Phase relations and ordering in the dysprosia-zirconia system

The phase diagram in the subsolidus for the system Dy₂O₃-ZrO₂ has been established. The areas of existence of the high temperature solid solutions based on ZrO₂ and Dy₂O₃ were determined using the precision lattice parameter method. At low temperature, long-range ordering occured in the Dy₂O₃-rich region (>50 mol% Dy₂O₃) and two hexagonal compounds of an M₇O_11.5- and M₇O₁₁-type were found. The first of these compounds is formed at about 55 mol% Dy₂O₃ and possesses a very narrow homogeneity range. At approximately 1750° C this compound undergoes a transformation into cubic solid solutions of fluorite and C-type. The second is formed within the Dy₂O₃ concentration range between ~65 and 90 mol% Dy₂O₃. Above 1700° C the hexagonal compound Dy₆ZrO₁₁ undergoes a transformation into a cubic solid solution of C-type.     

Phase relations in the ternary system Cu-In-Se

The phase relations of the ternary system Cu-In-Se were studied at 750° C by quenching experiments. Special attention was given to the region CuInSe₂In₂Se₃-In₄Se₃. Only four ternary phases with extended homogeneity ranges were found to exist. They were characterized by X-ray powder diffraction, electron microprobe analysis (EK8PA)' end optical microscopy. Differential thermal analysis (DTA) investigations allowed us to construct theT-x diagram of the Cu₂Se-In₂Se₃. out between 47 and 100 mol% In₂Se₃. Besides, it was also possible to give a tentative diagram of the solid-liquid equilibria at 750° C and to get some information on the sub-solid existence fields beside the Cu₂Se-In₂Se₃ cut.     

Phase relations in the ternary Cu-Ga-In system

The phase relations of the Cu-Ga-In system were investigated in a composition range which is relevant for the production of Cu(In,Ga)Se₂ based thin film solar cells. The alloys Cu₁₆(In_{1 − y}Ga_y)₉, Cu₉(Ga,In)₄ and elemental In could be identified as the equilibrium phases of a ternary subsystem in the Cu-Ga-In phase diagram. The coexisting phases are well developed until 220 °C. In the case of Cu₉Ga₄ it is remarkable that the solubility of In in Cu₉Ga₄ highly increases with increasing temperature. Consequences for the selenization of metallic Cu-In-Ga precursors are discussed.     

Phase relations and hydrogen absorption of neodymium-iron-(boron) alloys

Based on an investigation of the phase correlations in the system Nd-Fe-B, a complete study of the hydrogen absorption of Nd-Fe-B alloys is presented, mainly concerning the permanent magnet material Nd₂Fe₁₄ B. Absorption isotherms of the compound Nd₂Fe₁₄ B and of the master alloy for permanent magnet production, Nd₁₅Fe₇₇B₈, have been recorded and their hydrogenation behaviour is discussed. Thermal desorption spectra support the conclusion that neodymium hydride is the second hydride phase in the hydrogenated master alloy. In the Nd-Fe binary system, Nd₂Fe₁₇ was confirmed as the only equilibrium phase at 870 and 1170 K. The properties of a new ferromagnetic ternary hydride Nd₂Fe₁₇H_x,x = 0 to 5, with the Th₂Zn₁₇ type structure, space group , are reported.     

Phase relations in the system Cu-La-O and thermodynamic properties of CuLaO2 and CuLa2O4

Phase relations in the system Cu-La-O at 1200 K have been determined by equilibrating samples of different average composition at 1200 K, and phase analysis of quenched samples using optical microscopy, XRD, SEM and EDX. The equilibration experiments were conducted in evacuated ampoules, and under flowing inert gas and pure oxygen. There is only one stable binary oxide La₂O₃ along the binary La-O, and two oxides Cu₂O and CuO along the binary Cu-O. The Cu-La alloys were found to be in equilibrium with La₂O₃. Two ternary oxides CuLaO₂ and CuLa₂O₄₊ were found to be stable. The value of varies from close to zero at the dissociation partial pressure of oxygen to 0.12 at 0.1 MPa. The ternary oxide CuLaO₂, with copper in monovalent state, coexisted with Cu, Cu₂O, La₂O₃, and/or CuLa₂O₄₊ in different phase fields. The compound CuLa₂O₄₊, with copper in divalent state, equilibrated with Cu₂O, CuO, CuLaO₂, La₂O₃, and/or O₂ gas under different conditions at 1200 K. Thermodynamic properties of the ternary oxides were determined using three solid-state cells based on yttria-stabilized zirconia as the electrolyte in the temperature range from 875 K to 1250 K. The cells essentially measure the oxygen chemical potential in the three-phase fields, Cu + La₂O₃ + CuLaO₂, Cu₂O + CuLaO₂ + CuLa₂O₄ and La₂O₃ + CuLaO₂ + CuLa₂O₄. Although measurements on two cells were sufficient for deriving thermodynamic properties of the two ternary oxides, the third cell was used for independent verification of the derived data. The Gibbs energy of formation of the ternary oxides from their component binary oxides can be represented as a function of temperature by the equations:

