The equilibrium phase diagram of the copper-indium system: a new investigation

The entire phase diagram of the Cu-In system was investigated using differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), metallography and electron probe microanalysis (EPMA) studies. The results indicate the existence of a solubility region of In in Cu with the limit of the solid solution at 5.20 at.% In at 400 °C and of six intermediate phases, the three low-temperature phases δ, η and Cu₁₁In₉, and the three high-temperature phases γ, η′ and β. The boundaries of each phase were defined with respect to temperature and composition.     

Thermodynamic study of sodium-iron oxides: Part II. Ternary phase diagram of the Na-Fe-O system

Studies on ternary phase diagrams of the Na-Fe-O system have been carried out from the thermodynamic point of view. Thermodynamic data of main ternary Na-Fe oxides Na₄FeO₃(s), Na₃FeO₃(s), Na₅FeO₄(s) and Na₈Fe₂O₇(s) have been assessed. A user database has been created by reviewing literature data together with recent DSC and vapor pressure measurements by the present authors. New ternary phase diagrams of the Na-Fe-O system have been constructed from room temperature to 1000 K. Stable conditions of the ternary oxides at 800 K were presented in predominance diagram as functions of oxygen pressure and sodium pressure.     

Thermodynamic and phase diagram investigation of Pb-BiIn section in Pb-Bi-In ternary system

The results of thermodynamic study of Pb-BiIn section of Pb-Bi-In system done experimentally by Oelsen calorimetry and calculated by general solution model, as well as measurements performed by DTA and optic microscopy in order to investigate phase diagram of the given section, are presented in this paper. Thermodynamic properties, such as integral molar enthalpies of mixing, activities, activity coefficients, partial and integral excess Gibbs energies at 600 and 650 K were determined and comparison between obtained experimental and calculated values were done. Also, based on cooling curves, DTA recordings and optic microscopy results phase diagram was constructed and compared with literature data.     

The phase diagram of the system poly(styrene-block-n-butyl methacrylate)

 The morphological phase diagram of poly(styrene-block-n-butyl methacrylate), P(S-b-n-BMA), has been investigated in detail using thermal analysis, microscopy, rheology and scattering techniques. The system shows an upper critical order transition as well as a lower critical order transition (LCOT). For the first time, morphologies of the ordered system at higher temperatures (LCOT) as well as of a block copolymer system frozen-in during the phase separation process are reported. The Flory–Huggins interaction parameter, χ depends not only on temperature, but also on the composition and the molecular weight of the block copolymers, resulting in an asymmetrical phase diagram. Furthermore, the deuteration of the PS block seems to increase the χ parameter of the P[(d ₈)S-b-n-BMA] system, reflecting the influence of small changes in architecture on phase behavior. The phase behavior and morphology of PS-b-PBMA are summarized in a phase diagram which is, however, quite complex and therefore needs further discussion. The equilibrium morphologies displayed are influenced by the temperature-dependent-conformation term as well as by the composition term. Received: 7 December 1999/Accepted: 28 April 2000     

The germanium-selenium phase diagram

The binary germanium—selenium system was investigated by differential thermal analysis; from the results a temperature-composition diagram was constructed. The existence of the two compounds GeSe and GeSe₂ was confirmed. Furthermore, it could be shown that between 920±4 and 939±2 K GeSe transforms to a high-temperature modification which is slightly richer in selenium and decomposes peritectically at 948±2 K. On the germanium-rich side of the system a monotectic equilibrium exists at 1 177±2 K. Two thermal effects, one between 908 and 918 K, the other one at 851±3 K, were shown to be non-equilibrium effects. GeSe and GeSe₂ form a eutectic at 856±2 K and 56.0±0.5 at% Se. The congruent melting point of GeSe₂ was determined as 1 015±2 K. Between GeSe₂ and Se another eutectic exists at 485±1 K and 94.5±0.5 at% Se.

