Kristallstruktur und Fehlordnung des Artinits Mg2[CO3(OH)2]·3 H2O

Zusammenfassung Röntgenbeugungsaufnahmen des Artinits zeigen diffuse Schichtlinien für k=ungerade. Die vorläufige Strukturbestimmung vonde Wolff, die nur die scharfen Reflexe berücksichtigt, wurde verfeinert. Die Struktur besteht danach aus Mg(OH)₃(H₂O)₂O-Oktaedern, die über Kanten zu Ketten mit angehängten Karbonatgruppen verknüpft sind. H₂O und CO₃ alternieren statistisch in der Kette. Die elektrisch neutralen Ketten sind durch Wasserstoffbrückenbindung zwischen den Karbonatgruppen und Kristallwasser verbunden.Die Fehlordnung kann als eine Lagenstatistik der Karbonatgruppen und eines der drei Kristallwasser beschrieben werden, die geordnete Ketten mit doppelter Identitätsperiode und einer zufälligen Lage bilden. Die Theorie der Röntgenbeugung an solchen Anordnungen wird allgemein diskutiert, und die Gleichungen, die das Verhalten der diffusen Schichtlinie beschreiben, werden abgeleitet. Nach den vorliegenden Untersuchungen gibt es zwei Ordnungsvorgänge mit versehiedenen Wechselwirkungsenergien. Der eine Prozeß führt zu geordneten Schichten, deren gegenseitige Lage rein zufällig ist, der andere, schwerer zu übersehende Ordnungsvorgang ist durch Wechselwirkungen großer Reichweite bestimmt und weicht bemerkenswert von den Bauprinzipien der geordneten Schicht ab.

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Summary X-ray diffraction photographs of Artinite exhibit weak diffuse layer-lines for k=odd. The preliminary structure determination byde Wolff, considering the sharp reflection only, has been refined. The structure consists of Mg(OH)₃(H₂O)₂O-octahedra, linked over edges to chains with attached CO₃-groups, which alternate statistically with H₂O. The electrically neutral chains are linked by hydrogen bonds between the water molecules and the CO₃-groups.The disorder phenomenon can be described as statistics of positions of the Carbonate groups and one of the 3 water molecules, which form strictly ordered chains with a doubled identy period and a random position. The theory of X-ray diffraction of such arrangements is generally discussed and some formulae for the diffuse layers in reciprocal space are given. Two ordering processes are found experimentally, which cannot be explained in terms of similar interactions. One of these ordering principles leads to ordered layers arranged at random with respect to their mutual positions. Long range interactions determine the second, more complex ordering process, which shows some remarkable deviations from the disordered layer structure.

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Herrn Professor Dr.F. Machatschki zum 70. Geburtstag gewidmet.     

The charge density distribution and antiferromagnetic properties of azurite Cu3[CO3]2(OH)2

 The structure and bonding in azurite are investigated on the basis of accurate single-crystal X-ray diffraction data. Both spherical IAM and pseudoatom models have been used in the refinements. The deformation electron density: dynamic (IAM) and static (pseudoatom) are mapped for the CO₃ group and for Cu(1) and Cu(2) squares in different sections. The carbonate group in azurite, not constrained to have trigonal symmetry, exhibits peaks in both static and dynamic maps which result from σ-bonds between C–sp² hybrid orbitals and O–p orbitals with some delocalisation of density in the dynamic map because of the thermal motion of oxygens. For the analysis of crystal fields and for the multipole calculations, coordinate systems on the Cu-atoms have been chosen as for a Jahn-Teller octahedron, but with the normal to the square as the z-axis instead of the absent apical oxygens. In both Cu squares there are peaks which result from single Cu–O σ-bonds. Most remarkable is the preferential occupation of the non-bonding 3d orbitals of Cu-atoms being above and below the Cu-squares. The centre of these peaks for the Cu(1)-atom makes an angle with the c-axis ∼53° in the ac plane. This direction corresponds to the maximum magnetic susceptibility at ambient temperature. The real atomic charges of Cu-atoms in azurite determined from multipoles are close to Cu⁺¹. The occupancies of the 3d atomic orbitals show that non-bonding orbitals in both Cu-atoms are most populated, in contrast to bonding orbitals, as is typical for the Jahn-Teller octahedron. The absence of apical oxygens makes this effect even more pronounced. It is suggested that the antiferromagnetic structure below 1.4 K will be collinear and commensurate with b′=2b. Received: 8 September 2000 / Accepted: 6 March 2001     

