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1.
The new mixed oxide having composition close to Ca7Co3Ga5O18 was synthesized from CaCO3, Co3O4 and Ga2O3 at 1150 °C in air and studied by neutron and synchrotron X-ray powder diffraction, selected-area electron diffraction and high-resolution electron microscopy. The structure was refined, using time-of-flight (TOF) neutron powder diffraction data, in space group F432, with and Z=8, to RF=0.7%. It is considerably disordered, with four different tetrahedral sites randomly occupied by Co and Ga atoms at a ratio of 1:2. The tetrahedra form a disordered (Co1/3Ga2/3)O2 3D-framework inside which isolated CoO6 octahedra, surrounded by 8 Ca atoms, are located. The structure is related to the ordered structure of Ca14Al10Zn6O35. Electron diffraction patterns confirmed the symmetry and unit cell and revealed no diffuse scattering. High-resolution electron microscopy images showed the absence of extended structural defects.  相似文献   

2.
Crystals of PbCu3(OH)(NO3)(SeO3)3·1/2H2O [a=7.761(3)Å,b=9.478(4)Å,c=9.514(4)Å, =66.94(2)°, =69.83(2)°, =81.83(2)°, space group P ,Z=2] and Pb2Cu3O2(NO3)2(SeO3)2 [a=5.884(2)Å,b=12.186(3)Å,c=19.371(4)Å, space group Cmc21,Z=4] were synthesized under hydrothermal conditions. Their crystal structures were refined with three-dimensional X-ray data toR w=0.033 resp. 0.055. In PbCu3(OH)(NO3)(SeO3)3·1/2H2O the Cu atoms are [4+1] and [4+2] coordinated and via SeO3 groups a three-dimensional atomic arrangement is built up. In Pb2Cu3O2(NO3)2(SeO3)2 there are sheets, which are connected only via Pb-O bonds ranging from 2.98 Å to 3.16 Å.
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3.
4.
CoNb2O6 can be prepared by reaction of stoichiometric amounts of CoO (thermical decomposition of cobaltoxalate) and Nb2O5 in argon-atmosphere up to 1,400 °C. The isolated red-brown single crystals have tetragonal symmetry (a=472.6;c=305.4 pm; space group P42/mnm-D 4h 14 ). Electron probe micro-analysis of the single crystals verifies the composition Co0.33Nb0.67O2. Co2+ and Nb5+ occupy statistically the metal positions of the rutil-type structure. The differences between Co0.5Nb0.5O2 (CoNbO4AlNbO4-type) and Co0.38Nb0.67O2 (CoNb2O6) are discussed.
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5.
Mo2Cl4 Pic 4·CHCl3 (A) (Pic=4-methylpyridine) and Mo2Br4 Pic 4 (B) crystallize in the monoclinic space group.A inC2/c (No. 15) witha=15.175 (4),b=10.847 (2),c=19.946 (6) and =104.52 (2)°;D o=1.71 (2),D c =1.72 gcm–3 forZ=4.B inP2l/n (No. 14) witha=9.270 (3),b=16.614 (5),c=9.305 (3) and =91.96 (5)°;D o=2.03 (3),D c =2.05 gcm–3 forZ=2.Two halogens and 4-methylpyridines of the MoX 2 Pic 2 group are in the trans position. Mo–Mo bond lengths are 2.153 96) forA and 2.150 92) forB. Both molecules are situated on the inversion center resulting in the eclipsed configuration of the ligands around the molybdenum pair. The structure ofB has been refined to the conventionalR factors of 0.08 and 0.098. Disorder on the part of 4-methylpyridines and chloroform molecules stopped the refinement ofA at the endR value of 0.175.Mean Mo–X and Mo–N bonding distances are 2.40 (2), 2.25 (5) forA and 2.53 (3), 2.25 (1) forB.
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6.
