Re-investigation of the La–Mg phase diagram

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.     

Pressure–temperature phase diagram of SeO2. Characterization of new phases

We have investigated SeO₂ at high pressures and high temperatures. Two new phases (β-SeO₂ and γ-SeO₂) and the boundary separating them have been found, following experimental runs performed at pressures up to 15 GPa and temperatures up to 820°C. The two phases crystallize in the orthorhombic system in space group Pmc2₁ (no. 26) with a=5.0722(1) Å, b=4.4704(1) Å, c=7.5309(2) Å, V=170.760(9) Å³ and Z=4 for the β-phase, and with a=5.0710(2) Å, b=4.4832(2) Å, c=14.9672(6) Å, V=340.27(3) Å³ and Z=8 for the γ-phase. Both phases are stable at ambient pressure and temperature below −30°C. At ambient temperature the phases return to the starting phase (α-SeO₂) in a few days. We discuss our findings in relation to a previous report of in-situ measurements at high pressures and ambient temperature.     

Study and 3D modeling of the phase diagram of the Ag–Ge–Se system

In view of the contradictoriness of the literature data, phase equilibria in the Ag–Ge–Se system were restudied by differential thermal analysis and X-ray powder diffraction analysis. A number of polythermal sections and an isothermal section at room temperature of the phase diagram were constructed, and so was the projection of the liquidus surface. The primary crystallization fields of phases and the types and coordinates of in- and monovariant equilibria were determined. It was shown that, in the system, a single ternary compound, Ag₈GeSe₆, forms, which undergoes congruent melting at 1175 K and a polymorphic transformation at 321 K. The formation of the compounds Ag₂GeSe₃ and Ag₈GeSe₅, which was previously reported in the literature, was not confirmed. Based on the phase diagrams of boundary binary systems and the results of the differential thermal analysis of a number of samples of the ternary system, equations were obtained for calculation and 3D modeling of the liquidus and phase-separation surfaces.     

Experimental investigation and thermodynamic prediction of the Al–Ge–Zn phase diagram

The knowledge of the phase diagram of the Al?CGe?CZn ternary system is of importance in the development of high temperature soldering materials. In this study, the phase diagram of the Al?CGe?CZn ternary system was calculated by the calculation of phase diagrams method using binary thermodynamic parameters included in the COST MP0602 thermodynamic database. Chosen alloys with compositions along two vertical sections with molar ratio Al/Ge?=?3/1 and 1/3 were measured using DTA (differential thermal analysis). The experimentally determined phase transition temperatures from this work and phase equilibria data from literature were compared with calculation results and good mutual agreement was noticed.     

The phase diagram of KNO3–RbNO3

The phase diagram of the binary system KNO₃–RbNO₃ was studied using simultaneous direct and differential thermal analysis technique and differential scanning calorimetry. This system exhibits six invariants: a eutectic at 293 °C, four eutectoïd reactions at 109, 157, 159, and 291 °C, respectively, and a peritectoïd one at 288 °C.     

The Nb-rich part of the NbGa phase diagram

Ten alloys in the composition range 11–40 at.% Ga were produced by a four-stage process that involved both sintering and melting stages. These alloys were heat-treated at temperatures in the range 700–1600 °C until equilibrium was attained. The phases present after heat treatment were studied by means of X-ray diffraction, electron probe microanalysis and light microscopy. From the data obtained, the temperature dependence of the solubility limit of gallium in niobium was determined, the homogeneity range of Nb₃Ga was defined, and the second most niobium-rich compound was identified as oxygen-stabilised Nb₅Ga₃O_x.     

The phase diagram of the Ga–S system in the concentration range of 48.0–60.7 mol% S

Journal of Thermal Analysis and Calorimetry - A novel flame-retarded epoxy resins system is prepared by copolymerizing diglycidyl ether of bisphenol A (EP) with tris(3-nitrophenyl) phosphine...     

Thermodynamic assessment of phase diagram and concentration–temperature dependences of properties of solid solutions of the GaS–GaSe system

Journal of Thermal Analysis and Calorimetry - Before 100,000 years ago, during the Middle Stone Age (MSA) of South Africa, silica varieties of minerals and rocks were sometimes heated...     

Phase diagram of the Sn–P system

Journal of Thermal Analysis and Calorimetry - The T–x diagram of the Sn–P system was studied by differential thermal analysis, X-ray phase analysis and local X-ray spectral...     

