THERMODYNAMIC PROPERTIES AND HIGH-TEMPERATURE EVAPORATION OF GADOLINIUM SILICIDES IN VACUUM

Using the methods of mass-spectrometric and x-ray diffraction analysis to investigate their high-temperature evaporation in vacuum, it was d etermined that gadolinium silicides undergo the sequence of phase tran sformations Gd5Si3 --> Gd5Si4 --> GdSi. The enthalpies of the phase tr ansformations were calculated, as well as the enthalpies of formation of the silicides (-116.6, -521.6, and -502.5 kJ/mole for GdSi, Gd5Si4, and Gd5Si3, respectively). The results obtained are compared with dat a in the literature.