Plutonium dioxide oxide reduction

Semiempirical calculations of free energies and enthalpies of hydration derived from an electrostatic model of ions with a noble gas structure have been applied to the ter-valent actinide ions. A primary hydration number for the actinides was determined by correlating the experimental enthalpy data for plutonium(iii) with the model. The thermodynamic data for actinide metals and their oxides from thorium to curium has been assessed. The thermodynamic data for the substoicheiometric dioxides at high temperatures has been used to consider the relative stabilities of valence states lower than four and subsequently examine the stability requirements for the sesquioxides and monoxides. Sequential thermodynamic trends in the gaseous metals, monoxides, and dioxides were examined and compared with those of the lanthanides. A study of the rates of actinide oxidation-reduction reactions showed that, contrary to previous reports, the Marcus equation ... 

Both plutonium trifluoride and tetrafluoride can be prepared by hydro-fluorination of plutonium dioxide. The oxidation-reduction relations of plutonium (III) and (IV) are such that it is readily possible to specify which of the fluorides shall be the product. If the reaction is carried out under reducing conditions, then the product is PuF3, and under oxidizing conditions, PuF4 ... 

Plutonium metal is obtained by metallothermic reduction of plutonium dioxide (PuG ) or plutonium tetrafluoride (PuFJ in a molten salt such as CaCl with molten calcium as a re-ductant and in an argon or helium inert atmosphere to prevent oxidation using magnesia crucibles. 

Americium, californium, and einsteinium oxides have been reduced by lanthanum metal, whereas thorium has been used as the reductant metal to prepare actinium, plutonium, and curium metals from their respective oxides. Berkelimn metal could also be prepared by Th reduction of Bk02 or Bk203, but the quantity of berkelium oxide available for reduction at one time has not been large enough to produce other than thin foils by this technique. Such a form of product metal can be very difficult to handle in subsequent experimentation. The rate and yield of Am from the reduction at 1525 K of americium dioxide with lanthanum metal are given in Fig. 2. 

---