STRUCTURAL SYSTEMATICS OF 4F AND 5F ELEMENTS UNDER PRESSURE

The present knowledge on the structural systematics of the 4f and 5f e lements is reviewed with emphasis on recent new results concerning the structures of the high-pressure phases Sm-V and Nd-IV and the distort ed fee structure typical of all the ''regular'' 4f and heavier 5f elem ents at intermediate pressures. Relationships between crystal structur es and electronic configurations are discussed also from the point of view of being able to make predictions for new high-pressure phases.