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Inelastic Neutron Scattering and Density Functional Theory–Molecular Dynamics Study of Si Dynamics in Ti 3 SiC 2
Author(s) -
Kearley Gordon J.,
Gray Veronica,
Riley Daniel P.,
Kirstein Oliver,
Kutteh Ramzi,
Kisi Erich H.
Publication year - 2014
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.12725
Subject(s) - anharmonicity , inelastic neutron scattering , molecular dynamics , density functional theory , inelastic scattering , neutron , scattering , neutron scattering , atomic physics , molecular physics , materials science , physics , condensed matter physics , chemistry , computational chemistry , nuclear physics , optics
Observed differences between measured and calculated elastic constants for Ti 3 SiC 2 are investigated using Density Functional Theory and Inelastic Neutron Scattering. The agreement between the calculated lattice dynamics and the dynamics measured by inelastic neutron scattering is considered good except at energies below ~20 meV where discrepancies suggest anharmonic potentials. This suggestion is confirmed by Density Functional Theory—Molecular Dynamics simulation which shows multiple site occupancy of the Si atoms within the basal plane at finite temperature and produces a calculated inelastic spectrum in better agreement with the measured spectrum in the low‐energy region. The highly anharmonic potential energy surface of the Si atoms offers an explanation for the failure of elastic constants, calculated based on the harmonic approximation, to agree with initial experimental measurements.