Untersuchungen zum ternären System V/Mo/O

Investigation on the Ternary System V/Mo/O During chemical transport reactions mixtures of pseudo-binary line of intersection V₂O₅/MoO₃ are separated into two phases, the V₂O₅-(α) phase, which MoO₃-content depends on the oxygen partial pressure during the deposition and the MoO₃ phase which contains no more than 1% (n/n) V₂O₅. Ternary compounds do not exist on the pseudo-binary line. V₉Mo₆O₄₀ is formed by the reaction of V₂O₅ and MoO₃ (3:2) under exclusion of oxygen. The compound may be chemically transported under the own oxygen coexistence pressure. It was shown by total pressure measurements of V₂O₅/MoO₃ starting mixtures that the insertion of MoO₃ in the α-phase and the formation of the V₉Mo₆O₄₀ phase respectively is connected with elimination of oxygen and the reduction of V^V to V^IV in equivalence of the quantity of incorporated MoO₃.     

Zum System Zn/Mo/O. II. Chemischer Transport ternärer Zinkmolybdate

On the System Zn/Mo/O. II. Chemical Transport of Ternary Zinc Molybdates The Chemical Transport is a method for preparation of phasepure multinary compounds with defined composition. We report about the possibilities to transport ternary compounds of the Zn/Mo/O system using Cl₂, HCl, Br₂, HBr, and I₂ as an agent. The influence of the solid-gas equilibria on the compositions of solids, the transport direction, and the rate is showed.     

Zum System Zn/Mo/O. I. Phasenbestand und Eigenschaften der ternären Zinkmolybdate; Struktur von Zn3Mo2O9

On the System Zn/Mo/O. I. Phases and Properties of Ternary Zinc Molybdates; Crystal Structure of Zn₃Mo₂O₉ Several ternary compounds are known in the Zn/Mo/O-system. The phases ZnMoO₄, Zn₂Mo₃O₈ and Zn₃Mo₂O₉ are stable at 900°C. The coexistence ranges are shown in the ternary phase diagram. The structure of Zn₃Mo₂O₉ has been determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P2₁/m (a = 7,757(1) Å, b = 7,132(1) Å, c = 8,370(2) Å, β = 117,40(1)º, Z = 2).     

Synthese,Eigenschaften und Kristallstruktur von Cu3Mo8O23X2 (X = Cl,Br, I)

Synthesis, Properties, and Crystal Structure of Cu₃Mo₈O₂₃X₂ (X = Cl, Br, I) Single crystals of the Cu₃Mo₈O₂₃X₂ compounds were grown by chemical transport reactions at the lower temperature of a gradient 873–823 K without extra transport agent (auto transport). As DTA/TG measurements indicate, the gaseous compounds, necessary for chemical transport reactions, are formed by partial decomposition of Cu₃Mo₈O₂₃X₂ at 873 K. Cu₃Mo₈O₂₃Br₂ crystallizes with the orthorombic space group Pbcm (a = 4.021(1), b = 22.978(2), c = 21.673(2) Å, Z = 4). The crystal structure consists of pentagonal columns ¹_∞[Mo₆O₇O_20/2] linked by additional MoO_6/2 octahedra. All the polyhedra(pentagonal bipyramide, octahedra) are distorted. Infinite chains ¹_∞[Cu₃Br₂] along [100] are arranged in tunnels with s‐like square shape, left open by the pentagonal columns. Cu₃Mo₈O₂₃Cl₂ (a = 4.010(1), b = 22.942(2), c = 21.639(2) Å) and Cu₃Mo₈O₂₃I₂ (a = 4.052(1), b = 23.075(2), c = 21.719(2) Å) are isotypic.     

Chemischer Transport ternärer Oxide in den Systemen Ca/Mo/O und Sr/Mo/O

Chemical Vapour Transport of Ternary Oxides in the Systems Ca/Mo/O and Sr/Mo/O The chemical vapour transport behaviour of ternary phases in the Ca/Mo/O and Sr/Mo/O systems has been investigated using Cl₂ as transport agent in a temperature gradient 1423 to 1323 K. MMoO₄ (M= Ca, Sr) migrate in the above‐mentioned temperature gradient with rates of 0.1 to 0.2 mg/h. Starting from three phase mixtures crystals of the compounds MMo₅O₈ have been grown (migration rates: M = Ca 0.1 mg/h, M = Sr 0.01 mg/h). The observed transport behaviour is compared with predictions given by thermo dynamical model calculations and the influences of source composition and the moisture contents are described in detail.     