Die Kristallstruktur von Poughit,Fe2[TeO3]2[SO4]·3H2O

Zusammenfassung Poughit, Fe₂[TeO₃]₂[SO₄]·3H₂O, kristallisiert in der Raumgruppe C_2v ⁹=P 2₁nb;a ₀=9,66 Å,b ₀=14,20 Å,c ₀=7,86 Å; Z=4. Die Kristall-struktur wurde aus photographischen Röntgendaten mit Hilfe dreidimensionaler Patterson- und Fourier-Funktionen ermittelt. In der Atomanordnung ist das Eisen verzerrt oktaedrisch von sechs Sauerstoffen umgeben. Die Telluratome bilden mit drei Sauerstoffen trigonale Pyramiden, welche die Eisenoktaeder in zwei Dimensionen verknüpfen.

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The crystal structure of Poughite, Fe₂[TeO₃]₂[SO₄]·3H₂O

Summary Poughite, Fe₂[TeO₃]₂[SO₄]·3H₂O, crystallizes in space group C_2v ⁹=P 2₁nb;a ₀=9.66 Å,b ₀=14.20 Å,c ₀=7.86 Å; Z=4. The crystal structure is derived from photographic X-ray data by means of 3-dimensional Patterson-and Fourier-functions. In the atomic arrangement the iron has a distorted octahedral coordination. The Te-atoms form with three oxygens trigonal pyramids which connect the iron-octahedra to 2-dimensional sheets.

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Synthetic bayleyite,Mg2[UO2(CO3)3]·18H2O: Thermochemistry,crystallography and crystal structure

Summary Thermochemistry, morphology, optical properties and crystal structure of synthetic bayleyite, Mg₂[UO₂(CO₃)₃]·18H₂O, monoclinic, have been studied. Incongruent melting at 55°, three steps of dehydration and two steps of decarboxylation have been found by thermochemic investigations. Morphology: Prisms along [001] with {100}, {110}, {210}, {001}, {401}, {021}, {211}, {111} and as the most important forms. Optical data:n =1.453,n =1.498,n =1.499, 2V _x =16°,Y=b,X c=11°. Crystal structure: Space groupP2₁/a,a=26.560(3),b=15.256(2),c=6.505(1) Å, =92.90(1)°,Z=4,R=0.029 for 5126 independent reflections measured with MoK -radiation. The structure is built up from isolated Mg(H₂O)₆ octahedra, UO₂(CO₃)₃ units and lattice water molecules, all held together by hydrogen bonds only.

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Synthetischer Bayleyit, Mg₂[UO₂(CO₃)₃]·18H₂O: Thermochemie, Kristallographie und Kristallstruktur

Zuseammenfasung Thermochemie, Morphologie, optische Eigenschaften und Kristallstruktur von Bayleyit, Mg₂[UO₂(CO₃)₃]·18H₂O, monoklin, wurden anhand künstlich hergestellter Kristalle untersucht. Durch thermochemische Untersuchung wurden inkongruentes Schmelzen bei 55°, eine dreistufige Wasserabgabe sowie eine zweistufige CO₂-Abgabe festgestellt. Morphologie: parallel zu [001] gestreckte Prismen mit {100}, {110}, {210}, {001}, {401}, {021}, {211}, {111}, und {311} als wichtigste Formen. Optische Daten:n =1.453,n =1.498,n =1.499, 2V _x =16°,Y=b,X c=11°. Kristallstruktur: RaumgruppeP2₁/a,a=26.560(3),b=15.256(2),c=6.505(1) Å, =92.90(1)°,Z=4;R=0.029 für 5126 unabhängige, mit MoK -Strahlung gemessene Reflexe. Die Struktur enthält isolierte Mg(H₂O)₆-Oktaeder, UO₂(CO₃)₃-Gruppen und freie Wassermoleküle, die ausschließlich durch Wasserstoffbrücken miteinander verknüpft sind.

