Electrical measurements on praseodymium metal to 179 GPa using designer diamond anvils

The electrical and magnetic properties of light rare-earth metals and trans-plutonium actinide metals are of interest to study the f-shell delocalization phenomenon under high compressions. Using designer diamond anvil technology, sensitive electrical four-probe measurements were performed on light rare-earth metal praseodymium to pressures of 179 GPa at room temperature. We document an average drop in resistivity of 53% at a pressure of 20 GPa in a series of high-pressure experiments. This large drop in resistivity provides the strongest experimental evidence yet for the view that the 20 GPa phase transition is indeed associated with f-electron delocalization. Our results show that the precise electrical measurements are ideally suited for f-delocalization studies, especially where structural data do not provide clear evidence of this transition.