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Das Germanium-Selen-Phasendiagramm

Zusammenfassung Das Zweistoffsystem Germanium—Selen wurde mit Hilfe der Differenz-Thermo-Analyse untersucht; aus den Ergebnissen wurde einT-x-Zustandsdiagramm erstellt. Die Existenz der zwei Verbindungen GeSe und GeSe₂ wurde bestätigt. Weiters konnte gezeigt werden, daß zwischen 920±4 und 939±2 K GeSe sich in eine Hochtemperatur-Modifikation umwandelt, welche etwas selenreicher ist und bei 948±2 K peritektisch zerfällt. Auf der germaniumreichen Seite des Systems existiert bei 1 177±2 K ein monotektisches Gleichgewicht. Von zwei thermischen Effekten, einem zwischen 908 und 918 K und einem anderen bei 851±3 K, konnte gezeigt werden, daß sie auf fehlendes Gleichgewicht zurückzuführen sind. GeSe und GeSe₂ bilden ein Eutektikum bei 856±2 K und 56,0±0,5 At% Se. Der kongruente Schmelzpunkt von GeSe₂ wurde zu 1 015±2 K bestimmt. Zwischen GeSe₂ und Se existiert ein weiteres Eutektikum bei 485±1 K und 94,5±0,5 At% Se.

     

A contribution to the ternary phase diagram Co-Sb-Te

The melting behaviour, some phase boundaries and the lattice parameters in the region of the NiAs-type phase in the ternary system cobalt-antimony-tellurium have been determined by differential thermal analysis and X-ray diffraction. A projection of the liquidus surface and the phase relationships in different sections with constant antimony/tellurium ratios are presented. The peculiar variation of the lattice parameters with the composition of the nonstoichiometric NiAs-type phase is discussed in terms of the defect structure.Dedicated to Prof. K. L. Komarek on the occasion of his 65th birthday     

Thermodynamic properties and phase equilibria of the lead-tellurium binary system

The liquidus curve of the Pb-Te binary was measured using two different DTA systems, one employing a small sample (0.2 g) and the second a large sample (5 g). An additional liquidus measurement method was employed for the Pb-rich region in which the liquid equilibrated with PbTe was analyzed chemically. The liquidus for the Pb-PbTe subsystem obtained is in agreement with several sets of data reported in the literature. The literature data for the PbTe-Te are in disagreement. Our measured values resolve this discrepancy and yield a eutectic temperature of 410.9±0.8°C at 89.1±0.3 at % Te. The system was thermochemically modelled using an associated solution model for the liquid phase and a defect model for PbTe. This model not only accounts for compositional and temperature dependences of the thermodynamic data but also for electron and hole concentrations within the homogeneous range of PbTe(c).On leave from India Institute of Technology-Kanpur, Kanpur, India.     

A ternary phase diagram of the Mn–Te–O system at 950 K

A ternary phase diagram of the Mn–Te–O system at 950 K has been established in the composition range in and around the MnO–TeO₂ pseudo binary line. Various preparation methods were employed to confirm the co-existence of different ternary phases. The results of these phase equilibration studies were revalidated by the invariancy of partial pressures at constant temperature during high temperature mass spectrometric vaporization experiments. The following three-phase regions have been identified: MnO+Mn₃O₄+Mn₆Te₅O₁₆ (phase region 1; PH1), Mn₃O₄+Mn₆Te₅O₁₆+MnTeO₃ (phase region 2; PH2), Mn₃O₄+MnTeO₃+Mn₃TeO₆ (phase region 3; PH3), and MnTeO₃+Mn₂Te₃O₈+Mn₃TeO₆ (phase region 4; PH4). The complex nature of the Mn–Te–O ternary system was revealed by the interesting results obtained by us with regard to preparation of samples and mass spectrometric vaporization experiments.     

Phase diagram of the hexamethylenetetramine: water system

Phase diagram of the hexamethylenetetramine–water system was studied with use of differential thermal analysis and powder X-ray diffraction methods. The only polyhydrate, with the composition (CH₂)₆N₄·6H₂O (m.p. = 12.9 °C), was found. New experimental data on the solubility of (CH₂)₆N₄ in water were obtained by different methods that show decreasing the (CH₂)₆N₄ solubility with increasing temperature.     

