Protactinium monocarbide

The first reliable information on the protactinium-carbon system was reported by Lorenz and ScherfF who prepared the monocarbide, PaC, by carbothermic reduction of Pa20s. The dioxide, Pa02, is first obtained at approximately 1100°C and is then converted to PaC above 1900°C. In the presence of excess carbon there is some evidence for the formation of the tetragonal dicarbide. Protactinium monocarbide is isostructural with other actinide monocarbides possessing the fee NaCl-type of structure with Oo = 5.0608 A. In contrast to ThC and UC, however, it is stable in the atmosphere and is relatively inert toward acid solutions. By measuring the CO equilibrium pressures for the reaction,... 

Protactinium monocarbide was prepared by carbothermic reduction of the pent-oxide and treated with iodine (400 C), bromine (350 C), and thionyl chloride (200°C) in evacuated sealed tubes to give the appropriate pentahalide. The tetraiodide was obtained by interaction of the monocarbide with either protactinum pentaiodide (600 °C) or mercury(ii) iodide (500 °C) in vacuo. 

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... 

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See also in sourсe #XX -- [ ]

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