Protactinium vapor pressure

The light actinide metals (Th, Pa, and U) have extremely low vapor pressures. Their preparation via the vapor phase of the metal requires temperatures as high as 2375 K for U and 2775 K for Th and Pa. Therefore, uranium is more commonly prepared by calciothermic reduction of the tetrafluoride or dioxide (Section II,A). Thorium and protactinium metals on the gram scale can be prepared and refined by the van Arkel-De Boer process, which is described next. 

Table XIV). Gaseous ammonia reacts with both the penta- and the tetrachloride to yield a yellow solid believed to be a nitride and some evidence for the existence of a monocarbide has been observed during the reduction of protactinium tetrafluoride in a carbon crucible (125). Vapor pressure data for carbide produced by neutron irradiation... 

Protactinium see also Elements electrical resistivity, 12-39 to 40 electron configuration, 1-18 to 19 heat capacity, 4-135 history, occurrence, uses, 4-1 to 42 ionization energy, 10-203 to 205 isotopes and their properties, 11-56 to 253 magnetic susceptibility, 4-142 to 147 physical properties, 4-133 to 134 thermal properties, 12-201 to 202 vapor pressure, high temperature, 4-136 to 137... 

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