New Electronic Interactions in Rare-Earth Metals at High Pressure

Equation-of-state data have been obtained from shock-wave experiments on Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Yb, and Hf. It is deduced that only Ce exhibits phenomena that may be related to a 4f→5d electronic phase transition. An abrupt decrease in compressibility at at high pressure is taken to be evidence of the onset of interaction between closed electron shells in metals. This work is the first identification of the closed-shell electronic interactions in metals in a high-pressure experiment.