Zum Chemischen Transport im System Mn/Mo/O

Chemical Transport Reactions in the System Mn/Mo/O For the ternary system Mn/Mo/O the phasepure preparation of the compounds MnMoO₄ and Mn₂Mo₃O₈ by chemical transport is reported. The deposition from a source of coexisting threephase mixtures give the possibility to prepare single crystals under defined oxygen partial pressure. The influence of different startmixtures and the agents Cl₂, HCl, I₂, HI, TeCl₄ and SeCl₄ on the transport behaviour are described. Results hitherto existing for the single crystals give hints of only very small homogeneity ranges for both phases.     

Darstellung,Eigenschaften und Phasenbeziehungen von Ru3Sn15O14

Preparation, Properties, and Phase Relations of Ru₃Sn₁₅O₁₄ Coexistence relations in the system Ru/Sn/O have been investigated by X‐ray measurements of powder mixtures annealed in the region of 1173–1273 K. Thermodynamic data of Ru₂Sn₃, Ru₃Sn₇, and Ru₃Sn₁₅O₁₄ were obtained by EMF measurements. Phase diagrams calculated with these data are in good agreement with experimental results. Only one phase, Ru₃Sn₁₅O₁₄, exists in the ternary system between 973 and 1273 K. Red translucend single crystals were obtained from a tin melt. Polycrystalline powder was prepared by solid state reaction of a mixture of Ru₃Sn₇, SnO₂, and Sn with molar ratio 1:7:1 at 1173 K. Ru₃Sn₁₅O₁₄ is a p‐type semiconductor, E_A = 0.50(5) eV, as conductivity and thermopower measurements show. Mössbauer investigations confirm the existence of three different tin surroundings.     

Der Chemische Transport ternärer intermetallischer Phasen in den Systemen Cr/Co/Ge und Co/Ta/Ge

Chemical Vapor Transport of Intermetallic Systems. 11 Chemical Vapor Transport of Ternary Intermetallic Phases in the Systems Cr/Co/Ge and Co/Ta/Ge By means of chemical vapor transport using iodine as transport agent it is possible to prepare a number of ternary intermetallic compounds in the system Co/Cr/Ge as single crystals. The transport behaviour in this ternary system is related to that in the binary systems. Some informations are given about transport phenomena in the systems Co/Cr and Co/Ta/Ge.     

Darstellung,Kristallstruktur und elektronenmikroskopische Untersuchung von UNb6O16 – einem neuen niobreichen Oxid im System U/Nb/O

Preparation, Crystal Structure and Electron Microscopic Investigation of UNb₆O₁₆ – a New Niobium-rich Phase in the System U/Nb/O Powdery UNb₆O₁₆ was produced by heating (1 000°C or 1 100°C; evacuated silica tube) mixed powders of UO₂, NbO₂ and Nb₂O₅ (1:2:2). Single-crystals of UNb₆O₁₆ were obtained by chemical transport in a small temperature gradient (1 000°C → 990°C; transport agent NH₄Cl). The lattice constants are a = 22 339(4) Å; b = 3.7750(6) Å; c = 7.249(3) Å; β = 97.61(3)° and Z = 2. The structure determination (space group C2) let to R = 0.026 (R_w = 0.026). Eight oxygen atoms surround U⁴⁺ like a trans-bis-capped octahedron, Nb⁴⁺ and Nb⁵⁺ are coordinated distorted octahedraly. The structure was checked and the occupation of the positions O8 and O9 was clarified with the program MAPLE4 [3]. A through focus series of high resolution transmission electron microscopic images was obtained which is in acceptable agreement with images calculated on the basis of the multi-slice method.     

