Vapor Pressures and Sublimation Enthalpies of Gadolinium Trichloride, Tribromide, and Triiodide and Terbium Trichloride, Tribromide, and Triiodide

Abstract

The equilibrium vapor pressures over GdCl3, GdBr3, α-GdI3, TbCl3, TbBr3, and α-TbI3 were measured by the torsion-effusion method. The obtained data are well represented in the covered temperature ranges by the following selected equations: Considering the vapor consists only of the monomeric form, by the second- and third-law treatment of the experimental data, the following standard sublimation enthalpies of the compounds were derived: ΔsubH°(298 K) = (311 ± 4, 292 ± 2, 279 ± 2, 296 ± 4, 288 ± 4, and 279 ± 2) kJ·mol-1 for GdCl3, GdBr3, α-GdI3, TbCl3, TbBr3, and α-TbI3, respectively.