Nitrous oxide: Saturation properties and the phase diagram

The experimental values of the coordinates of the triple point and of the critical point of nitrous oxide registered in the literature were assessed and those judged as most reliable have been selected. Empirical equations have been found for the vapour pressure, sublimation and fusion curves. The virial coefficients and saturation properties as functions of temperature along the equilibrium curves are described by reduced equations. They were used in arriving at the molar enthalpies at the triple point and the normal boiling temperature. Equations for the sublimation and fusion curves resulting from the exactly integrated Clapeyron equation compare favourably with the results from the empirical treatment and the experimental data.     

Conductivity, calorimetry and phase diagram of the NaHSO4–KHSO4 system

Physico-chemical properties of the binary system NaHSO₄–KHSO₄ were studied by calorimetry and conductivity. The enthalpy of mixing has been measured at 505 K in the full composition range and the phase diagram calculated. The phase diagram has also been constructed from phase transition temperatures obtained by conductivity for 10 different compositions and by differential thermal analysis. The phase diagram is of the simple eutectic type, where the eutectic is found to have the composition X(KHSO₄) = 0.44 (melting point ≈ 406 K). The conductivities in the liquid region have been fitted to polynomials of the form κ(X) = A(X) + B(X)(T − T_m) + C(X)(T − T_m)², where T_m is the intermediate temperature of the measured temperature range and X, the mole fraction of KHSO₄. The possible role of this binary system as a catalyst solvent is also discussed.     

Phase diagram of the ternary system NMMO/water/cellulose

The phase diagram of the system N-methylmorpholine-N-oxide(NMMO)/H₂O/cellulose has been measured at 80 °C by establishing a solubility map (observation of the mixtures under the microscope), by the analysis of coexisting phases and determining the critical point. These experiments manifest a continuous reduction of the two phase area existing for the subsystem H₂O/cellulose upon the addition of NMMO, where a weight fraction of NMMO in the mixed solvent exceeding 75 wt% is required for Solucell 400 to reach the critical composition. The critical cellulose concentration is only 0.34 wt%, i.e., more than an order of magnitude lower than for the solutions of typical vinyl polymers in mixed solvents. All experimental observations can be well modeled on the basis of composition dependent binary interaction parameters by means of recently established mixing rules. For the subsystems H₂O/cellulose and NMMO/water the corresponding data are known from independent earlier measurements. The adjustment of two parameters to the ternary phase diagram was required to obtain this information for NMMO/cellulose, the third binary subsystem.     

Density and phase diagram of the magnesium–lead system in the region of Mg2Pb intermetallic compound

The phase diagram of magnesium–lead system has been investigated by a new method for phase analysis on the basis of a strong penetrating radiation. The measurements have shown that the standard phase diagram of this system contains inaccuracy in the region of the Mg₂Pb intermetallic compound. New data on the temperature dependences of the solid and the melt densities have been obtained. The density change during the phase transitions has been directly measured.     

Solid solutions of perovskite in the LaO1.5-BaO-ScO1.5-ZrO2 system at 1600 °C

A partial pseudoternary phase diagram of the LaO_1.5-BaO-ScO_1.5 system was established at 1600 °C. According to the phase diagram, the solubility of barium into the cubic perovskite phase (LaScO₃) at 1600 °C is 0.24 in a mole fraction of barium oxide (X_BaO) on the composition line where the mole fraction of scandium oxide is 0.50. Another cubic perovskite phase (BaZrO₃) in the BaO-ZrO₂-ScO_1.5 system is also known. We investigated the phase relationships between the two cubic perovskites in the pseudoquaternary phase diagram of the LaO_1.5-BaO-ScO_1.5-ZrO₂ system. As a result, we found the existence of a wide solid solution region between the cubic perovskites at 1600 °C. The region was determined by X-ray diffraction (XRD) analysis and energy dispersive X-ray (EDX) microanalysis of samples with various compositions, and established the partial pseudoquaternary phase diagram.     

