ferroelectrics

In this letter we obtain the finite-temperature structure

of 180^o domain walls in PbTiO_3 using a quasi-harmonic

lattice dynamics approach. We obtain the temperature dependence of

the atomic structure of domain walls from 0 K up to room

temperature. We also show that both Pb-centered and Ti-centered

180^o domain walls are thicker at room temperature; domain

wall thickness at T=300 K is about three times larger than that of

T=0 K. Our calculations show that Ti-centered domain walls have a

The electric-field-induced phase transition was investigated under mechanical confinements in bulk samples of an antiferroelectric perovskite oxide at room temperature. Profound impacts of mechanical confinements on the phase transition are observed due to the interplay of ferroelasticity and the volume expansion at the transition. The uniaxial compressive prestress delays while the radial compressive prestress suppresses it. The difference is rationalized with a phenomenological model of the phase transition accounting for the mechanical confinement.

In this paper, we study the effect of normal and shear strains and

oxygen vacancies on the structure of 180^o ferroelectric

domain walls in PbTiO_3.

  The difference to the common model used is the f,g terms. The 3D FEM formulation has been derived and a new fortran program is written. The derivative matrix is symmetric. But the calculation result does not converge. I have tried every means to get a converging result. But it doesn't work, the residual norm always increases.