The three copper(II)-arsenates were synthesized under hydrothermal conditions; their crystal structures were determined by single-crystal X-ray diffraction methods:Cu3(AsO4)2-III:a=5.046(2) Å,b=5.417(2) Å,c=6.354(2) Å, =70.61(2)°, =86.52(2)°, =68.43(2)°,Z=1, space group ,R=0.035 for 1674 reflections with sin / 0.90 Å–1.Na4Cu(AsO4)2:a=4.882(2) Å,b=5.870(2) Å,c=6.958(3) Å, =98.51(2)°, =90.76(2)°, =105.97(2)°,Z=1, space group ,R=0.028 for 2157 reflections with sin / 0.90 Å–1.KCu4(AsO4)3:a=12.234(5) Å,b=12.438(5) Å,c=7.307(3) Å, =118.17(2)°,Z=4, space group C2/c,R=0.029 for 1896 reflections with sin / 0.80 Å–1.Within these three compounds the Cu atoms are square planar [4], tetragonal pyramidal [4+1], and tetragonal bipyramidal [4+2] coordinated by O atoms; an exception is the Cu(2)[4+1] atom in Cu3(AsO4)2-III: the coordination polyhedron is a representative for the transition from a tetragonal pyramid towards a trigonal bipyramid. In KCu4(AsO4)3 the Cu(1)[4]O4 square and the As(1)O4 tetrahedron share a common O—O edge of 2.428(5) Å, resulting in distortions of both the CuO4 square and the AsO4 tetrahedron. The two Na atoms in Na4Cu(AsO4)2 are [6] coordinated, the K atom in KCu4(AsO4)3 is [8] coordinated by O atoms.Die drei Kupfer(II)-Arsenate wurden unter Hydrothermalbedingungen gezüchtet und ihre Kristallstrukturen mittels Einkristall-Röntgenbeugungsmethoden ermittelt:Cu3(AsO4)2-III:a = 5.046(2) Å,b = 5.417(2) Å,c = 6.354(2) Å, = 70.61 (2)°, = 86.52(2)°, = 68.43(2)°,Z = 1, Raumgruppe ,R = 0.035 für 1674 Reflexe mit sin / 0.90 Å–1.Na4Cu(AsO4)2:a = 4.882(2) Å,b = 5.870(2) Å,c = 6.958(3) Å, = 98.51(2)°, = 90.76(2)°, = 105.97(2)°,Z = 1, Raumgruppe ,R = 0.028 für 2157 Reflexe mit sin / 0.90 Å–1.KCu4(AsO4)3:a = 12.234(5) Å,b = 12.438(5) Å,c = 7.307(3) Å, = 118.17(2)°,Z = 4, Raumgruppe C2/c,R = 0.029 für 1896 Reflexe mit sin / 0.80 Å–1.Die Cu-Atome in diesen drei Verbindungen sind durch O-Atome quadratisch planar [4], tetragonal pyramidal [4 + 1] und tetragonal dipyramidal [4 + 2]-koordiniert; eine Ausnahme ist das Cu(2)[4 + 1]-Atom in Cu3(AsO4)2-III: Das Koordinationspolyeder stellt einen Vertreter des Übergangs von einer tetragonalen Pyramide zu einer trigonalen Dipyramide dar. In KCu4(AsO4)3 haben das Cu(1)[4]O4-Quadrat und das As(1)O4-Tetraeder eine gemeinsame O—O-Kante von 2.428(5) Å, was eine Verzerrung der beiden Koordinationsfiguren CuO4-Quadrat und AsO4-Tetraeder bedingt. Die zwei Na-Atome in Na4Cu(AsO4)3 sind durch O-Atome [6]-koordiniert, das K-Atom in KCu4(AsO4)3 ist [8]-koordiniert.
Zur Kristallchemie dreier Kupfer (II)-Arsenate: Cu3(AsO4)2-III, Na4Cu(AsO4)2 und KCu4(AsO4)3
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7.
The dynamics of elementary rate processes for H+O2 collisions on an ab initio potential energy surface have been simulated by quasiclassical trajectory theory (QCT). For H+O2 (v=0,j=1), we have obtained the reaction probabilityP r (E,b) as a function of collision energy E and impact parameterb, the reaction cross sectionS r as a function ofE, and the average values of the product quantum numbers of OH.For H+02 (v=2,j=1, 20, 40, 60, 80, 100;v=1, 3, 4, 5,j=1) atE=0.3 eV, we have found thatb max is about 4.5a 0 and the impact parameter at whichP r is maximum decreases asj increases. The reaction cross section increases asj andv become large. For inelastic collisions, whenb is small andj is large, the and are both small. For reactive collisions, almost equals zero, but the probability of being larger than zero increases with increasingj; and¯v OH even shows population inversion forj=100. Additional details of the dynamics are shown in figures of interparticle distance and stereographs.  相似文献   