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With 4 Figures     

Stable Isotope Fractionation during Experimental Formation of Norsethite (BaMg[CO3]2): A Mineral Analogue of Dolomite

Stable oxygen and carbon isotopefractionation during the experimental formation ofordered norsethite (BaMg[CO₃]₂) from thereaction of anhydrous BaCO₃ (witherite) withrelatively low concentrated sodium-magnesiumbicarbonate solutions has been studied between20° and 135 °C. In the investigatedtemperature range, ¹⁸O and ¹³C are enrichedin norsethite with respect to water and gaseous carbondioxide, respectively. Whereas ¹⁸O/¹⁶Opartitioning is intermediate between those of theBaCO₃–H₂O and MgCO₃–H₂O systems,¹³C/¹²C partitioning is more similar to thatfor BaCO₃–CO₂. Between 20° and90°C, the temperature dependences of the¹⁸O/¹⁶O and ¹³C/¹²C fractionationfactors are represented by the equations (T in °K):10³ ln _BaMg[CO₃]₂-H_2O = 2.83 10⁶T^--2.85, and 10³ln_BaMg[CO₃]₂-CO₂(gas) = 1.78 10⁶T^--10.16. The later equation considers carbon isotope fractionationbetween the dissolved carbonate ion and carbon dioxide measured by Halaset al. (1997). Under standard state conditions (25 °C) the fractionation factors in the system BaMg[CO₃]₂-CO₂-H₂O are: Oxygen isotopes: _BaMg(CO₃)₂-H_2O = 1.02941, _BaMg(CO₃)₂-OH-(aq) = 1.07059,_BaMg(CO₃)₂-CO₂(gas) = 0.98868, and_BaMg(CO₃)₂-H₂CO₃ ^* = 0.98843; carbon isotopes:_BaMg(CO₃)₂-CO₂(gas) = 1.00992,_BaMg(CO₃)₂-H₂CO₃ ^* = 1.01099,_BaMg(CO₃)₂-HCO₃ ^- = 1.00194,_BaMg(CO₃)₂-CO₃ ^2- = 1.00491 or 1.00150.The spontaneous precipitation of aBaMg[CO₃]₂ gel at 20 °C,followed by the alteration of the products at20° or 60°C for 31 days,demonstrated isotope exchange reactions betweensolids and mother solutions dueto recrystallization. Isotope equilibrium, wasnot reached within run time.     

Die Kristallstruktur des Ferrinatrits,Na3Fe[SO4]3 · 3H2O

Zusammenfassung Die Kristallstruktur des Ferrinatrits, Na₃Fe[SO₄]₃·3H₂O, Raumgruppe ,a _o=15,560 Å,c _o=8,666 Å,Z=6, wurde mittels der mit einem Zweikreis-Diffrak tometer gemessenen Röntgen-Intensitäten bestimmt und für 1591 symmetrieunabhängigeF _obs aufR=0,047 verfeinert. In Ferrinatrit sind FeO₆-Oktaeder und Sulfattetraeder über gemeinsame Ecken zu Ketten verknüpft. Diese Ketten verlaufen parallelz und sind untereinander über Natriumionen und Wassermoleküle verbunden. Die Mittelwerte der wichtigsten Bindun gslängen betrgen: Fe–O=1,997 Å, S–O=1,474 Å, Na–(4×O+2×Ow)=2,49 Å.

