The carbothermic reduction of protactinium pentoxide and first results on protactinium carbide

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Abstract

The reduction of Pa2O5 with carbon has been investigated in the temperature range 1000–2200°C. As a first step at about 1100°C reduction of Pa2O5 to PaO2 occurs, followed by complete reduction to PaC at higher temperatures and reduced pressures. The CO-equilibrium pressures of the reaction: PaO2 + 3C = PaC + 2CO have been determined in the temperature range of 1290–1440°C. The temperature dependence is given by: log Pco = 12,07−19940/T (with Pco in torr).

The PaC structure has been identified from X-ray powder patterns as being identical to those of the other actinide monocarbides (fcc structure, NaCl-type a0 = 5,0608 ± 0,0002 Å). At temperatures above 2000°C and with an excess of free carbon formation of a higher carbide, probably the dicarbide, PaC2 could be observed.

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    Citation Excerpt :

    The flow requires a correction due to a transition regime for temperatures higher than 1550 K (Fig. 2(b)). Though this work deals with the carbothermic reduction of protactinium oxide, some additional measurements were also performed on the U–C–O system [21]. A pelletized mixture of U3O8 and graphite was used as starting material.

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Part of Ph.D. thesis R. Lorenz, T. U. Braunschweig 1969.

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