Phase transformations in hydrides of rare‐earth metals under pressure

Abstract

AbstractAn analysis of the specific volume dependences on atomic number is carried out for rare earth dihydrides and trihydrides. It is shown that under high pressures the following phase transformations are possible in these compounds: a) structural phase transitions h.c.p.→f.c.c., the ion valency being unchanged, b) phase transitions accompanied by a change of metal ion valency. The dependences of volume versus pressure to 24 kbar and resistivity versus pressure to 20 kbar are measured for NdH2.82 at 20 °C. A reversible resistivity anomaly and an abrupt change of the volume by 1.6% are detected under high pressures. These anomalies are explained to be due to the phase transformation h.c.p.⇄f.c.c.