Phase diagram and thermodynamic properties of compounds of the AgI–TlI–I system

The AgI–TlI–I system was investigated by a combination of DTA and XRD methods and EMF measurements with the Ag4RbI5 solid electrolyte. A series of polythermal sections and the projection of the liquidus surface were constructed. The fields of the primary crystallization and the types and coordinates of non- and monovariant equilibriums were determined. As a result, the self-consistent phase diagram of the AgI–TlI–I was drawn. The partial molar functions (ΔG¯, ΔH¯, ΔS¯) of silver iodide and silver in the alloys as well as the standard thermodynamic functions of formation and the standard entropies of AgTl3I5, AgTl2I3, and AgTlI2 were calculated from the EMF measurements.

► The self-consistent phase diagram of the AgI–TlI–I system is constructed. ► Wide immiscibility field within the border system AgI–I2 which occupies slightly more than 75% of the ternary system and covers primary crystallization areas of AgTlI2, AgTl2I3 and AgTl3I5. ► Standard thermodynamic functions of formation and standard entropies of AgTlI2, AgTl2I3 and AgTl3I5 are calculated from the EMF measurements data.