As a result of solid-state reactions three cadmium vanadates(V) have been obtained, i.e. CdV2O6, Cd2V2O7 and Cd4V2O9. Melting temperature and the product of melting has been determined for Cd4V2O9. Thermal properties of the obtained cadmium
vanadates(V) have been reinvestigated. The phase equilibria being established in the CdO-V2O5 system over the whole components concentration range up to the solidus line were described.
Authors:Agata Górniak, Alina Wojakowska, Stanisława Plińska, and E. Krzyżak
Electrical conductivity of solid systems AgX-MX2 (where M=Cd, Co, Zn and X=Cl, Br) were measured in a large range of temperature and compositions. Activation energies and conductivity values vs. composition are presented and discussed in relation to phase equilibria in the respective systems. Maximum of the conductivity
value and stabilization of the activation energy have been found for silver halides doped heavily with divalent cation e.g.
in the systems forming solid solutions on the silver halide side. Disorder in AgBr on the approach to melting, expected to
be higher than in AgCl, has been shown by means of original DSC curves presented for both halides.
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.
Authors:Alexandre Berche, Pierre Benigni, Jacques Rogez, and Marie-Christine Record
Literature results on the La–Mg binary system are critically reviewed. It is shown that most recent experimental results are not in agreement with the previously published assessments of the system. Thus, an experimental re-investigation of this phase diagram is required. Several alloys are synthesized from pure constitutive elements and characterized using X-ray diffraction, scanning electron microscopy, and differential thermal analysis. This study clarifies the phase equilibria in the La–Mg system. These results combined with the recent study of the enthalpies of formation of the intermediate compounds of this system provide a sound basis for the Calphad optimization of the system.
A set of phase diagrams for the systems CuX–AlkX
(where Alk=Li, Na, K, Rb or Cs and X=Cl, Br or I) is given, basing on authors investigation
and selected literature data. Sizes and valences of ions involved in Coulombic
and polarization interactions were considered as main factors affecting phase
equilibria. An increasing tendency for compound formation was noted in series
Na→K→Rb→Cs, Na→Li and I→Br→Cl. The most strongly
represented are compounds of the formulas AlkCu2X3
In this paper, examples are given of how calorimetric values can give greater certainty to phase equilibria calculated from
thermodynamic data. Errors that may arise when phase diagram evaluations are carried out largely from the basis of Gibbs energy
information only are illustrated by reference to recent evaluations of the Ti−Si system and the resulting calculated oxidation
behaviour of titanium silicides. The importance of calorimetric values for calculation of metastable phase equilibria is demonstrated
by results of work on the AlN−TiN hard-metal coating system. Finally, suggestions are made with regard to areas of work where
calorimetric data are urgently needed.
It has been demonstrated that Co2V2O7
and InVO4 react with each other forming a new compound
of the Co2InV3O11
formula, when their molar ratio is equal to 1:1, or among CoCO3,
In2O3 and V2O5,
mixed at a molar ratio of 4:1:3. This compound melts incongruently at the
temperature of 960±5°C, depositing crystals of InVO4.
It crystallizes in the triclinic system and the unit cell parameters amount
to: a=0.6524(6) nm, b=0.6885(5)
nm, c=1.0290(4) nm, α=96.5°, β=104.1°,
γ=100.9°, Z=2. The phase equilibria
being established in the Co2V2O7–InVO4
system over the whole components concentration range up to the solidus line
DTA and X-ray powder diffraction methods were used to study the phase equilibria established in the V9Mo6O40-FeVMoO7 system up to 1000° throughout the whole component concentration range. The experimental results are presented in the form of a phase diagram.
The phase equilibria in the Tl2Te-Bi2Te3 system were studied by means of cooling curve determination, differential thermal analysis and X-ray diffraction methods; the results obtained with the former two methods were compared. The phase diagram established for the system differed considerably from three others published previously.