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The crystal structure of ferrinatrite, Na₃Fe[SO₄]₃ · 3H₂O

Summary The crystal structure of ferrinatrite, Na₃Fe[SO₄]₃·3H₂O, space group ,a ₀=15.560 Å,c ₀=8.666 Å,Z=6, was determined from X-ray intensities measured on a 2-circle diffractometer and was refined using 1591 independentF _obs toR=0.047. FeO₆ Octahedra and sulfate tetrahedra share common corners to from infinite chains which run parallel toz and are linked by sodium ions and water molecules. Important average bond lengths are: Fe–O=1.997 Å, S–O=1.474Å, Na-(4×0+2×Ow)=2.49 Å.

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Herrn Prof. DDr.H. Wieseneder zum 70. Geburtstag gewidmet.     

On the system Ba [Al2Si2O8]-Ca[Al2Si2O8]

First results obtained in the study of the Ca-Ba diadochic substitution in the several polymorphic modifications of BaAl₂Si₂O₈ are reported:

1. in the hexagonal modifications synthesized at 1200° C by a solid state reaction, Ca replaces Ba up to 37% (atomic fraction);
2. in the hexagonal modifications obtained by crystallization of a melt, the replacement is limited to 25%;
3. in the monoclinic modifications obtained by heating the above mentioned modifications to 1450° C, the replacement is limited to 25% again.

A remarkable feature of the low and high hexagonal modifications is that their unit-cell parameters show no variation with composition. These hexagonal phases, furthermore, seem identical irrespective of the method of synthesis. The unit-cell parameters of the monoclinic phases vary very little with composition.     

High pressure single-crystal synthesis, structure and compressibility of the garnet Mn2+ 3Mn3+ 2[SiO4]3

Single crystals of the garnet Mn²⁺ ₃Mn³⁺ ₂[SiO₄]₃ and coesite were synthesised from MnO₂-SiO₂ oxide mixtures at 1000°C and 9 GPa in a multianvil press. The crystal structure of the garnet [space group Ia3¯d, a=11.801(2) Å] was refined at room temperature and 100 K from single-crystal X-ray data to R1=2.36% and R1=2.71%, respectively. In contrast to tetragonal Ca₃Mn³⁺ ₂[GeO₄]₃ (space group I4₁/a), the high-pressure garnet is cubic and does not display an ordered Jahn-Teller distortion of octahedral Mn³⁺. A disordered Jahn-Teller distortion either dynamic or static is evidenced by unusual high anisotropic displacement parameters. The room temperature structure is characterised by following bond lengths: Si-O=1.636(4) Å (tetrahedron), Mn³⁺-O=1.995 (4) Å (octahedron), Mn²⁺-O=2.280(5) and 2.409(4) Å (dodecahedron). The cubic structure was preserved upon cooling to 100 K [a=11.788(2) Å] and upon compressing up to 11.8 GPa in a diamond-anvil cell. Pressure variation of the unit cell parameter expressed by a third-order Birch-Murnaghan equation of state led to a bulk modulus K ₀=151.6(8) GPa and its pressure derivatives K′=6.38(19). The peak positions of the Raman spectrum recorded for Mn²⁺ ₃Mn³⁺ ₂[SiO₄]₃ were assigned based on a calderite Mn²⁺ ₃Fe³⁺ ₂[SiO₄]₃ model extrapolated from andradite and grossular literature data.     

G2 theory calculations on [H3SiO4]−, [H4]SiO4], [H3AlO4]2−, [H4AlO4]− and [H5AlO4]: Basis set and electron correlation effects on molecular structures,atomic charges,infrared spectra,and potential energies

G2 theory calculations were performed on [H₃SiO₄]^?, H₄SiO₄, [H₃AlO₄]^2?, [H₄AlO₄]^?, and [H₅AlO₄]. Molecular structures, atomic charges, and infrared spectra at the HF/6-31G^* and MP2/6-31G^* levels are compared. The influence of polarization and diffuse functions on the structure of [H₃SiO₄]^? is also examined. Basis set and electron correlation effects on potential energies are assessed by comparing various levels of theory. Proton affinities of these gas-phase molecules and related mineral surface species are predicted based on corrections for cluster-size effects.     

