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Lattice dynamics and thermal properties of SrHfO 3 by first‐principles calculations
Author(s) -
Murata Hidenobu,
Yamamoto Tomoyuki,
Moriwake Hiroki,
Tanaka Isao
Publication year - 2009
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.200945041
Subject(s) - phonon , bulk modulus , soft modes , octahedron , condensed matter physics , bar (unit) , ground state , lattice (music) , thermal expansion , thermodynamics , chemistry , materials science , crystallography , physics , crystal structure , atomic physics , quantum mechanics , acoustics , dielectric , ferroelectricity , meteorology
First‐principles lattice dynamics calculations are systematically made on four polymorphs of SrHfO 3 . The hierarchy of the total energy at the ground state is Pm $ \bar 3 $ m > I4/mcm > Cmcm > Pnma, which agrees with the sequence of iterative transitions with temperature as reported by experiments. Three structures, Pm $ \bar 3 $ m, I4/mcm and Cmcm, are found to be dynamically unstable at the ground state. A soft mode of phonons appears in I4/mcm and Cmcm at the Γ‐point. The atomic displacements for the soft mode are analogous to those of the R 25 mode of Pm $ \bar 3 $ m, which is related to the rotation of the HfO 6 octahedron. Pnma phase shows lowest energy and it is the only dynamically stable structure among the four phases. The volume expansion coefficient, bulk modulus and heat capacity are computed within quasi‐harmonic approximations using the vibrational density of states. They are compared to experimental data. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)