Как выбрать гостиницу для кошек
14 декабря, 2021
Сегодня каждый, кто собирается в отпуск и не знает, с кем оставить своего котика или кошку, может во[...]
Metallic Protactinium
Earlier laboratory processes used to prepare metallic protactinium include vacuum decomposition of the oxide by 35-keV electrons [G6] and thermal decomposition of the pentahalides [G2]. More recently, protactinium has been prepared by reducing the tetrafluoride by barium vapor [C5, S3, Zl], by calcium at 1250°C [М2] and by zinc-magnesium. The purest protactinium has been prepared by reduction in a barium-fluoride crucible at 1300°C [L2].
The two known crystalline phases of the metal, up to its melting point of 1575°C, are shown in Table 9.10 [K2].