The behaviour of Al2(MoO4)3 towards AIVO4 in the subsolidus area, over the whole component concentration range, has been studied using the DTA and XRD methods. The
experimental results have been presented in the form of a phase diagram. It has been found that components of the system of
interest do not remain in equilibrium, and AlVO4−Al2(MoO4)3 system is not a real two-component system, even in the subsolidus area.
The phase equilibria in the solid state in the system AlVO4−MoO3 were determined by DTA and XRD methods. The experimental results are presented in the form of a phase diagram. In the subsolidus
area, the system AlVO4−MoO3 is a real two-component system only within the range AlVO4−AlVMoO7.
Phase relations in
the solid state in the FeVO4–Co3V2O8
system, in the whole range of components concentration have been studied.
It was found that the composition of the phase of the howardevansite type
structure, formed in the investigated system, corresponds with the Co2.616Fe4.256V6O24 formula. The phase of the lyonsite type structure
has a homogeneity range with the Co3+1.5xFe4–xV6O24 formula (0.476 formula (0.476<x<1.667).
The melting temperature and the volume of the unit cell of the lyonsite type
structure phase increases together with the rise of cobalt quantity contained
in it. Basing on the results of the DTA and XRD measurements a phase diagram
of the FeVO4–Co3V2O8
system up to the solidus line was constructed.
A new compound Co3Fe4V6O24 has been obtained by solid state reaction. Temperature of its incongruent melting amounts to 8905C. Results of indexing
the powder diffraction pattern and unit cell parameters of Co3Fe4V6O24 are also given. This compound is probably isostructural with M3Fe4V6O24 (where M = Zn, Mg, Mn). IR spectrum of Co3Fe4V6O24 phase is presented.
Reactivity of FeVO4 towards Ni2V2O7 and Ni3V2O8 in the solid state was investigated. On the base of XRD and DTA results, phase diagrams in subsolidus area of the FeVO4-Ni2V2O7 and FeVO4-Ni3V2O8 intersections of the ternary system NiO-V2O5-Fe2O3 have been worked out and the phase diagram of this ternary system in subsolidus area in the whole component concentration
range has been verified.
Authors:Maria Kurzawa, Anna Blłońska-Tabero, and Izabella Rychłowska-Himmel
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.