Phase relations in the MoO3-MgMoO4 system

Journal of Materials Science Letters -     

Phase relations in the BiI3-ZnI2 system

The liquidus diagram of the BiI₃-ZnI₂ system has been studied for the first time by differential thermal analysis, x-ray diffraction, and optical microscopy. The crystallization temperatures and melt compositions corresponding to eutectic and transition points have been determined, and a compound of composition ZnBiI₅, melting congruently at 400°C, has been identified. Some of its physicochemical properties have been studied.     

Phase relations and crystallization of glass in the system PbO-GeO2

Thermal properties and chemical compositions of glasses suitable for crystallization of ferro-electric Pb₅Ge₃O₁₁ are described. The crystallization of lead germanate glass was investigated by DTA and X-ray diffraction. In the range from 62 to 62.5 of PbO in mole per cent, Pb₅Ge₃O₁₁ was obtained as a single phase after a heat treatment. In the chemical composition around 5PbO·3GeO₂ in the binary system of PbO-GeO₂, Pb₅Ge₃O₁₁ and two new phases of Pb₃Ge₂O₇ and Pb₃GeO₅ were found to exist. The crystal structure of Pb₃Ge₂O₇ had a hexagonal symmetry witha=10.16 Å andc=19.37 Å, and Pb₃GeO₅ was classified into orthorhombic system witha=4.85 Å,b=15.52 Å and c=11.77 Å.     

Phase relations and activities in the Co-Ni-O system at 1373 K

The tie-lines delineating equilibria between CoO-NiO and Co-Ni solid solutions in the ternary Co-Ni-O system at 1373 K have been determined by electron microprobe andedax point count analysis of the oxide phase equilibrated with the alloy. The oxygen potentials corresponding to the tie-line compositions have been measured using a solid oxide galvanic cell with calcia-stabilized zirconia electrolyte and Ni + NiO reference electrode. Activities in the metallic and oxide solid solution have been derived using a new Gibbs-Duhem integration technique. Both phases exhibit small positive deviations from ideality; the values ofG ^E/X ₁ X ₂ are 2640 J mol⁻¹ for the metallic phase and 2870 J mol⁻¹ for the oxide solid solution.     

Phase relations in the CaMnO system

The use of solid solution precursors is introduced as an effective low temperature synthesis technique which facilitates solid state reaction in selected mixed metal oxide systems. This synthesis technique has been used to study phase relations in the manganese-rich portion of the CaMnO system at temperatures below 1000°C, and has resulted in the assemblage of a new isobaric (P_O2 = 1.0 atm), subsolidus phase diagram. This diagram contains several low temperature phases having the following compositions: Ca₂Mn₃O₈, CaMn₃O₆, CaMn₄O₈ and CaMn₇O₁₂. The experimental results of this study along with literature data are used to present a proposed isobaric (P_O2 = 0.2 atm) phase diagram for the entire CaMnO system.     

Phase relations in the CuFeSe system at 300°C

Phase equilibria in the CuFeSe system and the stability field of the intermediate solid solution (“Se-iss”) in the system have been investigated at 300°C by means of silica tube techniques in combination with microscopic, X-ray, electron microprobe and differential thermal analysis methods. In the Se-rich region of the system, the (Cu,Fe)Se_2?X solid solution coexists stably with Cu_2?XSe, CuSe, CuSe₂, FeSe₂ and Se-iss while, in the central portion, this last phase coexists with (Cu,Fe)Se_2?X, FeSe₂, γ-Fe_1?XSe, δ-Fe_1?XSe and Cu_2?XSe. The stability fields of Se-iss at 300°C and 500°C have been divided into quenching zones based on the presence of one or the other of two optically and compositionally different types of Se-iss. It was also determined that β-FeSe dissolves, at 300°C, up to 11.5 at .% of Cu. The stability of the Cu_2?XSe Fe tie-line in the metal-rich region of the system was confirmed.     

