Protactinium alloys

The preparation of the metal was first reported by von Grosse (80) who obtained it by bombarding protactinium pentoxide with 35 keV electrons in a high vacuum and by decomposing the pentachloride on a hot wire. No properties were reported for these products and more recently the pure metal has been obtained by reduction of protactinium tetrafluoride with lithium (73) or barium (65,125) vapor at 1300°-1400°C using the double crucible technique and on a larger scale by reduction with barium (106) or 10% magnesium in zinc alloy (107). 

In the transthorium elements (with Z above 90) there was around 1955 a controversy 16 17) whether some 6 d electrons might occur, rather than a partly filled 5 f shell in agreement with Eqs. (4) and (5). The situation seems quite complicated in alloys of protactinium, uranium and neptunium with other metals, whereas plutonium may choose between 5 f4 Pu[IV] and 5 fs Pu[III] in the individual alloys or modifications of the element. On the other hand, americium and curium seem al-... 

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