Journal
COMPUTATIONAL MATERIALS SCIENCE
Volume 124, Issue -, Pages 92-97Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.commatsci.2016.07.010
Keywords
Negative thermal. expansion; Phonon spectra; First-principles calculations; Gruneisen parameter; Vibrational mode
Categories
Funding
- National Natural Science Foundation of China [11547221, 11447155]
- Natural Science Foundation of Henan Province in china [142300410250]
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By using first-principles calculation and quasi-harmonic approximation method, we have systematically investigated the thermal expansion properties of tetragonal phase of PbTiO3, focusing on the correlation between the Al (TO) mode and negative thermal expansion (NTE). It is found that volume of the unit cell shows positive thermal expansion in a axis direction, and NTE in c axis direction from 0 K to 900 K. It is also found that the A1(TO) mode is softening when the volume shrinks by the phonon calculation. Calculating of Gruneisen parameters show that the A1(TO) mode makes a main contribution to the NTE, and this vibrational mode is the Pb, Ti and O atoms' relative motion in c axis direction, which lead to a shrink of the unit cell in this direction. Our calculations clarify the correlation between the phonon mode and NTE of PbTiO3 in c axis direction at the atomic level, and provide an important theoretical basis for further understanding of the mechanism of the NTE. (C) 2016 Elsevier B.V. All rights reserved.
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