Prediction of formation of cubic boron nitride by construction of temperature-pressure phase diagram at the nanoscale

The size-dependent phase diagram of BN was developed on the basis of the nanothermodynamic theory. Our studied results suggest that cubic BN (c-BN) is more stable than hexagonal BN (h-BN) in the deep nanometer scale and the triple point of c-BN, h-BN and liquid shifts toward the lower temperature and pressure with decreasing the crystal size. Moreover, surface stress, which is determined by the experimental conditions, is the main reason to influence the formation of c-BN nuclei. The developed phase diagram of BN could help us to exploit new techniques for the fabrication of c-BN nanomaterials.     

Correlation between macrovoid formation and the ternary phase diagram for polyethersulfone membranes prepared from two nearly similar solvents

The morphological structure of membranes prepared from two nearly similar systems consisting of water/N,N-dimethylacetamide (DMAc)/polyethersulfone (PES) and water/N-methyl-2-pyrrolidone (NMP)/polyethersulfone (PES) has been studied. The morphology of the prepared membranes showed that both systems exhibit an instantaneous liquid–liquid demixing that leads to the formation of macrovoids in the resulting structures. Nevertheless, the resulting macrovoid structures were contrary to the generally accepted concepts concerning macrovoid formation. The membranes morphologies showed that in spite of better miscibility between water and DMAc, which must promote the formation of channel- and finger-like structures, more sponge-like structures were observed in membranes prepared from the water/DMAc/PES system compared to those prepared from the water/NMP/PES system. To find the source of this unexpected phenomenon, the complete ternary phase diagrams consisting of theoretical binodal curves, vitrification boundaries, and gelation boundaries were constructed for both systems and it was shown that gelation process occurs earlier in the water/DMAc/PES system compared to the other system, which inhibits the growth of macrovoids in this system.     

Phase transformations and phase diagram at equilibrium in the Cu-Ni-Sn system

The Cu-Ni-Sn ternary phase diagram in the Cu rich side has not been experimentally determined or calculated at low temperatures. Two Cu9NixSn alloys with x=2 and 6 mass% Sn were studied. The precipitation sequence during the ageing and phases responsible for the strengthening were determined.     

High temperature phase transition of mixed (PuO2 + ThO2) investigated by laser melting

A laser heating approach combined with fast pyrometry in a thermal arrest method was used to provide new data for the melting/solidification phase transition in mixed (PuO₂ + ThO₂) at high temperature. At low concentration of ThO₂ in PuO₂ a minimum in the solidification temperature in the pseudo binary (PuO₂ + ThO₂) was observed. The minimum was found around a composition with 5 mol% ThO₂. Phase transition temperatures of other compositions are closer to an ideal solution behaviour. To detect changes in the material a complete investigation with electron microscopy, Raman spectroscopy and powder X-ray diffraction was done. Raman vibration modes were found, that are characteristic for materials containing PuO₂, and high temperature segregation effects during solidification were described. The results obtained in the present work are compared to other mixed actinide dioxides and compared to the ideal solution case for this system. The presented results show the importance of the high-temperature oxygen chemistry in this actinide oxide phase.     

Contribution to phase diagram investigation of Pb-In binary system

Experimental results obtained by phase diagram investigation of Pb-In binary system are presented in the paper and compared with literature data. Liquidus and solidus temperatures, as well as cell parameters were determined, and structural analysis of this system was made. Microstructural analysis was done by SEM-EDX, crystallographic analysis was performed by diffractometry, while liquidus and solidus temperatures were determined by DTA. Obtained results show that in investigated system exist three areas: area reach in In, area reach in Pb and separating the intermediate phase (αIn). Experimental results show good agreement with literature. This revised version was published online in July 2006 with corrections to the Cover Date.