The section of the Fe–Ni–S phase diagram constructed by directional crystallization and thermal analysis

A nontrivial polythermal cross-section through the Fe–Ni–S phase diagram was plotted using a combination of directional crystallization and DTA methods. The crystallized sample was grown from the liquid (L) of the following composition Fe = 18, Ni = 35, and S = 47 at.%. It consisted of two single-phase sites formed from mss (Fe _z Ni_1?z )S_1±δ and hzss (Ni _z Fe_1?z )_3±δS₂. The phase reaction L + mss = hzss proceeded on the boundary between these sites. The trajectories of melt and solid composition on the Gibbs triangle were calculated from the distribution of components along the sample. The tie-line transformation was determined from these data. Liquidus temperatures along the trajectory were measured by the DTA method and calculated with the help of a mathematical model. The nontrivial cross-section of the diagram constructed from these data shows the phase equilibrium conditions. The cross-section consists of two tie-line linear surfaces L–mss and L–hzss.     

Study of the polythermal diagram water–sodium sulphate–piperidine

Two isothermal sections of the isobaric ternary system H₂O–Na₂SO₄–C₅H₁₀NH were determined by isoplethic thermal analysis at 293 and 323 K. The compositions of the aqueous and organic invariant liquids, respectively L1 and L2, as well as that of the critical point, were characterized for each isotherm. The temperature of the invariant reaction was obtained by controlled flow thermal analysis and the temperature of the demixing ending, by interpolation of the monovariant lines. All these informations allowed us to establish the isobaric polythermal diagram of the H₂O–Na₂SO₄–C₅H₁₀NH system, for the temperature range 293–323 K, as well as a qualitative representation of the monovariant curves. This system is then characterized by a wide miscibility gap, three crystallization domains, and four-three-phase invariant domains. The relevant exploitation of this diagram so permits us to deduce the demixing temperature leading to the optimal transfer of the organic compounds in the light phase and also the composition of the organic phase recovered after this first step of extraction.     

A study on the phase diagram of AlF3CsF system

Phase relations of the AlF₃CsF system have been investigated by the methods of DTA and XRD with quenching technique. Four compounds were identified: Cs₃AlF₆, CsAlF₄, CsF·2AlF₃ and CsF·3AlF₃. Cs₃AlF₆ melts congruently at 790°C. The first eutectic, E₁, between Cs₃AlF₆ and CsF is located in 10.0 mol% AlF₃ at 654°C. CsF·2AlF₃ and CsF·3AlF₃ melt incongruently at 508° and 653°C, respectively. The second eutectic, E₂, was observed in 42.0 mol% AlF₃ at 471°C. The compound CsAlF₄ formed in the solid eutectic when cooled below 443°C. CsAlF₄ has α and β forms, transformation of which takes place reversibly at 422°C. All phase structures in the system were confirmed by X-ray powder diffraction analysis.     

The polythermal section of the Cu–Fe–Ni–S phase diagram constructed using directional crystallization and thermal analysis

The polythermal section of the Cu–Fe–Ni–S liquid–solid diagram in a field of equilibrium between sulfide melt L and monosulfide solid solution has been constructed using the quazi-equilibrium directional crystallization of melt Cu = 10.0, Fe = 38.5, Ni = 2.5, S = 49.0 mol% and DTA. The curves of distribution of Ni, Fe, Cu, and S in the sample were constructed. These data were used for determining the crystallization path in concentration tetrahedron and for calculating the distribution coefficients of components between solid and liquid solutions. To plot the liquidus line with the help of the DTA method, we determined the melting points of specially synthesized samples.     

Electrodeposition and electrochemical properties of novel ternary tin–cobalt–phosphorus alloy electrodes for lithium-ion batteries

Porous Sn–Co–P alloy with reticular structure were prepared by electroplating using copper foam as current collector. The structure and electrochemical performance of the electroplated porous Sn–Co–P alloy electrodes were investigated in detail. Experimental results illustrated that the porous Sn–Co–P alloy consists of mainly SnP_0.94 phase with a minor quantity of Sn and Co₃Sn₂. Galvanostatic charge–discharge tests of porous Sn–Co–P alloy electrodes confirmed its excellent performances: at 50th charge–discharge cycle, the discharge specific capacity is 503 mAh g^?1 and the columbic efficiency is as high as 99%. It has revealed that the porous and multi-phase composite structure of the alloy can restrain the pulverization of electrode in charge/discharge cycles, and accommodate partly the volume expansion and phase transition, resulting in good cycleability of the electrode.     

Simple modification of the temperature dependence of the Sanchez–Lacombe equation of state

In this work, the interaction energy term of the Sanchez–Lacombe equation of state (SL EOS) was modified to take into account the temperature dependence of hydrogen bonding and ionic interactions. A simple function was used in the form of the Langmuir equation that reduces to the original SL EOS at high temperature. Comparisons are shown between the ?*-modified SL EOS and the original SL EOS. The ?*-modified SL EOS could represent volumetric data for the group of non-polar fluids, polar fluids and ionic liquids to within an absolute average deviation (AAD) of 0.85%, 0.51%, and 0.054%, respectively whereas, the original Sanchez–Lacombe EOS gave AAD values of 0.99%, 1.2%, and 0.21%, respectively. The ?*-modified SL EOS provides remarkably better PVT representation and can be readily applied to mixtures.