Zu den Phasenverhältnissen im System V/Nb/O. I. Koexistenzbeziehungen im Bereich V2O5/Nb2O5/VO2/NbO2

The Phase Relations in the System V/Nb/O. I. Coexistence Relations in the Section V₂O₅/Nb₂O₅/VO₂/NbO₂ . Phase relations in the section Nb₂O₅/V₂O₅/VO₂/NbO₂ of the ternary system V/Nb/O have been studied by X-ray diffraction. The investigated samples were prepared by high temperature synthesis at 900°C–1000°C. The section Nb₂O₅/V₂O₅/VO₂/NbO₂ is charakterized by fife three phase regions: The limits of solubility of the pseudobinary system were ascertained by determination of lattic parameters of powder samples:      

Zum Chemischer Transport ternärer Übergangsmetall‐ und Erdalkaliwolframate MWO4 mit Chlor

On the Chemical Vapor Transport of Ternary Transition Metal‐ and Earth Alkaline Tungstates MWO₄ with Chlorine The chemical vapor transport of transition metal tungstates MWO₄ (M=Mn, Co, Ni, Cu, Zn, Cd) was investigated in dependence on mean transport temperature (923 K to 1223 K) and amount of transport agent Cl₂. All tungstates migrate in a temperature gradient ΔT = 100 K from the region of higher temperature to the lower temperature with migration rates of 0.5 to 8 mg/h depending on experimental conditions. The transport behaviour was determined by continuous measurement of mass change during the transport experiments. The results were compared to thermo chemical calculations and the influence of moisture content discussed in detail. MgWO₄ migrates under the influence of Cl₂ in a temperature gradient 1273 K to 1173 K (migration rate 0.7 mg/h), CaWO₄ and SrWO₄ in a temperature gradient 1423 K to 1323 K (migration rate <0.1 mg/h).     

Thermochemische Untersuchungen im System V/Nb/O. II Zum chemischen Transportverhalten im Bereich V2O5/Nb2O5/VO2/NbO2

Thermochemical Investigations in the System V/Nb/O. II. Chemical Transport in the Region V₂O₅/Nb₂O₅/VO₂/NbO₂ Transport experiments were used to support the phase relationships of the V₂O₅/Nb₂O₅/VO₂/NbO₂ system, which were established by annealing experiments of powder mixtures. The phase relations were studied in the NbO₂-rich region of the system by means of X-ray and ESMA methods. The NbO₂-rich section is characterized by the following two phase and three phase regions: Two phase region: V₃Nb₉O₂₉/rutile mixed crystal V_1?xNb_xO₂ Two phase region: BI-mixed crystal/V_xNb_1?xO₂ Three phase region: V₃Nb₉O₂₉/solubility limit LG1 (V_1?xNb_xO₂)/BI-mixed crystal Three phase region: solubility limit LG1 (V_1?xNb_xO₂)/BI-mixed crystal/solubility limit LG2 (V_xNb_1?xO₂). The composition of the solubility limits LG1 and LG2 was ascertained by means of ESMA-investigation: LG1: 57.5 ± 5 mol% NbO₂/43.5 ± 5 mol% VO₂ LG2: 22.5 ± 5 mol% NbO₂/78.5 ± 5 mol% VO_2?     

Zur thermischen Zersetzung von TeSeO4 und Te3SeO8 – Koexistenzbeziehungen im ternären System TeO2/SeO2/Bi2SeO5

Thermal Decomposition of TeSeO₄ and Te₃SeO₈ – Phase Relations in the Ternary System TeO₂/SeO₂/Bi₂SeO₅ The saturation decomposition pressure of TeSeO₄ and Te₃SeO₈ were determined in a membran zero manometer. From the equilibrium data are derived the Enthalpies of formation and the Standard Entropies: Data see Inhaltsübersicht. Thus the coexistence ranges in the ternary triangle TeO₂/SeO₂/Bi₂SeO₅ can be determined. Informations about the melting diagram obtained by thermal analysis of the condensed compositions TeO₂/SeO₂.     

Mischkristallbildung im System CuMoO4/ZnMoO4

Mixed Crystals in the System CuMoO₄/ZnMoO₄ The existence of a complet solid solution serie Cu_1–xZn_xMoO₄ (0 ≤ x ≤ 1) is confirmed. Single crystals were obtained by chemical transport with different transport agents. The compositions and structures were characterized by EDX analysis, photometic analysis, and X‐ray investigations on polycrystallin powders and single crystals. The substitution behaviour of (Cu_1–xZn_x)O₆‐ and (Cu_1–xZn_x)O₅‐polyhedra is different and the reason for deviations from the Vegards rule are near x = 0.25.     

