Condensed Matter, abstract
cond-mat/0306205

From: David Vanderbilt <dhv@physics.rutgers.edu>
Date: Mon, 9 Jun 2003 01:43:22 GMT   (36kb)

Anomalous enhancement of tetragonality in PbTiO3 induced by negative pressure

Authors: Silvia Tinte, Karin M. Rabe, David Vanderbilt (Department of Physics and Astronomy, Rutgers University)
Comments: 9 pages, with 9 postscript figures embedded. Uses REVTEX and epsf macros. Also available at this http URL
Subj-class: Materials Science
Using a first-principles approach based on density-functional theory, we find that a large tetragonal strain can be induced in PbTiO3 by application of a negative hydrostatic pressure. The structural parameters and the dielectric and dynamical properties are found to change abruptly near a crossover pressure, displaying a ``kinky'' behavior suggestive of proximity to a phase transition. Analogous calculations for BaTiO3 show that the same effect is also present there, but at much higher negative pressure. We investigate this unexpected behavior of PbTiO3 and discuss an interpretation involving a phenomenological description in terms of a reduced set of relevant degrees of freedom.

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