Der chemische Transport von Titangermaniden

Chemical Vapor Transport of Intermetallic Systems. 8. Chemical Transport of Titaniumgermanides By means of chemical vapor transport using iodine as transport agent in the System Ti/Ge the compounds TiGe₂ and Ti₅Ge₃ have been prepared in form of single crystals. Unexpectedly the phase Ti₆Ge₅ could not be deposited from the vapor phase. The experiments show in contrast to the literature that Ti₆Ge₅ is at 700 °C thermodynamic unstable. Chemical vapor transport is a suitable method to determine coexistence conditions of intermetallic compounds.     

Der chemische Transport von Lanthanphosphat LaPO4 mit Br-haltigen Systemen

The chemical transport of LaPO₄ (1400 → 1200°K) is discussed on a thermodynamical basis and experimentally checked. Br₂ + PBr₃ used as transport agents give good transportrates. Br₂ + CO and Br₂ + C are also suitable transportsystems. On the other hand Br₂ without additions, caused by an unfavourable equilibrium position gives no measurable LaPO₄-transport. Using HBr as transport agent, the transport rate is small. In addition there are difficulties, caused by the partial decomposition of HBr into the elements and the diffusion of H₂ through the wall of the quartz ampoule. LaPO₄-crystals prepared by chemical transport have the well known monoclinic monazite structure.     

Der chemische Transport von FeP2 und FeP4 mit lod

Chemical Transport of FeP₂ and FeP₄ with Iodine Experiments on the chemical transport of FeP₂ and FeP₄ with iodine are discussed, considering the gaseous molecules I₁, I₂, FeI₂, Fe₂I₄, FeI₃, Fe₂I₆, PI₃, P₂I₄, P₄, P₂, and P. Thermodynamic calculations give δH°(298) = 56.322 kcal and ΔS°(298) = 39.5 cal/K for the reaction FeP_2,f + I₂ = FeI₂ + 0.5 P₄ and δG°(923) = 35.8 kcal for the reaction FeP_4,f + I₂ = FeI₂ + P₄.     

Der chemische Transport von Platin mit Chlor. Experimentell bearbeitet mit Marita Trenkel

The Chemical Transport of Platinum with Chlorine Experiments show that the chemical transport of platinum by means of chlorine within a temperature gradient at temperatures below ≈ 1000°K goes into the hot temperature region, but at higher temperatures in the reverse direction. From the thermodynamic discussion it can be seen, that the platinum content of the gas phase at low temperatures is governed by the exothermic formation of Pt₆Cl_12,g, and at higher temperatures by the endothermic formation of PtCl_3,g and PtCl_2,g. The platinum content of the gas phase passes a minimum at ≈ 1000°K, if P(Cl₂) = 3.5 atm. This result is in agreement with the observed inversion of the transport direction.     

Der chemische Transport von Kupfergermaniden und Kupfersiliciden

Chemical Vapor Transport of Intermetallic Systems. 9 Chemical Transport of Copper Germanides and Copper Silicides By means of chemical vapor transport using iodine and bromine as transport agents in the system Cu/Ge the compounds Cu₃Ge (ϵ and ϵ₁), Cu₅Ge (ζ) and copper‐rich mixed crystals Cu(Ge) have been prepared in form of single crystals. Thermodynamic considerations allow to understand the CVT process, especially the unexpected low temperatures. Copper silicides can be prepared under similiar conditions. They are extremely disordered. Their crystallographic characterisation was therefore impossible.     

Der chemische Transport der Phase CoS

The Chemical Transport of the CoS phase The CoS_x Phase can be deposited as single crystals by CTR using iodine, only if x is greater than 1.06. This is due to the sulphur phase equilibrium pressure which otherwise is too small for effecting this transport. HI or GeI₂ can be used as transport agent for specimens with less sulphur contents. Using GeI₂ CTR also yields monocrystals of the Co₉S₈ phase.     

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.     

Chemischer Transport intermetallischer Phasen. 4. Der chemische Transport von Co5Ge3 und CoGe

Chemical Vapor Transport of Intermetallic Systems. Chemical Transport of Co₅Ge₃ and CoGe By means of transport reaction (900 → 700°C, Iodine as transport agent) pure Co₅Ge₃ or Co₅Ge₃ with CoGe as a by-product can be prepared. Thermodynamic calculations allow to understand the reaction semiquantitatively.     

Der Chemische Transport von Sb2S3 mit J2

The Chemical Transport of Sb₂S₃ With I₂ The chemical transport of Sb₂S₃ with iodine is discussed on thermodynamical basis under consideration of the gaseous molecules I₂, I₁, SbI₃, S₂, S₃, S₄, S₅, S₆, S₇ and S₈. The experiments are in a satisfying agreement with the calculations.     