8.
The crystal structure of the new phase Cu7(OH)6(TeO3)2(SO4)2 [a=7.389 (1),b=7.638 (1),c=7.662 (2) Å, =75.17 (1), =75.90 (1), =84.19 (1)°;Z=1] was determined by direct methods andFourier summations from X-ray intensities, and was refined in space group P -C i 1 toR=0.039. As usual, the Cu(II) atoms are coordinated to four O atoms forming approximately a square with average Cu-O=1.96 (3) Å; one or two more distant O neighbours complete the coordination. The shape of the TeO3 group is a rather clear-cut trigonal pyramid. A disorder was found for the SO4 tetrahedra. The compound was synthesized under hydrothermal conditions [500 (10) K, saturation vapour pressure].
Herrn Prof. Dr.K. Komarek zum 60. Geburtstag gewidmet.  相似文献   

9.
Novel complex oxides Ca14Zn6Ga10O35 and Ca14Zn5.5Ga10.5O35.25 were prepared in air at 1200 °C, 72 h. Refinements of their crystal structures using X-ray powder diffraction data showed that Ca14Zn6Ga10O35 is ordered (S.G. F23, =0.0458, Rp=0.0485, Rwp=0.0659, χ2=1.88) and Ca14Zn5.5Ga10.5O35.25 disordered (S.G. F432, =0.0346, Rp=0.0601, Rwp=0.0794, χ2=2.82) variants of the crystal structure of Ca14Zn6Al10O35. In the crystal structure of Ca14Zn6Ga10O35, there are large empty voids, which could be partially occupied by additional oxygen atoms upon substitution of Zn2+ by Ga3+ as in Ca14Zn5.5Ga10.5O35.25. These oxygen atoms are introduced into the crystal structure of Ca14Zn5.5Ga10.5O35.25 only as a part of four tetrahedra (Zn, Ga)O4 groups sharing common vertex. This creates a situation where even a minor change in the chemical composition leads to considerable anion and cation disordering resulting in a change of space group from F23 (no. 196) to F432 (no. 209).  相似文献   

10.
Nonstoichiometric perovskite oxide Ce x Cu3V4O12 (space group Im $ \bar 3 Nonstoichiometric perovskite oxide Ce x Cu3V4O12 (space group Im Z = 2, a = 7.264–7.328 ?) with cationic vacancies was prepared barothermally. This compound has metal-type conductivity, paramagnetic properties, and a phase transition. Original Russian Text ? N.I. Kadyrova, Yu.G. Zainulin, V.L. Volkov, G.S. Zakharova, A.V. Korolev, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 10, pp. 1650–1654.  相似文献   

