Authors:M. Boča, V. Danielik, Z. Ivanová, E. Mikšíková, and B. Kubíková
The phase diagrams of the systems KF-K2TaF7 and KF-Ta2O5 were determined using the thermal analysis method. The phase diagrams were described by suitable thermodynamic model. In
the system KF-K2TaF7 eutectic points at xKF=0.716 and t=725.4°C and at xKF=0.214 and t=712.2°C has been calculated. It was suggested that K2TaF7 melts incongruently at around 743°C forming two immiscible liquids. The system KF-Ta2O5 have been measured up to 8 mol% of Ta2O5. The eutectic point was estimated to be at xKF∼0.9 and t∼816°C. The formation of KTaO3 and K3TaO2F4 compounds has been observed in the solidified samples.
To study the coherence of thermodynamic data of the AgNO3-LiNO3 -RbNO3 ternary system, phase diagram of the binary system AgNO3 -LiNO3 has been obtained between 303 and 550 K by direct and differential thermal analysis technique. This system is characterized
by an eutectic point (25% mol. LiNO3 , 445±1 K) and a plateau due to the solid-solid transition in AgNO3 at 434±1 K. In the solid state the solubility of each component in the other seems to be nil or negligible (no more than
a few percents). Using other thermodynamic data, the excess properties of the binary liquid (AgNO3 - LiNO3 ) were calculated at 623 K.
Competing groups in a population will be integrated or segregated depending on their contest strategies.
In this work a population of a fixed proportion of hawks and doves is supposed to be able to employ two different contest
strategies, one more competitive than the other one. Energies are derived for populations employing these strategies and these
energies depend on the availability of the resource for which hawks and doves compete.
The energy for the less competitive strategy is lower than the other one when the resource is abundant. In that case hawks
and doves can be in cohabitation in all proportions. If, however, the resource is scarce, the energy of the more competitive
strategy is lower than the other one. In that case complete segregation of hawks and doves into colonies will result.
The situation is akin to the phase pressure diagram of a binary solution with eutectic point, miscibility gap in the liquid
phase and complete miscibility in the vapour phase.
Thermal analysis of the binary system KCl-LiCl in the composition range 0.368–0.812 mol fraction of LiCl was studied by differential
scanning calorimetry (DSC). On the basis of the DSC curves, the experimental data for the phase-diagram, the latent heat of
fusion, and the average specific heat in the liquid and solid states are presented as a function of the composition of the
mixture. The experimental results compared with literature data. The following empirical correlation between the heat of fusion
(ΔH) and of compositions of the mixture in mol fraction of LiCl (x) was obtained: ·GH=26.95−50.20x+43.06x2 with a minimum value of 11.8 kJ(g mol)−1 at the eutectic point of 0.587 mol fraction of LiCl at 354.4°C. These results are required as basic data to develop thermal
energy storage materials, based on the phase change of a molten mixture of KCl-LiCI.
It is well-known that eutectics do not necessarily grow at the eutectic temperature, or with the eutectic composition. Thus,
the eutectic point can be shifted due to nonequilibrium conditions in the system. This fact was observed in many experiments.
We try to explain this behaviour on base of the study of phase transformation kinetics. We construct the kinetic phase diagrams
of PbCl2−AgCl within the framework as of the nucleation theory as of the theory of growth on the phase interface. Our models are based
on the molecular model of the difference of chemical potential of components for the liquid and solid phases. The proposed
model describes the position of the eutectic point very well and is practically applied for the study of nonequilibrium directional
growth in the PbCl2−AgCl system.
The phase diagram of the SnI2-CuI system was determined by the method of thermal analysis. No intermediates were found. It is suggested that limiting solid solutions of SnI2 inγ-CuI,β-CuI andα-CuI, respectively, are formed. The eutectic point parameters (32.7 mol% CuI, 270.4 ±0.1 °C) and those of two invariant points (64.0 mol% CuI, 385.3 ±0.5 °C and 61.5 mol% CuI, 366.6±0.2 °C), corresponding to the equilibriaα+liquid ⇄β andβ+liquid ⇄γ, respectively, were determined.
After studying the thermal behaviour of the reactants the authors have established the diagrams of state of binary systems of aminophenazone form (I) with phenazone and with amino-4-phenazone by thermomicroscopy, differential scanning calorimetry and differential thermal analysis. Only one eutectic point is observed for each binary system, the fusion temperature and the composition of which have been determined.
Authors:Zuzana Netriová, M. Boča, V. Danielik, and Eva Mikšíková
The phase diagrams of the binary system Ta2O5-K2TaF7 and the ternary system KF-Ta2O5-K2TaF7 were determined using the thermal analysis method. The system Ta2O5-K2TaF7 was measured up to 25 mol% of Ta2O5. Eutectic point is estimated to be at
=0.14 and t=601°C. Crystallization of K2TaF7, K2Ta2O3F6 and a new phase was identified. The new phase shows isomorphism with K3Nb2F11O. In the ternary system four nonvariant equilibria points at 3 mol% of Ta2O5, 72 mol% of KF and 25 mol% of K2TaF7 at 715(1)°C; 6 mol% of Ta2O5, 44 mol% of KF and 50 mol% of K2TaF7 at 603(2)°C; 1 mol% of Ta2O5, 22 mol% of KF and 77 mol% of K2TaF7 at 704(1)°C and 8 mol% of Ta2O5, 8 mol% of KF and 84 mol% of K2TaF7 at 580(1)°C were proposed. Crystallization fields of KF, K2TaF7, K3TaF8, K3TaOF6, K4Ta2OF12 and K2Ta2O3F6 were considered.
Authors:B. L. Sharma, Parshotam Lal, Monika Sharma, and Arun K. Sharma
.03458 0.1302 0.317 −0.925 −0.553 150.7 145.81 0.9 349 0.02566 0.2157 0.57 −1.636 −0.964 174 377.79 The values of G E and S E at eutecticpoint, e * by Guggenheim lattice theory, are −1.40 kJ mol −1 and 4.50 J mol −1 K −1 , respectively Table 7
invariant point. At the eutecticpoint, just below the eutectic temperature, both components separate out from the liquid phase of eutectic composition to two solid phases.
Phase diagram of benzoin and