Ab initio quantum-mechanical modeling of pyrophyllite [Al2Si4O10(OH)2] and talc [Mg3Si4O10(OH)2] surfaces

Bulk and slab geometry optimizations and calculations of the electrostatic potential at the surface of both pyrophyllite [Al₂Si₄O₁₀(OH)₂] and talc [Mg₃Si₄O₁₀(OH)₂] were performed at Hartree–Fock and DFT level. In both pyrophyllite and talc cases, a modest (001) surface relaxation was observed, and the surface preserves the structural features of the crystal: in the case of pyrophyllite the tetrahedral and octahedral sheets are strongly distorted with respect to the ideal hexagonal symmetry (and basal oxygen are located at different heights along the direction normal to the basal plane), whereas the structure of talc deviates slightly from the ideal hexagonal symmetry (almost co-planar basal oxygen). The calculated distortions are fully consistent with those experimentally observed. Although the potentials at the surface of pyrophyllite and talc are of the same order of magnitude, large topological differences were observed, which could possibly be ascribed to the differences between the surface structures of the two minerals. Negative values of the potential are located above the basal oxygen and at the center of the tetrahedral ring; above silicon the potential is always positive. The value of the potential minimum above the center of the tetrahedral ring of pyrophyllite is ?0.05 V (at 2 Å from the surface), whereas in the case of talc the minimum is ?0.01 V, at 2.7 Å. In the case of pyrophyllite the minimum of potential above the higher basal oxygen is located at 1.1 Å and it has a value of ?1.25 V, whereas above the lower oxygen the value of the potential at the minimum is ?0.2 V, at 1.25 Å; the talc exhibits a minimum of ?0.75 V at 1.2 Å, above the basal oxygen.     

Stabilization of complex ions by the crystal field: CO 3 2− , NO 3 − , O 3 − , [(OH)4]4−, [(OH)3F]4−, [(OH)2F2]4−

According to Koopmans' theorem, only the electrons associated with molecular levels of negative energy are stable. Many ions which cannot exist in the isolated state because certain occupied levels are positive, become stable in crystals under the stabilization effect arising from the crystal field. As examples, we have studied CO ₃ ^2? in calcite, NO ₃ ^? in NaNO₃, and several natural limpurities: O ₃ ^? in fluorite, [(OH)₄]^4?, [(OH)₃F]^4? and [(OH)₂F₂]^4? in zircon and thorite, by means of the molecular self-consistent field, the crystal field being simulated by point charges. As expected, all the energies corresponding to the occupied levels are negative within the crystal field, contrary to what occurs in the isolated state. Informations concerning the structure and the size of the critical germ are obtained for CaCO₃ and NaNO₃.     

[BO_3]、[BO_4]的平衡几何构型和单电子性质的理论研究

本文利用分子轨道理论从头计算法(ab initio)、半经验的MNDO法、多重散射X_α方法(MS-X_α)对[BO_3]、[BO_4]阴离子基团进行了理论研究,计算了它们的平衡几何构型、伸缩振动力常数和振动频率、单电子性质(主要是四极耦合常数),取得了比较令人满意的结果。     

Die Kristallstruktur von Brenkit,Ca2F2CO3

Zusammenfassung Brenkit, Ca₂F₂CO₃, kristallisiert in der RaumgruppePbcn mita=7,650(2),b=7,550(2) undc=6,548(2) Å. Die Kristallstruktur wurde bis zu einemR-Wert von 0,023 für 840 unabhängige Reflexe verfeinert. Kalzium ist unregelmäßig von vier Fluor-und drei Sauerstoff-Atomen koordiniert mit mittleren Ca-F und Ca-O-Abständen von 2,388 Å bzw. 2,426 Å. Die CO₃-Gruppe ist vollständig eben mit C-O-Abständen von 1,279 (2×) und 1,297 Å.

