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A general and Eu specific perspective on lattice dynamics in pyrochlore and defect fluorite (Eu 1 − x Nd x ) 2 Zr 2 O 7
Author(s) -
Klobes Benedikt,
Finkeldei Sarah,
Brandt Felix,
Bosbach Dirk,
Bessas Dimitrios,
Embs JanPeter,
Hermann Raphaël P.
Publication year - 2015
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201552076
Subject(s) - pyrochlore , fluorite , inelastic neutron scattering , condensed matter physics , inelastic scattering , phonon , scattering , neutron scattering , materials science , neutron , chemistry , physics , nuclear physics , optics , metallurgy , phase (matter) , organic chemistry
Lattice dynamics in pyrochlore and defect fluorite type (Eu1 − x Ndx )2 Zr2 O7 were investigated using nuclear inelastic scattering by the151 Eu Mössbauer resonance for x = 0, 0.5, and 0.75 and using inelastic neutron scattering for x = 1. On the basis of the generalized density of phonon states obtained by inelastic neutron scattering, the vibrational entropy of the disordered defect fluorite Nd2 Zr2 O7 is found to be 12(3)% smaller than the one of the ordered pyrochlore counterpart. Accordingly, the loss of specific Zr–O coordination in the defect fluorite structure leads to a strong broadening of phonon modes. The Eu sublattice in both structure types was further characterized by thermodynamic quantities calculated using the Eu partial density of phonon states. The Eu framework is shown to be significantly softer than the other sublattices.