicht nachweisen. Einkristallaufnahmen von Natriumtetragermanat [Na₂Ge₄O₉ (II)] ergeben eine hexagonale Elementarzelle mit 6 Formeleinheiten Na₂Ge₄O₉. Ebenso werden von den isotypen Kalium-und Rubidiumtetragermanaten die Gitterparameter bestimmt. Im Natrium-System stellt offensichtlich das Enneagermanat die stabile Phase dar, während das Tetragermanat nur durch rasches Abkühlen aus der Schmelze erhalten wird. Bei den Kaliumgermanaten ist dagegen das Tetragermanat die stabile Phase.Mit 2 Abbildungen     

Cluster self-organization of germanate systems: Suprapolyhedral precursor clusters and self-assembly of K2Nd4Ge4O13(OH)4, K2YbGe4O10(OH), K2Sc2Ge2O7(OH)2, and KScGe2O6(PYR)

Geometric and topological analysis of all known types of K,TR germanates (TR = La-Lu, Y, Sc, In) is carried out with the use of computer techniques (the TOPOS 4.0 program package). Framework structures are represented as three-dimensional (3D) K,TR,Ge networks (graphs) with oxygen atoms removed. The following crystal-forming 2D TR,Ge networks are determined: for K₂Nd₄Ge₄O₁₃(OH)₄, this is TR 4 3 3 4 3 3 + T 4 3 4 3; for K₂YbGe₄O₁₀(OH), this is TR 6 6 3 6 + T 1 6 8 6 + T 2 3 6 8; for K₂Sc₂Ge₂O₇(OH)₂, this is TR 6 4 6 4 + T 6 4 6; and for KScGe₂O₆, TR 6 6 3 6 3 4 + T 1 6 3 6 + T 2 6 4 3. The full 3D reconstruction of the self-assembly mechanism of crystal structures is performed as follows: precursor cluster—primary chain—microlayer-microframework (supraprecursor). In K₂Nd₄Ge₄O₁₃(OH)₄, K₂Sc₂Ge₂O₇(OH)₂, and KScGe₂O₆, an invariant type of cyclic six-polyhedral precursor cluster is identified; this precursor clusters is built of TR octahedra, which are stabilized by atoms K. For K₂Nd₄Ge₄O₁₃(OH)₄, the type of cyclic four-polyhedral precursor cluster of tetrahedron-linked TR octatopes is identified. The cluster coordination number in a layer is six (the maximum possible value) only for anhydrous germanate KScGe₂O₆ (an analogue of pyroxene, PYR); in the other OH-containing germanates, this number is four. The mechanism of formation of Ge radicals in the form of groups Ge₂O₇ and Ge₄O₁₃, a chain GeO₃, and a tubular assembly of linked cyclic groups Ge₈O₂₀ is considered.     

Crystal Growth and Structure Refinement of K4Ge9

Deep‐red moisture and air sensitive single crystals of K₄Ge₉ were obtained by reacting GeO₂ and elemental Ge with metallic W and K at high temperature in a niobium ampoule. The crystal structure of the compound was determined by single crystal X‐ray diffraction experiments. K₄Ge₉ crystallizes in a polar space group R3c (No. 161), Z = 4 with a = 21.208(1) and c = 25.096(2) Å. The compound contains discrete Ge₉^4? Wade's nido‐clusters which are packed according to a hierarchical atom‐to‐cluster replacement of the Cr₃Si prototype and are separated by K⁺ cations. Two independent [Ge₉]^4? clusters A (at Cr positions) and B (at Si positions) are found with a ratio A:B = 3:1. The B ‐type cluster satisfactorily represents orientational disorder around the three‐fold axis.     

Na12Ge17: A Compound with the Zintl Anions [Ge4]4— and [Ge9]4— — Synthesis,Crystal Structure,and Raman Spectrum

Na₁₂Ge₁₇ is prepared from the elements at 1025 K in sealed niobium ampoules. The crystal structure reinvestigation reveals a doubling of the unit cell (space group:P2₁/c; a = 22.117(3)Å, b = 12.803(3)Å, c = 41.557(6)Å, β = 91.31(2)°, Z = 16; Pearson code: mP464), furthermore, weak superstructure reflections indicate an even larger C‐centred monoclinic cell. The characteristic structural units are the isolated cluster anions [Ge₉]^4— and [Ge₄]^4— in ratio 1:2, respectively. The crystal structure represents a hierarchical cluster replacement structure of the hexagonal Laves phase MgZn₂ in which the Mg and Zn atoms are replaced by the Ge₉ and Ge₄ units, respectively. The Raman spectrum of Na₁₂Ge₁₇ exhibits the characteristic breathing modes of the constituent cluster anions at ν = 274 cm^—1 ([Ge₉]^4—) and ν = 222 cm^—1 ([Ge₄]^4—) which may be used for identification of these clusters in solid phases and in solutions. Raman spectra further prove that Na₁₂Ge₁₇ is partial soluble both in ethylenediamine and liquid ammonia. The solution and the solid extract contain solely [Ge₉]^4—. The remaining insoluble residue is Na₄Ge₄. By heating the solvate Na₄Ge₉(NH₃)_n releases NH₃ and decomposes irreversibly at 742 K, yielding Na₁₂Ge₁₇ and Ge.     