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The crystal structure of Brenkite, Ca₂F₂CO₃

Summary Brenkite crystallizes in space groupPbcn witha=7.650(2),b=7.550(2),c=6.548(2) Å. The crystal structure has been refined toR=0.023 for 840 unique reflections. Calcium is irregularly coordinated by four flourine and three oxygen atoms with mean distances Ca-F and Ca-O of 2.388 and 2.426 Å respectively. The CO₃-group is planar with C-O-distances of 1.279 (2×) and 1.297 Å.

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Die Kristallstruktur des Voltaits,K2Fe 5 2+ Fe 3 3+ Al[SO4]12·18H2O

Zusammenfassung Die Kristallstruktur von künstlichem Voltait, K₂Fe₅ ²⁺Fe₃ ³⁺Al[SO₄]₁₂· ·18 H₂O, kubisch hexakisoktaedrisch,Fd3c–O _h ⁸,a ₀=27,254 ,Z-16, wurde mittels photographischer Röntgendaten bestimmt. Die Aufklärung der Struktur erfolgte mit Patterson- und Fouriermethoden unter Zuhilfenahme des multiplen isomorphen Ersatzes. Die Verfeinerung nach der Methode der kleinsten Quadrate ergab mit anisotropen Temperaturfaktoren für 726 beobachteteF _hkl R=0,033. Das Hauptmerkmal der Struktur ist ein 3dimensionales Gerüst aus [Fe³⁺O₆]-Oktaedern, [Fe ₅ ^6/2+ Fe ₁ ^6/3+ O₄(H₂O)₂]-Oktaedern und [K⁺O₁₂]-Polyedern, die durch SO₄-Tetraeder verknüpft werden. Hohlräume dieses Gerüstes werden von ungeordnet orientierten [Al(H₂O)₆]-Oktaedern eingenommen. Es wird gezeigt, daß Al als wesentlicher Bestandteil dieses Voltaits angesehen werden muß.

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The crystal structure of voltaite, K₂Fe₅ ²⁺Fe₃ ³⁺Al[SO₄]₁₂·18H₂O

Summary The crystal structure of synthetic voltaite, K₂Fe₅ ²⁺Fe₃ ³⁺Al[SO₄]₁₂· · 18 H₂O, cubic hexakis-octahedral, space groupFd3c–O _h ⁸,a ₀=27.254 ,Z=16, was determined from photographic X-ray data. The structure was solved by Patterson and Fourier-methods with the aid of multiple isomorphic substitution. Least squares refinement with anisotropic temperature factors resulted inR=0.033 for 726 observedF _hkl . The dominant structural feature is a continous framework composed of [Fe³⁺O₆]-octahedra, [Fe ₅ ^6/2+ Fe ₁ ^6/3+ O₄(H₂O)₂]-octahedra and [K⁺O₁₂]-polyhedra linked by SO₄-tetrahedra. The arrangement gives rise to cages occupied by disordered [Al(H₂O)₆]-octahedra. It is shown that Al must be considered to be a essential constituent of such voltaites.

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我国发现的一种含锂新矿物——纤钡锂石 BaMg2LiAl3[Si2O6]2（OH）8

纤钡锂石产于湖南临武香花岭地区一水晶矿锂云母石英脉晶洞中,与锂云母、石英等矿物共生。矿物为浅黄白色,丝绢光泽,呈针状、纤维状、放射状或平行束状集合体,纤维长达1厘米。经X射线单晶及粉晶衍射测定:该矿物属斜方晶系,空间群Ccca,晶胞参数:a=13.60(?),b=20.24(?),e=5.16(?)。最强衍射线为:10.12(?)(100) 4.05(?)(78) 3.39(?)(91) 2.605(?)(31)2.390(?)(28)。     

Die Kristallstruktur eines unbenannten zeolithartigen Telluritminerals, {(Zn,Fe)2[TeO3]3}NaxH2−x·yH2O