Der Chemische Transport von Kupfer/Gallium‐ und Silber/Gallium‐Phasen

Chemical Vapor Transport of Intermetallic Systems. 10. Chemical Transport of Copper/Gallium and Silver/Gallium Phases The solid solution of gallium in copper and the ζ‐ and the γ‐phase can be prepared by CVT‐methods using iodine as transport agent. The solid solution of gallium in silver and the ζ‐phase and the ζ′‐phase can also prepared by CVT‐methods. Thermodynamic calculations allow to understand why these phases can be prepared by this manner.     

Untersuchungen zur Reaktivität in den Systemen A/Cu/M/O (A = Na–Cs und M = Co,Ni, Cu,Ag); Synthese und Kristallstrukturen von K3Cu5O4 und Cs3Cu5O4

Reactivity in the Systems A/Cu/M/O (A = Na–Cs and M = Co, Ni, Cu, Ag); Synthesis and Crystal Structures of K₃Cu₅O₄ und Cs₃Cu₅O₄ The systems A/Cu/M/O with A = Na–Cs and M = Co, Ni, Cu, Ag have been investigated with preparative, thermoanalytical and in situ X‐ray techniques to study the reactivity. For the redox reaction Co/CuO in the presence of Na₂O the intermediate, NaCuO, has been characterized. K₃Cu₅O₄ was obtained by annealing intimate mixtures of K₂O and CuO (molar ratio 1 : 1) in Ag containers at 500 °C. Cs₃Cu₅O₄ could be synthezised by reaction of KCuO₂ with Cs₂O (molar ratio 1 : 1) in Cu containers at 500 °C. Both compounds crystallize in the space group P2₁/c with Z = 4 isotypic to Rb₃Cu₅O₄ [IPDS data, Mo–Kα; K₃Cu₅O₄: a = 946.0(1), b = 735.61(6), c = 1401.3(2) pm, β = 107.21(1)°; 2249 F²(hkl), R₁ = 7.09%, wR₂ = 11.42%; Cs₃Cu₅O₄: a = 1027.7(1), b = 761.42(7), c = 1473.4(2) pm, β = 106.46(1)°, 1712 F²(hkl), R₁ = 6.04%, wR₂ = 14.22%]. Force constants obtained from FIR experiments for the deformation mode δ(O–Cu–O), the Madelung Part of the Lattice Energie, MAPLE, Effective Coordination Numbers, ECoN, calculated via Mean Effective Ionenradii, MEFIR, are given.     

Chemischer Transport intermetallischer Phasen Der chemische Transport von Mischkristallen im System Cu/Ag

Chemical Vapor Transport of Intermetallic Systems Chemical Transport of Cu/Ag-mixed Crystals By means of chemical transport reaction it is possible to prepare Cu-rich and Ag-rich mixed crystals in the Cu/Ag system. The composition of individual deposited crystals was different. Mass-spectrometric analysis of the gas-phase above CuI/AgI has shown the formation of CuAg₂I_3,g und Cu₂AgI_3,g. Thermodynamic computations explain the formation of crystals as well as the reaction conditions.     

Kristallstrukturen und spektroskopische Untersuchungen ternärer CuII-Komplexe mit bicyclischen Dicarbonsäuren und N,N-Donor-Liganden

Crystal Structures and Spectroscopic Investigations of Ternary Cu^II-Complexes with Bicyclic Dicarboxylic Acids and N,N-Donor Ligands The synthesis of coordination compounds [CuLdam] · 3H₂O (H₂L = 7-oxa-bicyclo[2.2.1]heptane-2-exo,3-cis-dicarboxylic acid ( 1 ) and its 1-methyl-derivative ( 2 ); dam = ethylendiamine, 1,2- and 1,3-propylendiamine, 2,2′-dipyridyl, 1,10-phenanthroline) has been described. Results of visible and IR spectroscopy and magnetic data are given. In the result of X-ray analyses of [CuL¹dipy] · 3H₂O ( 1 d ) and [CuL²en] · 3H₂O ( 2 a ) the dicarboxylate anions of 1 and 2 proved to be tridentate chelating ligands. In 1 d the Cu atom has an approximately square-pyramidal coordination with the bridging O atom in the apical position. In 2 a , however, the coordination number is extended to six by an O atom of a second [CuL²en] unit resulting in a centrosymmetric complex dimer with octahedrally coordinated Cu atoms. The water molecules do not participate in the coordination of the Cu atoms and form a complicated system of hydrogen bonds in the crystal.