• Mchardy, J. D.
• Storm, C. V.
• Mcmahon, M. I.
• Plekhanov, E.
• Bonini, Nicola
• Macleod, S. G.
• Pace, E. J.
• Stevenson, M. G.
• Finnegan, S. E.
• Weber, Cedric

Abstract

<p>Angle-dispersive x-ray powder diffraction experiments have been performed on praseodymium metal to a pressure of 205 GPa. Between 20 and 165 GPa only the oC4 (α-uranium) phase is observed, in agreement with previous studies. At 171(5) GPa we find a transition to a tetragonal tI2 phase which is isostructural with the high-pressure post-oC4 phase seen in the neighboring lanthanide cerium above 12 GPa, and with the high-pressure phase of the actinide thorium seen above 100 GPa. Electronic structure calculations determine the oC4→tI2 transition to occur at 130 GPa at 0 K, but find another phase, with the hP1 (simple hexagonal) structure, to have a lower enthalpy than both the oC4 and tI2 structures above 20 GPa at 0 K.</p>

Topics

• impedance spectroscopy
• phase
• experiment
• Cerium
• Uranium
• Praseodymium
• Thorium