Die Kristallstruktur des Lithium-enneagermanats Li4[Ge9O20]

The crystal structure of lithium enneagermanate, Li₄[Ge₉O₂₀], has been determined and refined by least-squares, using three-dimensional single-crystal data. The compounds crystallizes with monoclinic symmetry (a=12.43,b=8.00,c=7.49 Å, =91.0^o; C2–C₂ ³) building up a framework structure which exhibits some similarity with the structures of Li₂[Ge₄O₉] and Li₂[Ge₇O₁₅]. Out of the 18 Ge-atoms in the unit cell 14 are surrounded tetrahedrally by oxygen showing an average distance of 1.757 Å; the remaining 4 Ge-atoms are octahedrally coordinated with an average distance of 1.886 Å.

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Die Kristallstruktur des Lithium-enneagermanats Li₄[Ge₉O₂₀]

Zusammenfassung Die Kristallstruktur von Lithium-enneagermanat Li₄[Ge₉O₂₀] wird an Hand dreidimensionaler Einkristalldaten ermittelt und nach der Methode der kleinsten Quadrate verfeinert (R=0,083). Die monoklin kristallisierende Verbindung (a=12,43;b=8,00;c=7,49 Å; =91,0^o; C2–C₂ ³) besitzt eine Gerüstruktur, die einen ähnlichen Aufbau wie Li₂[Ge₄O₉] und Li₂[Ge₇O₁₅] zeigt. Von den 18 Ge-Atomen in der Elementarzelle liegen 14 in tetraedrischer Koordination mit einem mittleren Ge–O-Abstand von 1,757 Å vor; 4 Ge-Atome sind oktaedrisch umgeben, mit einem mittleren Ge–O-Abstand von 1, 1886 Å.

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Herrn Professor Dr.O. Hromatka zum 65. Geburtstag gewidmet.     

Über Glasbildung und Eigenschaften von Chalkogenidsystemen. XIII. Über die Verbindungen Na6Ge2S6 · 4 CH3OH und Na6Ge2Se6 · 4 CH3OH

Glass Formation and Properties of Chalcogenide Systems. XIII. On the Compounds Na₆Ge₂S₆ · 4 CH₃OH and Na₆Ge₂Se₆ · 4 CH₃OH The glasses Ge₂S₃ and Ge₂Se₃ are soluble in solutions of Na₂S or Na₂Se in CH₃OH forming Na₆Ge₂S₆ · 4 CH₃OH and Na₆Ge₂Se₆ · 4 CH₃OH. On heating the CH₃OH-free substances are formed. From the i.r. and Raman spectra can de seen that the structure of the ions Ge₂S, Ge₂Se, P₂S₆^4?, and of Si₂Cl₆ is of the same type. The formation of the compounds can be regarded as a chemical proof for the existence of [Ge₂S₆] and [Ge₂Se₆] units as structural groups in the glasses Ge₂S₃ and Ge₂Se₃.     

Über die Silbergermanate Ag4Ge9O20 und Ag2Ge4O9

Zusammenfassung Der Germanat-Zeolith Ag₃HGe₇O₁₆·4 H₂O wird durch Ionenaustausch aus dem isotypen Ammonium-Zeolith hergestellt. Nach Dehydratation des Ag-Zeoliths bildet sich bei 460°C das zuMe ₄Ge₉O₂₀ (Me=Na, K) isotype Ag₄Ge₉O₂₀. Durch Erhitzen auf 650°C entsteht das zuMe ₂Ge₄O₉ (Me=Na, K, Rb, Tl) isotype Ag₂Ge₄O₉. Oberhalb 760°C erfolgt unter Dissoziation die Bildung von metallischem Silber und GeO₂ (Rutilform).

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The zeolithic germanate Ag₃HGe₇O₁₆·4 H₂O has been prepared by ion-exchange from the analogous ammonium compound. After dehydration at 460°C Ag₄Ge₉O₂₀ is formed, which is isostructural withMe ₄Ge₉O₂₀ (Me=Na, K). By heating up to 650°C Ag₂Ge₄O₉ is obtained, having the structure ofMe ₂Ge₄O₉ (Me=Na, K, Rb, Tl). Above 760°C the compound decomposes into silver, oxygen and GeO₂ (rutile).

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Na6[Ti5O12(OH)2]: A New Titanate Containing $\rm{{_{\infty }^{1}}}$[Ti5O12(OH)2]6− Ribbons

Na₆[Ti₅O₁₂(OH)₂] is the first structurally characterized sodium oxohydroxotitanate. The compound can be prepared via hydrothermal treatment of TiO₂ (Anatas) in NaOH (10n ) for 96 h at 250° in an autoclave. The crystal structure of Na₆[Ti₅O₁₂(OH)₂] consists of infinite ribbons [Ti₅O₁₂(OH)₂]^6?. The orthorhombic arrangement has Pbcn (No. 60) symmetry with the lattice constants a=18.668(4) Å, b=6.5333(13) Å, and c=9.829(2) Å.     