Chemischer Transport intermetallischer Phasen. 2 [1]. Der chemische Transport von Mischkristallen im System Co/Ni

Chemical Vapor Transport of Intermetallic Systems. 2. Chemical Transport of Co/Ni-mixed Crystals By means of chemical transport reaction it is possible to prepare Co/Ni-mixed crystals in a wide range of percentage composition between 5 and 75 weight % Nickel. This is possible using a 3-zone-oven. Thermodynamic considerations allow to understand the experiments.     

Der chemische Transport des Silbers mit Jod und die Umkehrung der Transportrichtung im Temperaturgefälle

The Chemical Transport of Silver with Iodine and the Inversion of the Transport Direction in the Temperature-Gradient The formation of Ag₃I_3,g from Ag_,s and I_,g is exothermic, the corresponding formation of AgI_,g is endothermic. Depending on the temperature one expects chemical transport of Ag into the higher or the lower temperature region. This inversion of the transport direction has been calculated thermodynamically and experimentally observed.     

Untersuchungen zur Kristallisation von Rhodium(III)-Oxoverbindungen unter Beteiligung der Gasphase – Der chemische Transport von Rh2O3 mit Chlor

Investigations on the Crystallization of Rhodium(III) Oxo Compounds – Chemical Vapour Transport of Rh₂O₃ using Chlorine Rh₂O_3,s migrates in chemical transport experiments with chlorine as transport agent from the higher (T₂) to the lower (T₁) temperature of a gradient (Δ_T = 100°) due to endothermal reactions (900°C < T ≤ 1050°C; T = 0,5 · (T₂ + T₁)). Under the conditions of transport experiments RhCl_3,s is observed in most experiments as equilibrium solid besides the sesquioxide. The transport rates for Rh₂O_3,s and the sublimation rates for RhCl_3,s grow with increasing temperature T . The composition of the equilibrium solids, the rates of migration and the sequence of deposition (1. RhCl_3,s, 2. Rh₂O_3,s) is well reproduced by thermodynamic model calculations. As a result of this calculations the transport behaviour of the system Rh₂O_3,s/Cl₂ is determined by the two equilibria The influence of RhCl_2,g and RhCl_4,g on the transport behaviour of Rh₂O_3,s as well as the possible occurence of RhOCl_2,g in the equilibrium gas phase will be discussed. Predictions of the transport behaviour of ternary rhodium(III) oxo compounds will be made.     

Chemischer Transport intermetallischer Phasen. 3 [1]. Der chemische Transport von Mischkristallen im System Mo/W

Chemical Vapor Transport of Intermetallic Systems. 3. Chemical Transport of Mo/W-mixed Crystals Mo/W-mixed crystals can be prepared by means of chemical vapor transport with HgBr₂ (1000°C→900°C). It is known [2] that the transport reaction of tungsten begins hours or even days after starting the experiment. This is the reason for the unusual composition of deposited crystals: EDX-analysis show them to have a Mo-rich nucleus and a W-rich shell.     

Das Massenspektrum des Systems Te/S und der chemische Transport von Tellur mit Schwefel

Mass Spectrum of the System Te/S and the Chemical Transport of Tellurium with Sulphur The mixed molecules TeS_x (x = 1 … 7) and Te₂S_y (y = 1 … 6) have been observed by mass spectrometry. These molecules are responsible for the fact, that Tellurium can be chemically transported by means of sulphur in a temperature gradient (375 → 325°C).     

Chemischer Transport intermetallischer Phasen. 5 [1]. Der chemische Transport von Ni3Sn und Ni3Sn2

Chemical Vapor Transport of Intermetallic Systems. 5. Chemical Transport of Ni₃Sn and Ni₃Sn₂ The congruent melting intermetallic compounds. Ni₃Sn and Ni₃Sn₂ can be prepared by CVT-methods using Iodine as transport agent. Thermodynamic calculations allow to understand why Ni₃Sn and Ni₃Sn₂ but not Ni₃Sn₄ can be prepared by this manner. Some general rules concerning CVT of intermetallics are given.     

Studien zum Chemischen Transport von Nickel mit Kohlenmonoxid im geschlossenen Reaktionsraum [1]

Studies on the Chemical Transport of Nickel with Carbon Monoxide in a Sealed Reaction Space The chemical transport of nickel by means of carbon monoxide (equation (1)) has been investigated experimentally in closed ampoules of a special shape. Besides the experiments the transport rate has been calculated approximately for different models assuming equilibrium between solid and gas motion by diffusion and stoichiometric flow. It is shown that the transport rate calculated in this way (with one exception) is between the limits given by calculation for diffusion only and neglecting the stoichiometric flow. The equilibrium pressures calculated with ΔH°₁(298) = ?35.0 kcal lead to transport rates which agree approximately with the rate determined experimentally (c. f. Table 4).     

Der Bestimmung von Hydroxylgruppen mit Grignard-Reagens

Ohne Zusammenfassung     

Elektrometrische Bestimmung von Nickel mit Silbernitrat

Ohne Zusammenfassung     

Die Bestimmung von Nickel mit der Atomfluorescenz-Flammen-Spektrometrie

Ohne Zusammenfassung