Abstract :
The vaporization of DyI3(s) was investigated in the temperature range between 833 and 1053 K by the use of Knudsen effusion mass spectrometry. The ions DyI2+, DyI3+, Dy2I4+, Dy2I5+, Dy3I7+, and Dy3I8+ were detected in the mass spectrum of the equilibrium vapor. The gaseous species DyI3, (DyI3)2, and (DyI3)3 were identified and their partial pressures determined. Enthalpies and entropies of sublimation resulted according to the second- and third-law methods. The following sublimation enthalpies at 298 K were determined for the gaseous species given in brackets: 274.8±8.2 kJ mol−1 [DyI3], 356.0±11.3 kJ mol−1 [(DyI3)2], and 436.6±14.6 kJ mol−1 [(DyI3)3]. The enthalpy changes of the dissociation reactions (DyI3)2=2 DyI3 and (DyI3)3=3 DyI3 were obtained as ΔdH°(298)=193.3±5.6 and 390.3±13.0 kJ mol−1, respectively.
