Paper 12.6

Thermodynamics of the In-Sb System and Gaseous Phase of Antimony Determined by Vapour Pressure Measurements

Zajączkowski Andrzej , Botor Jan

Institute of Non-Ferrous Metals, Sowińskiego 5, 44-101 Gliwice, Poland

The thermodynamic properties and phase relations in the In-Sb system were assessed. The gaseous phase of this system was described with a use of a model in which Sb₃(g) particle presence was assumed. The consistent set of thermodynamic parameters was calculated using mass loss rate data obtained during the investigation by the Knudsen effusion method and data on enthalpy of mixing derived from literature. Various thermodynamic properties and the phase diagram of the In-Sb system were calculated basing on these parameters. The calculated quantities correspond very well to the presented in the literature, except for the Gibb’s free energy of formation of InSb(s) and thermodynamic data describing thermodynamic properties of Sb₃(g). In the last case, the paper provides new, not published, data. These are the standard enthalpy of antimony trimer sublimation:

,

as well as formula describing temperature dependency of Gibb’s free energy function of Sb₃(g) in the range of temperatures 730-1300 K:

.

Value of condensation coefficient on solid antimony for antimony tetramer was also assessed. It is comprised within the range of:

and is close, at least with respect to the order of magnitude, to the condensation coefficient of arsenic tetramer.