Zusammenfassung Die Kristallstruktur eines vonJ. A. Mandarino undS. J. Williams (1961) beschriebenen, bisher unbenannten Tellurminerals mit der Raumgruppe P 6₃/m und den Gitterkonstanten a₀=9,41Å, c₀=7,64Å wurde mit dreidimensionalen Patterson-, Fourier-und (F₀–F_c)-Synthesen und einer Least-squares-Verfeinerung bestimmt und verfeinert. Unter Zugrundelegung einer halbquantitativen Mikrosondenanalyse wurde durch die Strukturbestimmung gezeigt, daß es sich um ein zeolithartiges Telluritmineral mit einem negativ geladenen Gerüst {Zn₂[TeO₃]₃} handelt, das parallel [00.1] verlaufende, große offene Kanäle zeigt, die mit Kationen und H₂O statistisch besetzt sind. Die Elementarzelle enthält zwei Formeleinheiten {(Zn,Fe)₂[TeO₃]₃}Na_x H_2–x·yH₂O. Je zwei über Flächen verknüpfte Sauerstoffkoordinationsoktaeder um (Zn,Fe) werden über Ecken mit TeO₃-Pyramiden verknüpft und reihenförmig parallel [00.1] angeordnet. Diese Reihen werden untereinander über die dritte Ecke der TeO₃-Pyramiden zu einem bienenwabenartigen Gerüst verbunden, dessen Kanäle einen Durchmesser von 8,28 Å besitzen.

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Summary The crystal structure of an unnamed hexagonal tellurium mineral, described formerly byJ. A. Mandarino andS. J. Williams (1961) with space group P 6₃/m and lattice constants a₀-9,41 Å, c₀=7,64 Å has been determined and refined by 3-dimensional Patterson-, Fourier-, and (F₀–F_e)-syntheses, and by leastsquares-refinement. Based on a semiquantitative electron microprobe analysis, the structure determination has shown that the described mineral is a zeolite-like tellurite with a negative charged framework {Zn₂[TeO₃]₃} with large open channels running parallel [00.1], which are statistically occupied by cations and H₂O. The unit cell contains two formula units {(Zn,Fe)₂[TeO₃]₃} Nax H_2–x·yH₂O. Two oxygen octahedrons coordinating (Zn,Fe) share faces and are linked by TeO₃-pyramids sharing corners, to form an array parallel [00.1]. These arrays are linked by the third corner of TeO₃-pyramids and form a hexagonal honeycomb-like framework, the channels having a diameter of 8,28 Å.

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Von der mathematisch-Naturwissenschaftlichen Fakultät der Georg-August-Universität zu Göttingen im Februar 1967 angenommene Dissertationsschrift.     

Der Strukturtyp von Emmonsit, {Fe2[TeO3]3·H2O}·xH2O (x=0−1)

Zusammenfassung Emmonsit kristallisiert triklin, RaumgruppeP , Gitterkonstanten:a ₀=7,90 Å,b ₀=8,00 Å,c ₀=7,62 Å, =96^o44, =95^o 0, =84^o 28,Z=2. Der Strukturtyp wurde aus 3-dimensionalen photographischen Röntgendaten ermittelt. Die Eisenatome werden je von 6 Sauerstoffen verzerrt oktaedrisch koordiniert. Jedes Telluratom wird von 3 Sauerstoffen in einem Abstand <2,0 Å umgeben. Ein vierter Sauerstoff hat bezüglich dieser drei einen um etwa 25–35% größeren Abstand, so daß jedes Telluratom im weiteren Sinne eine (3+1)-Koordination aufweist.

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The structure type of emmonsite, {Fe₂[TeO₃]₃·H₂O}·xxH₂O (x=0–1)

Summary Emmonsite is triclinic with space groupP , and lattice constantsa ₀=7.90 Å,b ₀=8.00 Å,c ₀=7.62 Å, =96^o 44, =95^o 0, =84⁰ 28,Z=2. The structure type is derived from 3-dimensional photographic X-ray data. The iron atoms are coordinated by six oxygens in the form of a distorted octahedron. Each tellurium atom is coordinated to 3 oxygens at a distance <2.0 Å. Compared with these 3 Te–O distance the distance of a fourth oxygen is only 25 to 35% greater; therefore each tellurium atom has a (3+1)-coordination of oxygens.

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