Komplexverbindungen von Germaniumsäure mit ÄDTE und ÄDTE-Analogen, 2. Mitt.: 1,2-Diaminopropan-N,N,N′,N′-tetraessigsäure; N-2-Hydroxyäthyl-1,2-diaminoäthan-N,N′,N′-triessigsäure

Zusammenfassung Feste 11-Komplexverbindungen von Germaniumsäure mit 1,2-Diaminopropan-N,N,N,N-tetraessigsäure und N-2-Hydroxyäthyl-1,2-diaminoäthan-N,N,N-triessigsäure werden dargestellt. Auf Grund von TG-, DTG-, DTA- sowie IR-spektroskopischen Untersuchungen wird ein Strukturvorschlag für die erhaltenen Verbindungen (GeY·2 H₂O, GeY, GeZ·H₂O, GeZ, GeX·H₂O, GeX ^*** abgeleitet.In wäßriger Lösung erweist sich GeZ·H₂O als einbasige Säure, H[Ge(OH)Z], mit einer DissoziationskonstanteK _c =3,15·10^–3 (pK _c =2,50±0,03) für 25° C, Ionenstärke 0,1m.Es werden die Stabilitätskonstanten der Komplexverbindungen H[Ge(OH)Z], [Ge(OH)Z]^– und GeX·H₂O in wäßriger Lösung bestimmt: (25° C, Ionenstärke 0,1 m).Mit 3 Abbildungen1. Mitt.:N. Konopik undP. Mészáros, Mh. Chem.99, 902 (1968).Auszugsweise vorgetragen auf der Jahrestagung des Vereines Österreichischer Chemiker am 5. Oktober 1967 in Wien. Vgl. Allgem. u. Prakt. Chemie18, 268 (1967).     

IrIn7GeO8 = [IrIn6](GeO4)(InO4) und Verbindungen der Mischkristallreihe [IrIn6](Ge1+xIn1−4x/3O8) (0 ≤ x ≤ 0.75) – erste Oxide mit [IrIn6]‐Oktaedern

IrIn₇GeO₈ = [IrIn₆](GeO₄)(InO₄) and Compounds of the Solid Solution Series [IrIn₆](Ge_1+xIn_1?4x/3O₈) (0 ≤ x ≤ 0.75): First Oxides containing [IrIn₆] Octahedra The low valent indiumoxides IrIn₇GeO₈ = [IrIn₆](GeO₄)(InO₄) and [IrIn₆](Ge_1+xIn_1?4x/3O₈) (0 x ≤ 0.75) are formed by heating intimate mixtures of Ir, In, In₂O₃ and GeO₂ in corundum crucibles under an atmosphere of argon (1420 K, 70 h). The compounds are black and semiconducting. X‐ray powder diffraction patterns can be indexed on the basis of a face centered cubic unit cell with lattice parameters ranging from a = 1012.3(1) pm (x = 0) to a = 1007.3(1) pm (x = 0.75). Characteristic building units in [IrIn₆](Ge_1+xIn_1?4x/3O₈) are isolated [IrIn₆]⁹⁺ octahedra with short Ir‐In distances of 253.5 pm, which are linked via [GeO₄]^4? and [InO₄]^5? tetrahedra to a three dimensional framework. Starting from IrIn₇GeO₈ = [IrIn₆](GeO₄)(InO₄), the isoelectronic substitution of 4 In³⁺ ions by 3 Ge⁴⁺ ions and one Ge‐vacancy leads to the formation of a solid solution series [IrIn₆](GeO₄)_1+x(O₄)_x/3(InO₄)_1?4x/3, which shows a slight decrease in the cubic lattice parameter with increasing x. According to Rietveld refinements the structure of [IrIn₆](GeO₄)(InO₄) exhibits a statistical distribution of the tetrahedrally coordinated Ge and In atoms ( , R(prof.) = 4.4 %, R(int.) = 2.5 %). The crystal and electronic structures of [IrIn₆](GeO₄)(InO₄) are discussed on the basis of first principles electronic structure calculations.     

A taxonomy of apatite frameworks for the crystal chemical design of fuel cell electrolytes

Apatite framework taxonomy succinctly rationalises the crystallographic modifications of this structural family as a function of chemical composition. Taking the neutral apatite [La₈Sr₂][(GeO₄)₆]O₂ as a prototype electrolyte, this classification scheme correctly predicted that ‘excess’ oxygen in La₉SrGe₆O_26.5 is tenanted in the framework as [La₉Sr][(GeO₄)_5.5(GeO₅)_0.5]O₂, rather than the presumptive tunnel location of [La₉Sr][(GeO₄)₆]O_2.5. The implication of this approach is that in addition to the three known apatite genera—A₁₀(BO₃)₆X₂, A₁₀(BO₄)₆X₂, A₁₀(BO₅)₆X₂—hybrid electrolytes of the types A₁₀(BO₃/BO₄/BO₅)₆X₂ can be designed, with potentially superior low-temperature ion conduction, mediated by the introduction of oxygen to the framework reservoir.