11.
12.
A new complex compound, bis[(18-crown-6)oxonium]tetrabromomanganese(II), 2[(H3O)+(18-crown-6)]·[MnBr4]2–, was prepared and studied by X-ray diffraction to reveal its unusual cubic crystal structure, space group Fd $ \bar 3 A new complex compound, bis[(18-crown-6)oxonium]tetrabromomanganese(II), 2[(H3O)+(18-crown-6)]·[MnBr4]2–, was prepared and studied by X-ray diffraction to reveal its unusual cubic crystal structure, space group Fd, a 20.424 ?, and Z 8. In this crystal structure, the complex cation [(H3O)+(18-crown-6)] the point symmetry position and the anion [MnBr4]2− with the point symmetry 23. The complex cation [(H3O)+(18-crown-6)] has a guest-host structure, and, unlike metal complexes by hydrogen bonds between H3O+ hydrogens and 18-crown-6 oxygens, rather than by coordination bonds. The pyramidal cation H3O+ in this crystal structure is statistically disordered, and the tetrahedral anion [MnBr4]2− is reorientationally disordered. Original Russian Text ? A.N. Chekhlov, 2008, published in Zhurnal Obshchei Khimii, 2008, vol. 78, No. 10, pp. 1622–1626.  相似文献   

13.
Nanostructured hybrid materials containing Al2O3 were synthesized via a sol-gel method through hydrolysis and co-condensation reactions using trimethylsilyl isocyanate (TMSI) as a new silica source in the presence of tetramethoxysilane (TMOS) and three different quantities (10, 20 and 30 wt.%) of aluminum sec-butoxide (Al(OBusec)3 as a modifying agent. The xerogel nanostructured materials are pyrolyzed in nitrogen atmosphere in the temperature range from 400°C to 1100°C. The transformation of the xerogel hybrid networks into Al-Si oxycarbonitride materials has been investigated by XRD, FTIR, SEM, AFM, and 29Si MAS-NMR. To the best of our knowledge, the work reported here is the first synthesis of porous di-urethanesils modified with aluminum and one of the few examples of alumosilica oxycarbonitride materials   相似文献   

14.
Thermal decomposition of LiPF6 and LiBC4O8 (lithium bis(oxalate)borate, abbreviated as LiBOB) were studied using TG (thermogravimetry)-DTG (derivative thermogravimetry) method with different heating rate β of 5, 10, 20 and 40°C min−1 or at different constant temperature θ C (109·80, 118·79, 148·41, 176·86°C for LiPF6 and 278·51, 298·13, 317·65, 336·13 for LiBOB). From the non-isothermal kinetics we calculate that is 1·01, n LiBOB is 1·04, is 91907·61 J/mol, and E LiBOB is 205179·88 J/mol; from the isothermal kinetics we calculate that n for both LiPF6 and LiBOB are 1, ELiPF6 is 91907·61 J/mol, E LiBOB is 205179·88 J/mol, is 16·89 s−1, and lnALiBOB is 31·96 s−1. The results obtained from the two ways have minor differences and can validate each other.  相似文献   

15.
By means of thermogravimetry (TG) and chemical analysis equilibrium dependencies of oxygen content in GdBa2Cu3O6+x and HoBa2Cu3O6+x on temperature and were studied. It is found that at equal temperature and the oxygen content in RBa2Cu3O6+x increased in order Ho-Y-Gd.On the basis of Fick 2nd law mathematical procedures to determine diffusion coefficients of oxygen from TG data were developed. The oxygen diffusion coefficients in RBa2Cu3O6+x (R=Y, Gd, Ho) were evaluated in a wide temperature (300–900°C) range (at =0.21 bar). The developed model rather satisfactory decribes oxygen diffusion processes in phases under investigation. It is found that for all studied compounds oxygen diffusion in orthorhombic phase happened faster than in tetragonal one. The values of diffusion coefficients increase in order Ho-Y-Gd with increasing of ionic radius of the rare earth element.  相似文献   

