Dynamical behavior of the phase transition of epitaxial BaTiO_3 from atomistic simulations

M. SEPLIARSKY; S. TINTE

PHYSICA B - CONDENSED MATTER

ELSEVIER SCIENCE BV

Año: 2009 p. 2730 - 2732

0921-4526

Using an atomistic shell model we study the temperature dependence of the ferroelectric properties of BaTiO$_3$ under biaxial compressive strain applicable to growth on perovskites substrate. Molecular dynamics simulations show a ``$r ightarrow c ightarrow p$´´ sequence of phase transitions when temperature is increased, and the absence of an ``$ac$ phase´´. The first-order paraelectric to ferroelectric phase transition presents in bulk changes to a second-order one as a consequence of the in-plane constraint imposed by the mechanical boundary conditions. From the tetragonal ferroelectric $c$ phase, the transition takes place in a finite range of temperature where the lattice parameter normal to the plane keeps approximately constant until T$_c$ is reached. Analysis of the local polarization behavior reveals an order-disorder dynamics as the dominant mechanism of the transition.