Praseodymium dhcp structure

The lanthanide metals should also be investigated to higher pressures than previously applied. It is not excluded that their 4 f electrons also participate in bonding as do the 5 f s of Bk and Cf, after the dhcp, ccp and, possibly, distorted fee phases have been reached. An indication of this possibility can be seen in the recent discovery of the a-uranium structure type in praseodymium (Pr IV) . This structure type was previously observed for cerium, but was thought to be restricted to that metal which has an exceptional position among the lanthanide elements. 

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