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      Permanent link:
      https://www.ias.ac.in/article/fulltext/boms/045/0186

    • Keywords

       

      High pressure; lanthanides; crystal structure; actinides.

    • Abstract

       

      The pressure-induced structural phase transitions in the lanthanide elements provide insight into changes in their electronic structures at high densities. After a series of transitions via close-packed structures, the regular trivalent lanthanides (La to Lu, excluding Ce, Eu and Yb) undergo first-order transitions to so-called collapsed phases, the structures of which have long been reported as monoclinic. However, the diffraction data from these phases are not wellfitted by this monoclinic structure, and the patterns from Nd and Sm are distinctly different to those from the higher-Z lanthanides (Gd${\rightarrow}$). Here we present results from recent diffraction studies on Tb, Gd, Sm, Nd and Y to above 300 GPa,which reveal that there are two different collapsed structures, neither of which is monoclinic. High-precision equation of state studies of the same elements reveal distinct changes in compressibility once the collapsed phases are obtained. Wealso show that these new structures are strikingly similar to those observed in the higher-Z actinides at high pressure, greatly strengthening the structural systematics of the 4f and 5f elements.

    • Author Affiliations

       

      MALCOLM I MCMAHON1 SARAH E FINNEGAN1 EDWARD J PACE1 CHRISTIAN V STORM1 MICHAEL G STEVENSON1 SIMON G MACLEOD2 EVGENY PLEKHANOV3 NICOLA BONINI3 CEDRIC WEBER3

      1. SUPA, School of Physics and Astronomy, and Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh EH9 3FD, UK
      2. AWE Aldermaston, Reading RG7 4PR, UK
      3. Theory and Simulation of Condensed Matter, Department of Physics, King’s College London, The Strand, London WC2R 2LS, UK

    • Dates

       
      Published
      22 September 2022
      Manuscript received
      29 April 2022
      Accepted
      8 June 2022
      Final version published online
      22 September 2022

  • Bulletin of Materials Science | News

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