16.
The structure of the “Type III” δ-Bi2O3-related superstructure phase in the system Bi2O3-Nb2O5 is presented. A starting model was constructed by considering the crystal-chemistry of the system in the context of symmetry constraints determined by electron diffraction. After applying initial distortions, this could be Rietveld-refined against a combination of synchrotron X-ray and time-of-flight neutron powder diffraction data. The undistorted starting model was independently optimized using solid-state ab initio energy calculations, giving a fully optimized structure in excellent agreement with that obtained by Rietveld refinement. This dual approach both validates the structure and demonstrates the value of combining accurate total energy calculations with traditional refinement techniques for the solution of complex structures using powder diffraction data. The structure (Bi94Nb32O221, Z=1, (#119), a=11.52156(18), ) consists of interacting corner-connected strings of NbO6 octahedra along 〈110〉F directions of the FCC subcell, and can be described as a hybrid of fluorite and pyrochlore types.  相似文献   

17.
Subsolidus phase relations have been determined for the Bi2O3-Fe2O3-Nb2O5 system in air (900-1075 °C). Three new ternary phases were observed—Bi3Fe0.5Nb1.5O9 with an Aurivillius-type structure, and two phases with approximate stoichiometries Bi17Fe2Nb31O106 and Bi17Fe3Nb30O105 that appear to be structurally related to Bi8Nb18O57. The fourth ternary phase found in this system is pyrochlore (A2B2O6O′), which forms an extensive solid solution region at Bi-deficient stoichiometries (relative to Bi2FeNbO7) suggesting that ≈4-15% of the A-sites are occupied by Fe3+. X-ray powder diffraction data confirmed that all Bi-Fe-Nb-O pyrochlores form with positional displacements, as found for analogous pyrochlores with Zn, Mn, or Co instead of Fe. A structural refinement of the pyrochlore 0.4400:0.2700:0.2900 Bi2O3:Fe2O3:Nb2O5 using neutron powder diffraction data is reported with the A cations displaced (0.43 Å) to 96g sites and O′ displaced (0.29 Å) to 32e sites (Bi1.721Fe0.190(Fe0.866Nb1.134)O7, Fdm (#227), ). This displacive model is somewhat different from that reported for Bi1.5Zn0.92Nb1.5O6.92, which exhibits twice the concentration of small B-type cations on the A-sites as the Fe system. Bi-Fe-Nb-O pyrochlores exhibited overall paramagnetic behavior with large negative Curie-Weiss temperature intercepts, slight superparamagnetic effects, and depressed observed moments compared to high-spin, spin-only values. The single-phase pyrochlore with composition Bi1.657Fe1.092Nb1.150O7 exhibited low-temperature dielectric relaxation similar to that observed for Bi1.5Zn0.92Nb1.5O6.92; at 1 MHz and 200 K the relative permittivity was 125, and above 350 K conductive effects were observed.  相似文献   

18.
Direct synthesis of H2O2 solutions by a fuel cell method was reviewed. The fuel cell reactor of [O2, gas-diffusion cathode electrolyte solutions Nafion membrane electrolyte solutions gas-diffusion anode, H2] is very effective for formation of H2O2. The three-phase boundary (O2(g)–electrode(s)–electrolyte(l)) in the gas-diffusion cathode is essential for efficient formation of H2O2. Fast diffusion processes of O2 to the active surface and of H2O2 to the bulk electrolyte solutions are essential for H2O2 accumulation. The maxima H2O2 concentrations of 1.2 M (3.5 wt%) and 2.4 M (7.0 wt%) were accomplished by the heat-treated Mn-OEP/AC electrocatalyst with H2SO4 electrolyte and by the VGCF electrocatalyst with NaOH electrolyte, respectively, under short circuit conditions.  相似文献   

