I. Rychlowska-Himmel

Reinvestigation of Phase Equilibria in the V2O5–ZnO System

A diagram of phase equilibria established in a two-component oxide system V25–ZnO has been worked out applying differential thermal analysis and X-ray phase analysis as well as depending on investigations carried out with the aid of high-temperature X-ray attachment and scanning electron microscope linked to an X-ray microanalyser.

Reactivity of FeVO4 towards oxides and pyrovanadates(V) of Co and Ni

Abstract A novel Co 2 FeV 3 O 11 compound was obtained from a solid state reaction. Co 2 FeV 3 O 11 undergoes a reversible polymorph transition at 770 ± 5°C. It melts congruently at 980 ± 5°C. The indexing results and the calculated unit cell parameters for both polymorphs of Co 2 FeV 3 O 11 as well as for the previously obtained Ni 2 FeV 3 O 11 and Ni 2 FeVO 6 compounds are given. The IR spectra of the above-mentioned compounds are presented.

Neutron diffraction study of Mg2FeV3O11-δ

The neutron diffraction patterns of Mg2FeV3O11-δ compound at various low temperatures have been investigated. No magnetic ordering was observed in the investigated temperature range down to 10K. These materials have been formed in the triclinic space group but there are specific differences in the positions of atoms as compared to previously determined from XRD method. The iron(III) ions are distributed non-statistically with magnesium(II) ions and this could be responsible for some differences in the structure of the above sample. The method of sample preparation, in particularly thermal annealing processes could be responsible for the differences.

Phase equilibria in the systems Fe2O3-WO3 and FeVO4-WO3

Abstract Diagrams of phase equilibria of the systems Fe 2 O 3 -WO 3 and FeVO 4 -WO 3 have been constructed based on the results of DTA and X-ray phase powder diffraction. It was found that Fe 2 WO 6 melts incongruently at 1100 ± 10°C yielding solid α-Fe 2 O 3 , and that the FeVO 4 -WO 3 system is not a two-component system, even below the solidus line.

Studies on the System ZnO-V2O5-Fe2O3 Reactivity of ZnFe2O4 Towards ZnV2O6

Studies on the reactivity of ZnFe2O4 towards ZnV2O6 revealed that in the solid state the phases interact in a molar ratio of 1:3 to form a new compound, to which the molecular formula Zn2FeV3O11 was assigned. The compound melts congruently at 825±5°C.

Phase diagram of the FeVO4Fe2WO6 system

Abstract A diagram for the phase equilibria established in the two-component FeVO 4 Fe 2 WO 6 system has been constructed from measurements made by DTA and X-ray phase analysis. The diagram shows that the system investigated does not appear as a real two-component system, not even below the solidus line, and that its components form a eutectic mixture with a melting temperature of 810 ± 5°C (at a 15.00 mol% content of Fe 2 WO 6 ).

Phase relations in subsolidus area of ZnO-V2O5-Fe2O3 system

Phase equilibria in subsolidus area in the ZnO-V2O5-Fe2O3 system have been investigated over the whole concentration range of the oxides. The components of this system form two compounds: Zn2FeV3O11 and Zn3Fe4(VO4)6. A solidus area projection onto the component concentration triangle plane of the ZnO-V2O5-Fe2O3 system has been constructed using DTA and XRD methods. 11 subsidiary subsystems can be distinguished in this system. Melting temperatures of mixtures of solid phases coexisting at equilibrium in each of subsidiary subsystems were determined.

Phase Equilibria in the System Fe2O3–V2O5 –WO3 in the Solid State

The DTA and X-ray powder diffraction imply the following equilibria in the system FeVO4-WO3 up to the solidus line: from 550 to 650–670°C, the system components remain inert towards each other in the whole concentration range; above 670°C, at up to 66.67 mol% of WO3. FeVO4 and FeVW2O10 are in equilibrium, whereas from 66.67 mol% of WO3 upwards FeVW2O10 and WO3 are in equilibrium.ZusammenfassungDTA Untersuchungen und Debye-Scherrer-Aufnahmen lassen darauf schließen, daß im System FeVO4-WO3 bis zur Soliduslinie folgende Gleichgewichte festgestellt wurden: von 550 bis 650–670°C bleiben die Systemkomponenten im ganzen Konzentrationsbereich voneinander unberührt, oberhalb 670°C sind bis zu 66.67 Molprozent WO3 die Verbindungen FeVO4 und FeVW2O10 im Gleichgewicht vorhanden, oberhalb 66.67 Molprozent WO3 hingegen die Verbindungen FeVW2O10 und WO3.

Phase Equilibria in the System V2O5–Fe8V10W16O85 and Some Properties of the Fe8V10W16O85 Phase

A phase diagram of the V2O5–Fe8V10W16O85 system were carried out using XRD and DTA methods. In addition, an indexing of Fe8V10W16O85 powder diffraction pattern was made and its basic crystallographic parameters were determined. Finally, the phase was studied using IR spectroscopy.

A search for new phases in the system Fe2O3-V2O5-WO3

Studies on the three-component system Fe2O3-V2O5-WO3 have shown the occurrence of a new, compound with molecular formula FeVW2O10. Its X-ray characteristics and its melting temperature, 865±10 °C, have been established.ZusammenfassungEinleitende Untersuchungen am Dreikomponentensystem Fe2O3-V2 O5-WO3 zeigten das Auftreten einer neuen, noch nicht publizierten Verbindung der Formel FeVW2O10. Die Verbindung wurde röntgenographisch beschrieben, ihr Schmelzpunkt beträgt 865 ±10°C.