Activity Determination in the Alumina-Dysprosia System by Knudsen Effusion Mass Spectrometry

摘要

The vaporization of Al-Dy-O mixtures has been investigated by the Knudsen effusion mass spectrometry technique. The saturated vapor has been found to consist of the atoms Al, O and the molecules AlO, Al_2O, DyO. At the initial stage the vaporization of Dy_2O_3 and Al_2O_3-Dy_2O_3 mixtures was found to be incongruent and accompanied by some loss of oxygen. An attainment of congruently vaporizing composition and equilibrium state takes quite a long time. The activities of binary oxides have been measured at T = 2130 K. The Gibbs energies and enthalpies have been derived for formation of the compounds Dy_4Al_2O_9, DyAlO_3 and Dy_3Al_5O_(12) from sesquioxides.