19.
Summary Single crystal X-ray data of the hydrothermally grown new phase Li2Cu3(SeO3)2(SeO4)2 were measured with a four-circle diffractometer up to sin /=0.81 Å–1 [I2/a,Z=4,V=1175.5 Å3,a=16.293(6),b=5.007(2),c=14.448(6) Å, = 94.21(1)°]. The structure was determined by direct and Fourier methods and refined toR=0.034,R w =0.027 for 2 086 independent reflections.Cu(1)[4+1]O5 forms a tetragonal pyramid, Cu(2)[4 + 2]O6 is a strongly elongated octahedron. The Li atom is surrounded by four O atoms forming a distorted tetrahedron. Se(IV)O3 and Se(VI)O4 groups are in accordance to literature, mean Se-O bond lengths are 1.714 and 1.644 Å.
Die Kristallstruktur von Li2Cu3(SeO3)2(SeO4)2
Zusammenfassung Einkristall-Röntgendaten der hydrothermal gezüchteten neuen Phase Li2Cu3(SeO3)2(SeO4)2 wurden mit einem Vierkreisdiffraktometer im Bereich bis zu sin /=0.81 Å–1 gemessen [I2/a,Z=4,V=1175.5 Å3,a=16.293(6),b=5.007(2),c=14.448(6) Å, =94.21(1)°]. Die Kristallstruktur wurde mittels direkter und Fourier-Methoden bestimmt und für 2 086 unabhängige Reflexe zuR=0.034,R w =0.027 verfeinert.Cu(1)[4+1]O5 bildet eine tetragonale Pyramide, Cu(2)[4+2]O6 ist ein stark verlängertes Oktaeder. Das Li-Atom ist von vier O-Atomen in Gestalt eines verzerrten Tetraeders umgeben. Die Se(IV)O3-und Se(VI)O4-Gruppen entsprechen der Literatur, die mittleren Se-O-Abstände betragen 1.714 und 1.644 Å.
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20.
The subsolidus region of the Cs2MoO4-Bi2(MoO4)3-Zr(MoO4) system was studied by X-ray powder diffraction. Quasi-binary sections were elucidated, and triangulation performed. Triple molybdates with the component ratios 5: 1: 2 (S 1) and 2: 1: 4 (S 2) were prepared for the first time. Crystals of cesium bismuth zirconium molybdate of the 5: 1: 2 stoichiometry (Cs5BiZr(MoO4)6) were grown from fluxed melts with spontaneous nucleation. The composition and crystal structure of this triple molybdate were refined using X-ray diffraction data (collected on X8 APEX automated diffractometer, MoK α radiation, 2348 F(hkl), R = 0.0226). The trigonal unit cell parameters were as follows: a = b = 10.9569(2), c = 39.804(4) Å, V = 4138.4(4) Å3, Z = 6, space group R $ \bar 3 The subsolidus region of the Cs2MoO4-Bi2(MoO4)3-Zr(MoO4) system was studied by X-ray powder diffraction. Quasi-binary sections were elucidated, and triangulation performed. Triple molybdates with the component ratios 5: 1: 2 (S 1) and 2: 1: 4 (S 2) were prepared for the first time. Crystals of cesium bismuth zirconium molybdate of the 5: 1: 2 stoichiometry (Cs5BiZr(MoO4)6) were grown from fluxed melts with spontaneous nucleation. The composition and crystal structure of this triple molybdate were refined using X-ray diffraction data (collected on X8 APEX automated diffractometer, MoK α radiation, 2348 F(hkl), R = 0.0226). The trigonal unit cell parameters were as follows: a = b = 10.9569(2), c = 39.804(4) ?, V = 4138.4(4) ?3, Z = 6, space group R c. The mixed-metal three-dimensional framework in this structure is built of Mo tetrahedra and two sorts of (Bi,Zr)O6 octahedra. Large interstices accommodate two sorts of cesium atoms. The Bi3+ and Zr4+ cation distributions over two positions were refined during structure solution. Original Russian Text ? B.G. Bazarov, T.V. Namsaraeva, R.F. Klevtsova, A.G. Anshits, T.A. Vereshchagina, R.V. Kurbatov, L.A. Glinskaya, K.N. Fedorov, Zh.G. Bazarova, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 9, pp. 1585–1589.  相似文献   

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