Polonium vapor pressure over polonides of scandium, dysprosium and holmium

The Knudsen effusion method, using a water-cooled sealed evacuated ampul, in which the effusion cell with the sample was heated with high-frequency currents, was used to determine the vapor pressure of polonium above scandium, dysprosium, and holmium polonides. The vapor pressure of polonium above scandium polonide at 1200 and 12500C was (6.4+-1.3).10-2 and (1.0+-0.2).10-1 torr, respectively. The vapor pressure of polonium above dysprosium polonide at 1300, 1400, and 16000C was correspondingly equal to (3.8+-0.8).10-3; (1.2+-0.3).10-2; (1.2+-0.3).10-1 torr. The vapor pressure of polonium above holmium polonide at 1300 and 13500C was correspondingly equal to (0.5+-1.9).10-4; (3.6+-0.8).10-3 torr. The simultaneous evaporation of the rare-earth elements and polonium was established. The general principles of the vapor pressure of polonium above polonides of the rare-earth metals were analyzed