Phase relations and magnetic properties of alloys in the Co<Subscript>3</Subscript>Sn<Subscript>2</Subscript>-Bi system

The phase diagram of the Co₃Sn₂-Bi system has been constructed using physicochemical characterization techniques. The system is pseudobinary, with a limited series of Co₃Sn₂-based solid solutions (～7 at % Bi) and a liquid-liquid miscibility gap in the composition range ～14–88 at % Bi. A Co₃Sn₂-based solid solution containing about 7 at % Bi has been shown to possess spontaneous magnetization in the temperature range 80–400 K. Its Curie temperature exceeds 400 K.     

Phase relations in the PbF2-BaF2-ZrF4 system

We have investigated phase equilibria between PbZrF₆ and the barium fluorozirconates Ba₂ZrF₈, Ba₃Zr₂F₁₄, BaZrF₆, and BaZr₂F₁₀. The PbZrF₆-Ba₂ZrF₈ join has been shown to be pseudobinary, with simple eutectic phase relations. It defines the PbZrF₆-ZrF₄-Ba₂ZrF₈ compatibility triangle in the PbF₂-BaF₂-ZrF₄ system. Semicrystalline samples have been obtained at ZrF₄ contents in the range 40–70 mol %.     

Phase relations in the system CaO-B2O3-SiO2

Phase relations in the lime-rich portion of the system CaO-B₂O₃-SiO₂ have been studied by microscopy, infrared spectroscopy and X-ray powder diffraction of heated mixtures and quenched charges. Extensive solid solution of B₂O₃ in Ca₂SiO₄ occurs along the Ca₂SiO₄-Ca₃B₂O₆ boundary, which has been studied in detail. It contains a ternary compound, Ca₁₁B₂Si₄O₂₂, which is stable to liquidus temperatures, melting incongruently to Ca₂SiO₄ and liquid at 1420 °C. Ca₁₁B₂Si₄O₂₂forms a eutectic with Ca₃B₂O₆ at 1400 °C and, in the ternary system, with CaO and Ca₃B₂O₆ at 1390 °C.     

Phase relations in the HgCr2Se4-CdCl2 system

The phase relations in the HgCr₂Se₄-CdCl₂ system have been investigated using differential thermal analysis and x-ray diffraction, and the primary crystallization field of the spinel phase in this system has been located: 560–750°C, 84–97 mol % CdCl₂. By optimizing growth conditions and using CdCl₂ as a flux, single crystals of Hg_1?x Cd_xCr₂Se₄ solid solutions containing up to 5 wt % Cd have been grown.     

Thermodynamic properties of alloys and phase equilibria in the In-Sn-Sb system

We report the thermodynamic properties of alloys and phase equilibria in the In-Sn-Sb system studied by emf measurements at temperatures from 600 to 830 K. Different types of exchange reactions in the electrochemical cell (?) W|In|In⁺ in electrolyte |In _x Sb _y Sn _z | W (+) are considered, and the ways of reducing their influence on the accuracy of emf measurements are analyzed. A number of T?x sections of the In-Sn-Sb phase diagram are refined.     

Phase equilibria and thermodynamic properties in the system Ni-Mo-O

Coexisting phases in the Ni-Mo-O ternary system at 1373 K have been identified by X-ray diffraction, optical microscopy and scanning electron microscopy. The samples were equilibrated in evacuated quartz capsules. Only one ternary phase, NiMoO₄, was found to exist in the system. The reversible e.m.f. values of the following solid-state galvanic cells were measured in the temperature range 900 to 1500 K: (I) Pt, Ni + NiO/(CaO) ZrO₂/NiO + MoO₂ + NiMoO₄, Pt; (II) Pt, Mo + MoO₂/(CaO) ZrO₂/O₂, Pt; and (III) Pt, Mo + MoO₂/(CaO) ZrO₂/Ni-Mo + MoO₂, Pt. The Gibbs energies of formation of NiMoO₄ and MoO₂ and activities in Ni-Mo alloys were derived from the e.m.f. data. For the reaction NiO + MoO₂ + 2(02) NiMoO₄ we obtain G _r ⁰ = -201 195 + 69.70T (±400) J mol^–1; for Mo + (02) MoO₂ we obtain G _f ⁰ = –578880 + 168.5T (+500) J mol^–1. Based on the information from phase identification studies and thermodynamic stabilities, the isothermal section and oxygen potential diagram for the Ni-Mo-O system at 1373 K have been developed.