Investigation of BaSO4-KPO3-Na2B4O7 Low-Melting Glass System as a Basis for Synthesis of a Glass-Solder Material

The possibility of using the compositions of BaSO4-KPO3-Na2B4O7 system as a glass-solder (frit) material was shown. A glass formation region has been established in BaSO4-KPO3-Na2B4O7 system which is located in the borate-phosphate part of the concentration triangle and occupies ~41% of the triangle area. The concentration dependences of linear thermal expansion coefficient (TCLE), the softening temperature and the glass transition temperature was determined and discussed. It is established that the glass formation region, the concentration dependences of TCLE and technological temperatures values are significantly closer to those for CaSO4-KPO3-Na2B4O7 system than for MgSO4-KPO3-Na2B4O7 system. That may point out at the similar effect barium sulphate and calcium sulphate doping in the sulphate-phosphate-borate systems.

The enthalpies of mixing of ternary liquid Ag-Ca-Ge alloys

Partial and integral enthalpies of mixing of the ternary Ag–Ca–Ge melts were determined for the first time by the high-temperature isoperibolic calorimetry at 1300–1550 K. The experiments were performed for six sections with a constant ratio of two components up to the molar fraction of the third component equal to 0.3. The enthalpies of mixing in this ternary system are exothermic values which increase in absolute value from the Ag corner of the concentration triangle towards the constituent binary Ca–Ge system. The minimum value of the integral enthalpy of mixing was obtained for Ca0.6Ge0.4 composition of the Ca–Ge binary system (about –58.00 kJ mol–1). The enthalpies of mixing of the ternary Ag–Ca–Ge melts are calculated for the whole concentration triangle by the Redlich-Kister-Muggianu method, taking into account the term of specific ternary interaction defined from our experimental data. The topology of the isoenthalpies of mixing is determined.

Defining Borders of Vitrification Region in the Li2O⋅B2O3-B2O3-Yb2O3⋅B2O3 System

ABSTRACTPhase relations along the Li2O⋅2B2O3-Yb2O3⋅B2O3 polythermal section of the Li2O –B2O3–Yb2O3 system were investigated by differential thermal analysis, x-ray diffraction, and microstructural analysis. The state phase diagram of the Li2O⋅2B2O3-Yb2O3⋅B2O3 section is an eutectic system with invariant eutectic point corresponding to ∼0.2 mole fraction of Yb2O3⋅B2O3 and 800 °C. According to physico-chemical analysis, the Li2O⋅2B2O3-Yb2O3⋅B2O3 polythermal section is quasi-binary, allowing us to partially triangulate the Li2O-B2O3-Yb2O3 system. The borders of the glass formation region were defined in the Li2O⋅2B2O3-B2O3-Yb2O3⋅B2O3 concentration triangle. The vitreous samples showed a semiconducting nature.

Omega-phase in Ti-Hf-Zr alloys produced by the hydride-cycle methodSpecial issue on Neutron Scattering in Canada.

We report the presence of large proportions of ω-phase in Ti-Hf-Zr alloys, prepared using the hydride cycle technique. We show that the ω-phase extends across the concentration triangle of Ti-Zr-Hf and report the partitioning of the three metals across the two sites in this structure from neutron and X-ray data. We examine the symmetry of the order parameter governing the β–ω phase transition and show that a two-step model for the phase transition involving site ordering followed by displacement is not likely to be correct. We suggest that an interstitial solid solution of oxygen and octahedral vacancies exists, and that the observation of any ω-phase diffraction pattern of alloys of these metals at ambient temperature and pressure should be viewed as a potential sign of the presence of oxygen in the octahedral interstitial sites.

Subsolidus area of the system CdO - V2O5 - Fe2O3

Phase diagrams in the subsolidus area of the systems FeVO4 - CdO and FeVO4 - Cd2V2O7 have been deduced using the results of XRD and DTA analyses. On the basis of these diagrams and some additional verifying research, a projection of the subsolidus area of the CdO - V2O5 - Fe2O3 system onto the plane that comprises the components’ concentration triangle has been presented. The H-type phase is the only phase formed in this system. It co-exists at equilibrium with other phases in six subsidiary subsystems.

Heterogeneous Design. Structural diagrams of ternary systems

ABSTRACTIt is proposed to supplement a phase diagram by a structural diagram, which represents the mass portions of phases, conglomerates or their elements upon the system concentration at fixed temperature. Methods of structural diagrams and concentration maps construction are considered. Concentration map is a projection of structural diagram. It marks a concentration triangle by the lines of constant mass portions of a phase or its elements.